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Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects
1978
Shell-less opisthobranchs of Virginia and Maryland
Rosalie M. Vogel College of William and Mary - Virginia Institute of Marine Science
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Recommended Citation Vogel, Rosalie M., "Shell-less opisthobranchs of Virginia and Maryland" (1978). Dissertations, Theses, and Masters Projects. Paper 1539616894. https://dx.doi.org/doi:10.25773/v5-6gnb-fq17
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University Microfilms International 300 Woin Zeeb Head Ann Arbor. MichiQar 4Q106 USA SI Johe's Road, Tylers Green High Wycombe. Bucks. England HPiO 8 hR VOaCL, fiO|ALlE HARIE flHCiL»LES5 0PISTH06R*NCHS OF VlflGINU ANO MARYLAND,
TH{ qOLLCGE OF HILL1AH *N& M*RY IN VIRGINIA t PH,D,# 19TB SHELL-LESS OPISTHOBRANCHS
OP
VIRGINIA AND MARYLAND
A Dissertation
Presented to
The Faculty of the School of Marine Science
The College of Uliliam and Mary In Virginia
In Partial Fulfillment
Of the Requirements for the Degree of
Doctor of Philosophy
by
Rosalie M. Vogel
1977 APPROVAL SHEET
This dissertation is submitted in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
r 1 ? f l l i a ; t Rosalie Marie Vogel A
Approved, Octoher 1977
Marvin L, Wass, Ph.D., Chairman
/- ) ' / ) <'M (£ ) ( J a ^ D . ^tyrews, Ph.D.
Donald F. Boesch, Ph.D.
f ( CL* Michael Castagna, M.S./}
i i TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ...... v
LIST OF TABLES...... v ii i
LIST OF FIGURES...... x
LIST OF PLATES...... x ii
ABSTRACT...... xlv
INTRODUCTION...... 2
METHODS AND MATERIALS...... B
RESULTS...... 15
Introduction , 15
Taxonomic Account ...... 29
Key to Adults...... 31
Key to Egg Manses ...... 36
Descriptions of Species...... 39
Aplyala wlllcoxl...... 39
Phyllaplysia engeli...... 39
Elyaia chlorotjca , 41
Elysia cstulus...... 43
Henna ea c ru c la ta ...... 44
Placlda dendritica...... 46
Ercolania vanellus...... 49
Ercolanla sp ...... 50
StlHger fuscatuB ...... 51
H i Page
Alderla modesta ...... 52
Doris verrucosa * ...... , 54
PolycaTella emertoni...... , 56
Acanthodorls pilose ...... , , ...... 58
Okenla cupella...... 61
Dorldalla obacura ...... 62
Dorlopallia pharpa...... 65
Doto coronata ...... 74
Tenellla adsparsa ...... 76
Tenellla fuscata ...... 79
Ten ell la s p ...... 81
Cratena pllata...... 84
Cratena kaoruae ...... 88
Glaucus atlantlcufl...... 97
DISCUSSION...... 99
LITERATURE CITED...... 112
APPENDIX...... 121
VITA...... 159
lv ACKNOWLEDGMENTS
X am pleased to thank Dr. Marvin L. Wass, chairman of my
committee, for his long-suffering during the study. Special thanks
go to Michael Castagna for his ideas, encouragement and many discussions,
as well as to the other members of my committee; Drs. Jay B. Andrews,
Robert E. L. Black, and Donald F. Boesch for critically reading the manuscript and making suggestions for improvement.
Thanks are given to the staff of the VIMS Eastern Shore
Laboratory at Wachapreague, especially Jim Moore and Rick Hartley for
helping collect the samples and Nancy Lewis for taking care of the
animals in my absence,
1 am also pleased to acknowledge the assistance of these
people from the Chesapeake B iological Laboratory, Solomons, Maryland, who aided me in the Maryland portion of this study: Dr. Leonard F.
Schultz, Messrs. David G. Cargo and Michael J. Reber.
Thanks are given to Ms. Peggy Peoples, Mrs. Debbie Kennedy and Mrs, Alice J. Llppson for the art work and Messrs. William Jenkins and Kenneth Thornberry for the photographs. The VIMS library staff was helpful in locating certain literature and Ms, Susan Barrick
reviewed the lite ra tu re c ita tio n s. Mrs. Linda Jenkins and Mrs, Mary
Crull typed the manuscript.
Thanks are also given to Dr. Eveline Marcus of Sao Paulo,
Brazil, for some of the early identifications and instructions on opisthabranchs, and to the Division of Invertebrates, Mollugks,
Smithsonian Institution, for the use of their library and collection.
Lastly, thanks to all my friends and co-workers who have given me encouragement and assistance during these studies, especially
Jim Cumbee.
The funds for the Maryland studies were provided in part by the National Marine Fisheries Service of the Department of Commerce and the State of Maryland, Fish and Wildlife Administration, Contract no, 14-17-003-517 under public law no. 89-720.
Vi dedication
To my patents, Mr, and Mrs- William J* Vogel for th e ir constant support and many sacrifices in my behalf.
v ll LIST OF TABLES
Table Page
1. Characteristics of three orders of opisthobranchs...... jg
2. Characteristics of egg masses of opisthobranchs...... , .. 18
3. Development types in opisthobranchs, ...... 19
4. Opisthobranch development - Type I, ...... 20
5. Nudlbranch development - Types II and 111.,,,..,...,..,.,.,. 21
6. Collection data for opisthobranchs 23
7. Development of Dorlopsilla pharpa eggs ...... 72
8. Appearance of dorsal appendages in juvenile
Tenellia fuscata...... 82
9. Comparison of the eggs of three species of
Tenellia in the Chesapeake Bay...... 85
10. Development of Cratena kaoruae at 25°C ...... 93
11. Comparison of characters of Cratena pilata and
Cratena kaoruae ...... 95
12. Comparison of egg masses of Cratena p ila ta
and Cratena kaoruae ...... 96
13. List of opisthobranchs from Chesapeake Bay
and V irginia's Eastern Shore ...... 103
14. Months of collection at stations on Eastern Shore
(bay- and seaside) May 1974 to November 1975 ...... ,106
v ii l Table Page
15. Seasonality of some opisthobranchs in Chesapeake Bay
and Virginia's Eastern Shore ......
16. Seasonality of nudibranchs in Chesapeake Bay
and V irginia's Eastern Shore ...... 1^8
l x LIST OP FIGURES
Figure Page
1. Chesapeake Bay with c o llectio n sta tio n s . * ...... 9
2. Eastern Shore of Virginia with collection stations. . . 10
3. Wachapreagtie area of E astern Shore with collection stations ...... 11
4. Generic characteristics of animals studied...... 28
5. The relationship of size to age in juvenile Dariopa il i a pharpa...... 71
6. The relationship of Cratena kaoruae size to number o f cerate...... 89
7. Collection sites of Aplvsia wlllcoxi. Fhyllaplysia engeli and Glaucua a tla n tic u s In V irginia and Maryland ...... 123
8. Collection sites of Elysia chlorotlca and Elysia catulus In Virginia and Maryland...... 124
9. Collection s ite s of Hermaea cruciata and Flacida dendrltica in Virginia and Maryland ...... 125
10. Collection sites of Ercolanla vanellus. Stiliger fuscatus. Alderia modesta and Ercolania sp. in Chesapeake Bay...... , . 126
11. Collection sites of Folycerella etaertoni, Acanthodoris pilosa and Doris verrucosa in Virginia and Maryland ...... 127
12. Collection site s of Da to coronet a and Okenia cupella in Virginia and Maryland...... 128
13. Collection sites of Do rid ells obscura and Dorlopsilla pharpa in Virginia and Maryland ...... 129
14. Collection sites of Tenellia adspersa, Tenellia fuscata and Tenellia sp. in Virginia and Maryland , , .130
15. Collection sites of Cratena pilata and Cratena kaoruae In Virginia and Maryland...... 131
x LIST OF FIGURES (C o n tin u ed ).
Figure Page
16. Typical surface salinity pattern in the Chesapeake Bay and tributary estuaries from Pritchard 1952...... 132
x i LIST OF PLATES
P late Page
1. Generalised dorid nudibranch ...... 133
2. Generalised eolld nudibranch ...... 134
3. Aplysia wlllcpxl and Phyllaplysia engell 135
4. Elysia chlorotlca ...... 136
5. Ercolanla sp. and Elysia catulus ...... 137
6. StlHger fuscatus and Ercolanla vanellus ...... 13B
7. Hermaea cruciata ...... 139
8. Placida dendrltlca ...... 140
9. Aider!a modesta...... 141
10. Doris yernicoaa and Acanthodorls pllosa...... 142
11. Folycerella e m e rto n l ...... 143
12. Acanthodorls pllosa and Dorldellaobscura...... 144
13. Okenia cupella ...... 145
14. Dorlopsilla pharpa and Glaucus atlanticus...... 146
15. Do to coronata...... 147
16. Tenellia adspersai Tenellia fuscats and Tenellia sp. . 148
17. Tenellia sp . 149
18. Cratena kaoruae...... 150
19. Cratena p ila ta ...... 151
20. Placida dendrltlca ...... 152
21. Dorlopgllla pharpa ...... 153
22. Dorlopsilla pharpa ...... 154
x i i LIST OF PLATES (Continued).
P l a t e Page
23. Dorlopsilla pharpa ...... 155
24. Dorlopsilla pharpa and Cllone celata ...... 156
25. Doris verrucosa. Proauberitea eplphytum and Qkenla cupella...... 157
26. T enellia ap...... > , . . . .158
x l i l ABSTRACT
Shell-less opisthobranchs of Chesapeake Bay, its tributaries and the seaside waters of Virginia’s Eastern Shore, were studied from 1968 until 1975 to determine faunal diversity, seasonality, reproduction and food habits. Laboratory culture of eggs and rearing of some larval stages was performed In all but 5 species. A total of 23 species from 18 genera of aplyslaceans, sacoglossans and oudlbrancha was identified. Of these, 8 species are reported from the study area for the first time. Tfco species, Identified only to genus, are probably new to science. The southern range of Do to coronata and Acatithodoris pllosa is extended, as is the northward range of Fhyllaplysia engeliT Keys of egg masses and adults are included to facilitate identification of the species in this area. The life cycle of Dorlopsilla pharpa, a nudibranch with direct (type 3) development is recorded for the first time. This is the first dorld nudibranch from the North American A tla n tic Coast th a t emerges from the egg mass as a ju v e n ile . Cratena p il a ta (Gould) is again separated from Cratena kaoruae Marcus by v irtu e of its shape, color, behavior and egg mass.
The opisthobranchs of the area exhibit greater affinity with cold temperate fauna than with warm temperate fauna. Of the opistho^ branchs studied, approximately 27% are amphi-Atlantic, 4% are circum- tro p ic a l and the ranaining 69% are endemic to the western A tla n tic. A larger number of species was found during the months of September and the w inter months of November, December and January.
x iv SHELL-LESS OPISTHOBRANCHS OF
VIRGINIA AND MARYLAND introduction
The opisthobranch fauna of the Chesapeake Bay region of the
eastern United States is poorly documented, even though extensive
oplathobranch studies have been done further north and south. This
study provides information on the species present and describes
seaso n ality , n atu ral h istory, feeding* spawning, development and
growth of s h e ll-le s s opisthobranchs of Chesapeake Bay and V irginia’s
Eastern Shore. It also provides keys to aid further studies In the
area.
The Opisthobranchla marine molluscs are characterized by a
reduced shell, or lack of one, in the adult stage. For respiration
they may possess either posterior gills, cerata, or a series of blood v essels. Opisthobranchs have undergone detortion, or p a rtia l detention, which produces the posterior gill position (Hyman 1967).
As with most molluscs, they are characterized by a mantle, calcareous shell {at some stage In their life cycle), muscular foot, head and tentacles. All these structures are present in varying degrees.
Opisthobranchs are hermaphroditic but cross fertilization is usually essential to egg laying. The eggs are enclosed in soft jelly masses or strings. The eggs develop into shelled veliger stages, hatch, and are planktotiic for varying periods of time. After settlement, they cast off the shell and undergo metamorphosis. Some opisthobranchs develop to the shelled veliger stage, cast off their shell, or resorb
2 3
It before hatching* while others do not develop a shell at all
(Thompson 1967}* and h atch as Juveniles*
The orders of opischobranchs studied herein are Aplysiomorpha,
Sacoglosga and Nudibranchla. The classification system follows
that of Odhner (1939) and Thompson (197G), Three of the four aub- borders of nudlbranchs are treated - Toridacea, Dendronotacea and
Aeolidacea,
Early North American papers that included opisthobranchs are those of Gould (1841)* DeKay (1843), and L. Agassiz (1850).
These papers include figures and descriptions of new species with occasional observations on eggs and food habits. These studies were mostly in shallow inshore areas. Crosier (1917-1922), published a series of papers on observations of a single species, Chromcdoris zebra. Johnson (1934)* published a "List of marine Molluscs from
Labrador to Texas." This Included the opisthobranchs and was an excellent compilation of the known animals. In the 1950's Marcus and Marcus (1955 to present) studied shallow water opisthobranchs in
North America from Texas, Florida to North Carolina* and Central and
South America south to Santos, Brazil. Their work Included descriptions, taxonomy, biogeography, habitat and occasionally information on sub stratum and egg ribbons. Opisthobranchs were included in checklists and keys of marine biota on the east coast by Miner (1950), Bookhcut
(1953), Smith (1964), Cory (1967)* Gosner (1971), Wass (1972), P o rter
(1974) and Leathern and Maurer (1976). Russell (1971) produced an index which is extremely useful in reviewing the nudibranch literature up to 1965. 4
The literature of the eastern North Atlantic indicates greater
interest in the description of opisthobranchs, possibly because of a
greater d iv e rsity of organisms there. Alder and Hancock wrote an
excellent taxonomic work with beautiful plates on British nudibranchs
in the ten-year period from 1B45 to 1855. This was supplemented by
E lio tt (1910). M iller (1961) (1962) published works on opisthobranchs
of the Isle of Man. Pruvot-Fol (1954) compiled knowledge of French
opisthobranchs. These studies are helpful because many amphi-Atlantic
opisthobranchs are encountered in my study area.
Much of the literature on sacoglossans and nudlbranchs has been
taxonomic. Most authors gave descriptions of color and appearance
of living animals as well as internal anatomy of the preserved
specimens. There has been some standardization of the characters
used for diagnosis of species but more is needed. Descriptions based
on preserved specimens are often inadequate due to loss of color and
contraction of animals. In earlier studies, life history, description
of eggs, and development of eggs and larval stages were given little
emphasis, although Alder and Hancock (1845-1855) Included observations
of egg masses and larvae of some of their species.
The larval stages of nudibranchs are planktonic and poorly understood. Thorson (1946) separated nudibranch larvae by shell
types (A, B and C) and believed they were short term plankters with-
feeding or growth activities. Thompson (1958) made a detailed study of the life history and development of a single species, Adalarja proxima (Alder and Hancock). He described two stages of free-swimming larval development; the first stage in which the animal swims upwards 5
and cannot undergo metamorphosis (obligatory state) and the second,
In which the animal swims downwards and Is able to undergo meta morphosis If the proper substratum is present (searching stage).
In a later paper (Thompson 1959), he discussed feeding In nudlbranch larvae and made an h isto lo g ic a l description of tha feeding mechanism and alimentation* Thompson (1961) reviewed the shell types given by
Thorson and sta te d th a t Thorsonfs ,FType A" was probably an immature shell and should be eliminated. He suggested shell Type 1 (“Type fl) and Type 2 (=Type C). Type 1 included spiral shells that normally form 3M to 1 whorl only, and Type 2 shells include egg-shaped, inflated shells. Hadfleld (1963) studied nudibranch larvae with particular emphasis on feeding, growth and the planktonic duration -
He found that the larvae lived longer with diatom food present and that they grew on the food. He discussed the advantages of different modes of life in the larval stages and also the interactions between larvae and adult food. Rao and Alagarswami (1960) and Rao (1961) studied Indian post-metamorphic nudibranchs in detail. Seelmen
(1967) reported on the la rv a l and p ost-larval development in the sacoglossan Aldarjq modefita. Interestingly, these larvae could spend up to A or 5 weeks in the planbtonic stage. Hamatani (1961-1967) studied the eggs and larvae of Japanese nudibranchs, and Hurst (1967) provided a standard for describing oplathobranch egg-mase types, aa
Thorson (1946) and Thompson (1961) did for shell types and Thompson
(1967) did for developmental types*
In the Chesapeake area little emphasis had been placed on the study of opisthobranchs and nudibranchs,probahly because of their lack of economic importance, u n til Cargo and Schultz (1967) observed that a species of eolld nudlbranch was a voracious predator of the acyphlstome stage of the troublesome stinging sea nettle Chrvsaora qulnqusclrrhfl (Desor). This led to investigations of this and other opisthobranchs in the Chesapeake Bay region (Vogel and Schultz 1970, Vogel 1971 and Marcus 1972a). Other reports Include observations on Eysia chlorotlca (Pfitzenmeyer 1961), Okenia cupella
(Vegel and Schultz 1970) and Hermaea cruciata (Vogel 1971) and a taxonomic account of the opisthohranchs reported in the Bay to that time (Marcus 1972a). Most of the studies on opisthobranchs of the eastern United States have been on their taxonomy and zoogeography with occasional contributions describing the eggs and larvae. The exceptions are works by Morse (1968, 1969, and 1971) on the develop ment and internal anatomy of New England species, and a study by Perron and Turner (1977) on development in Porldella obscura. The studies of shell-less opisthobranchs on the north east coast of the United
States mainly covered New England to Delaware (Gould 1870, V errill
1880-1881, Moore 1964, Franz 1968a, Loveland, e t . al. 1969, Meyer 1971,
Clark 1975 and Carlo 1977), and North Carolina to Florida (Er. ’lareus
1958, 1961; Ev. and Er. Marcus 1960, 1962, 1966, 1967a, 1967b;
Ev. Marcus 1972a, 1972b, 1972c).
My study area is the Chesapeake Bay and the waters surrounding the Eastern Shore of Virginia, in the salinity range from mesohaline to euhallne as delineated by the Venice System of classification of brackish waters (1958). It includes sand, mud and shell bottoms and depths from a few centimeters at low tide to 10 meters. Of the opisthobranchs, sacoglossans and nudibranchs are often seasonal in 7 abundance, with some appearing all year and others having short peaks of abundance and periods of absence. The shallow water opisthobranchs are found on a variety of substrata. The primary goals of this In vestigation were; 1} to describe sacogloasan and nudlbranch species of the Chesapeake area, 2) to determine seasonality of occurrence, reproduction and food habits, 3) to attempt laboratory rearing for description of life cycles and stages. A total of 15 species in
12 genera were reported previously. My paper includes 23 species from
IB genera of aplyslaceans, sacoglossans and nudlbranchs. Previous studies were done only in warm months. The phenology of oplathobranch activities requires year-long observations. Some species are found only in cold months. Comparison of regional differences In develop ment and egg masses as noted by Rasmussen (1944) were made. One species, Dorlopsilla pharpa. Is interesting because it is the first dorid nudlbranch on the Western Atlantic with modified direct develop ment (Type 3). Keys to living and preserved adults and egg masses were made. Keys by Moore (1964) in the "Woods Hole Key" and Gosner
(1971) include shell-less opisthobranchs. Several species included here are not in either key. Moore included only Woods Hole species and Gosner did not extend his keys beyond generic level. Also, the
"Woods Hole Key" used only living adults and external anatomy. 1 used external characters of both living and preserved specimens as well as some internal characters of the preserved specimens. The egg mass key is unique for the Western A tlan tic. I t is hoped that the information herein will be useful to others identifying and studying shell-less opisthobranchs an the mid-Atlantic coast. METHODS AMD MATERIALS
Sampling. Stations ware established in the inshore waters of
Chesapeake Bay and its tributaries and on the seaside of Virginia’s
E a s t e r n Shore to determine the diversity of the sacoglossans and
nudlbranchs in the study area. Bimonthly and monthly sampling was
c a rrie d out from May 1974 u n til November 1975. Data from sampling
and observations that t had previously obtained in Maryland waters of
Chesapeake Bay from 196B to 1970 were used also. Stations at
Gloucester Point* Virginia, were monitored from 1972 to 1974 (Figs.
1, 2 4 3 and Appendix 1).
Several sampling methods were used in this study: an oyster
dredge, detritus dredge, shell bags and hand collecting. Shell bags were placed in creeks on the Eastern Shore at selected sites. Dredge
samples coincided with some s h e ll bag s ta tio n s . Samples were taken
opportunistically on cruises, beachcombing and wading in shallow
creeks. Occasionally specimens were collected by other investigators.
S hell bags were 30 cm square, made of Vexar p la stic netting of
1,3, 2.0, 2.5 and 5,0 cm square mesh. The larger meshes were most effective and the smaller meshes were eventually discarded. Ten
clean oyster shells, 7,5-12,5 cm by 5.0-7.5 cm were placed in each bag and the bag was suspended from a structure such as a pier, piling,
channel marker or oyster tray. All bags were suspended about 2.5 cm above the bottom. Bricks were used to weight the bags to prevent
th e ir being moved by currents. The sh ell bags were left in the water
6 Figure 1, Chesapeake Bay with collection stations.
Figure 2, Eastern Shore of Virginia with collection stations. Chincoltogue
Saxis Island W a llo p s Island
Ononcock Creek Finney Creek
Harbor ton Pungoleogue Crsek Wachapreague H acks Neck Craddock Creek Oumby Meihodist Camp Quinby Bridge Oavis Whori
Cherrystone Creek
Fisherman s Island Figure 3. Wachapreague area of Eastern Shore w ith collection
s ta tio n s . Bradford C5, Bay
Bay for 2t and later 4, weeks. At f ir s t, two bags were used at each station but this was la te r reduced to one.
Sampling with the oyster dredge was carried out by towing the dredge behind an outboard motor boat for approximately 5 minutes.
A number of hauls were made until an average of 5 buckets of dredged material was collected at each station. Dredged sh ells were some- times examined in the field for the presence of large opisthobranchs such as Doriopsilla pharpa or Acanthodoris pllosa. Other dredged shells from the same samples were brought into the laboratory. The, detritus dredge was used only in Maryland waters of the Chesapeake
Bay. The dredge was towed behind an outboard motor boat for 5 minutes before being hauled.
Treatment of Samples. All samples were immediately placed in water from the collection station and transported back to the laboratory.
Shells were examined under water with the aid of a dissecting micro scope. Opisthobranchs and eggs were removed to finger bowls of the same salin ity water. Most of the animals were kept in standing, un aerated water. Other organisms associated with the animals were collected and identified. Temperature, salinity and other physical data were taken at each station. The material from each dredge sample, consisting mainly of Zostera, sponges, shells, mud, sand, bryozoans, hydroids, etc., was placed In shallow white plastic trays and covered with water. This was allowed to become anoxic, which induced the opisthobranchs to crawl to the sides of the tray and/or to hang by tension on the surface layer of the water, where they were collected with a spoon or pipette. At high summer temperatures, the loss of oxygen was very rapid, but at low temperatures this could require a much greater length of time. 13
Usually some of the known food organisms were placed In a bowl
with the animals. If the food was not known, a small shell, blades
of Zostera or hydroids were placed with the organism so that some
epiphytic and eplfaunal forms might be available for food.
Observations of feeding, mating, egg laying and general be
havior were made with the aid of a d issectin g microscope. The
buccal mechanism was observed while animals were crawling on the under
side of the water surface film. Observations of the larger animals
could be made without magnification* Egg masses, radulae, eggs and
larvae were observed with a compound microscope. The subjects were
placed on microscope slides with enough water to prevent drying, and
covered with a cover slip supported by bits of glass from broken cover
slips to prevent crushing of the specimen.
Photomicrographs were taken using a compound microscope with
a Polaroid camera attachment or a 35 mm camera attached to a dissect
ing microscope. The films were Polaroid P/N 55 and 105 - black and white positive-negative, and 35 mm Kodnchrome II film.
Description of the study area. The main study area can be divided Into two regions: the east side of the Eastern Shore or Sea side and the Chesapeake Bay. The Seaside has a aalinity range of
from 2B°/oo to 33°/oo, with a mean of 3D.5°/oo. The stations were set up in creeks or bays of the lagoon system between the mainland and the barrier islands (Fig. 3). This area includes low-lying salt marsh dominated by Spartina alternjflora and having tidal fluctuation of about 1.3 meters. The water is very turbid throughout the system.
Stations In the creek channels are subject to very strong currents.
Extreme low tides in February 1975 exposed almost all of the shell bags. 14
The Chesapeake Bay area on the western side of the Eastern
Shore ranged In salinity from 10°/oo to 21°/oo. The collecting sites were diverse, from marshy areas along relatively undeveloped stretches of water to busy piers In small waterfront towns. Con' dltlons were not silty on this side of the Eastern Shore except at
Saxis where nearby dredging and construction activities were in progress- The stations were located on sandy or sandy mud bottoms, or near eelgrass beds. Tides In this area fluctuate 0.6 to 1.0 meters. Stations In Maryland were In areas similar to those found on the Virginia's hayslde stations. They were located on both sides of Chesapeake Bay, Stations monitored at Gloucester Point,
Virginia, were located on piers in the York River in front of the
Virginia Institute of Marine Science laboratory. RESULTS
INTRODUCTION
The opisthobranchs collected In this study are divided Into three orders — Aplysiomorpha, Sacoglossa and Nudibranchia (Table 1)*
The aplysiomorpha possess 4 tentacles and a mantle cavity which con tains a gill plume and generally a flat, vestigial shell. They can be up to 30 or more centimeters long and weigh several kilograms.
The sacoglossans are a varied group of Individuals ranging from those that have a well developed shell In the adult stage to those that are essentially "aeolidiform”. They may have parapodia, cerata or no body projections at a ll. They are usually several m illim eters long. Nudlbranchs do not have a shell in the adult stage. There are two basic body types — those that have a solid digestive gland
"holohepatic", with gills on the dorsum (dorlds) and those that have a ramified digestive gland "cladohepatic", with cerata on the dorsum to perform the respiratory functions (eolids). The dorlds tend to be oval or round In shape and the eolids, cylindrical and slender.
Aplysiida and sacoglossans are herbivorous, while nudlbranchs are carnivorous. Generally, dorid nudlbranchs feed on sponges, bryozoans, cirripeds, ascldlsna and polychaetes. The eolids feed on cnidarians. Most species tend to be specific in their diet, occasion ally feeding on only one species of prey.
15 Table 1. Characters of three orders of opisthobranchs
Order or Suborder Characters
Aplysiomorpha respiration by gill plume; mantle cavity present, shell vestigial or absent, herbivorous, rhlnophoree and one pair of tentacles
Sacoglossa Suborder Elysiacea respiration by gill plume, cerata, parapodia or body surface; shell well developed to absent, herbivorous, rhinophores present or absent
Nudibranchia (general) shell absent in adult, carnivorous, rhinophores present
Suborder Dendronotacea rhinophorea retractile into Bheaths, cerata more or less arborescent, eolidiform , anus raid-]ateral
Suborder Doridacea g ills and rhinophores re tra c tile or contractile, anus dorsal, mantle present, doridiform, no jaws, radula broad flat ribbon, holohepatic
Suborder Aeolidacea rhinophores c o n tra c tile , cerata present, oral tentacles long and slender, anus lateral, jaws present, radular ribbon narrow, cladohepatic
16 17
Most opisthobranchs in my study area are benthic as adults.
Exceptions are Aplvaia w lllcoxl and Elysia c h lo ro tic a » which swim by undulating their mantle flaps or parapodia, and Glaucus at1ant leus. which is neustonlc. Most of the specimens in this study crawled on the under side of the surface film when they were in standing water. This facilitates collection and aids in the study of the vent ral aide. The animals were observed feeding, mating and laying eggs in th is position, and the w ater surface seemed to be used as would any other flat surface.
All opisthobranchs are hermaphrodites. Of the animals observed, several had "stereotyped" courtship behavior that was followed before each copulation. This could last from a few seconds to many minutes.
Usually there was a simultaneous transfer of sperm and both animals laid eggs after copulation. The opisthobranch will anchor one end of the egg mass and crawl away from it, depositing the eggs in a specific pattern. Sometimes the foot is used to shape the mass. There are four types of egg masses (Table 2). It is possible to identify the adult species by the characters of the egg mass. The eggs develop re la tiv e ly rapidly in the Chesapeake Bay area, with only one or two species taking longer than 10 days to hatch. There are three types of develop ment observed here as described by Thompson (1967) (Tables 3, k and
5).
The transition of opisthobranchs from the shelled to the un shelled state haa resulted in a change from passive defense to active chemical defense, 'warningr colors and evasive behavior. Most of these molluscs secrete a tnucous acid that makes them d is ta ste fu l to Table 2. Characteristics of egg masses of opisthobranchs (according to Hurst 1967) 43 4(13 44 44 f o
'O J 4 at 3 41 l J 41 OJ Ol 14-1 T3 3 •d t5 r-t d r F—1 d • T3 x y o n (fl w x X d 60 4) 4 C 3 4 CO O 0 6 J Id 4 J 4 1-1 id 1-1 1-1 id 1-1 n 4i A (fl w Uw 4U o 40 0 t 0 I C 4 m 3 O m H do CO in § Hi
t) Tl X X 43 X 4J « o 4J A13 (A G 13 bo u c 0 >1 □ IB CJ in n) o o DO n o P I * I 13 ffl P 44 □ 4 m m id O u H o □ a in o Id c ID (A M P i * N id 00 7 S j t X t I J VI VI X J I t DA X 3 01 1-1 □ 43 x 43 oo C 3 o to *J 44 t ISit d 43 d u "H OI d 0 01 3 Ql 3 3 11 CO X , x v 44a, Hi X T> X O U 43 > , , > 43 U II d) it y n S P x 3 3 x 4J fl u U d o id tu x o M rflL bo co o ^ £ o o rt 0 e at 44 3 0 >y l X fl » - r 34 •o u o “> M d p t-. on
attached at sac, or eggs mostly in small sac or center or coiled less string, some eolids, saco cylinder one end than one turn random glossans Table 3. Development types in opisthobranchs (according to Thompson 1967) <4-1 4M T3^ (a 4-t 04 I X ■fl fl 4-1 •H 4JM u a a ° ° o 01 (13 £ t I o 4-1 B 01 (J & u e o DO a a fl (+4 u c
□ o -*! -*! X £ ■c (fl m c O 11 }
X X -rtX ■—i rH iH hH Ml 41 4J 4-1 ta a 4 - 1 4-1 u xi u 4-1 4-1 o M ft « > s r XI O Pi 04 rt t r ft rt l m Cl o 5*, 0 a t r □ v x v x oft fl exo o rt ^ C J x ij 4-1 B (n 01 01 a n (S l M rl -rl X *rl X U JrH (J UH rH X X-H Jj 4-1 g: 5 3 1-1 O f f rt TO [fl ft □ PI □ ft 01 o l-i rt l r o Cl]Pi rH Ml t r 01 a lO Ol Pi rt □ B u aiX! DO 01 fl 3 3 t 3 rt m o tfl o rt u u 8 u ot tu fl rt Art i i-H 1 >> -H TO J r-i rH iH rt ■rt rH rH 4-t o oi in fl rt t r □ t r M c 00 o DC rt Pi g fl □ fl U U fl rt rH tj 4-1 ■d ft e 01 rt i-H > l TOfl rt rt-r t fli rt to 0 > rt 60 t r B rt -1 19 Table 4. Opisthobranchs with planktotropbic development (Type I) < SO 01 fl- O W cd o fl o S3 OJ a 0-1 rH W J3 n3 fl & (JOJ= !> u 01 l i- to A td>bd C oi tn (fl QJ A 5 - “5 0 l *^ . d c t ■H /1 a 0 c^j at pa <_> ___ id ,c tn o fl! 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Eolid nudlbranchs utilize the nematocystsof their cnidarian prey for defense by transferring the undischarged structures to the tips of their cerata and ejecting them when disturbed. Coloration can be exotic and flamboyant, thereby warning potential predators of their presence, or dull and cryptic, hiding the molluscs from their enemies. There are a variety of tactics used for protection, includ ing swimming, detaching from the substratum and thereby being swept away In water currents, jetting purple ink into the water for camouflage and burrowing into the prey species. Autototny of cerata and mantle edge are also used as defense measures. Some eolids are aggressive and will fight, attack and even become cannibalistic In close quarters. Collection data for the opisthobranchs studied are in Table 6. This does not include all the places each animal was found but gives representative stations with data on temperature, salinity, location, collection method and substrate. Dichotomous keys to aid in identification of adults and egg masses are also included on sub sequent pages. Figure 4 breaks down the shell-less opisthobranchs by generic characteristics. Table 6. Collection data for opisthobranchs cn rH t ■H JJ Vi u CO 41 co O d tn H rH iH O l T U 4J rH - a; r^. 4-i T-l 1-1 d P rH L) t H o u O’-. U OJ § & *rl Q 41 o o id Rt O 0J o o t O It fl u d J J T CJ X a ' o VO H iH to ■§ iH p •M CO o o & 4J o 01 cn 05 M cu 0 ■ - ■ rH rH -fl 60 60 -fl -rH Ip ■o to "H0 H ■H r—1 ■H < n pa > wa U O fl P tn fl iH P P <0 fl o •H P n60 tn on U 60 <0 p > 05 M5 Hco rH ■H x S i—l ON HU rH X w n X u e e u C E PCI p -rl X 3 id 3 cn j J - p cn id id p 1-1 TP P CO P P C (0 p OJ rt p CJ o cn 01 cd o cn 01 P ■d 01 01 QJ p 01 01 h (0 H CJ rH ld r-. o m £ jo o J4J TJ X u oKt co N Cut H 14 P p 6 u □ u 01 O- r-. 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Occohannock Creek, 15 25 Ruppia. hand 1971 Virginia Zostera 26 Table G (continued) H U H H - O I-H •H n S 5 -OO 5P m ,£ Mn .2 3 1 oM U O _ l £O E JS II 29 TAXONOMIC ACCOUNT A total of 23 species of opisthobranchs, Including 2 aplyelo- morphans, 8 sacoglossans and 13 nudlbranchs were found during study In the w aters of Chesapeake Bay and V irg in ia’s Eastern Shore: Phylum Molluaca Class Gastropoda Subclass Oplsthobranchla Order Aplysiomorpha Family Aplysiidae Aplysla wlllcoxl Hellprin 1886 Fhyllaplysia engeli Marcus 1955 Order Sacoglossa Family Elysildae Elysla chlorctica Gould 1970 Elysia catulus (Gould 1870) Family Henna e id a e Hermaea cruclata Gould 1B70 Placlda dendritica (Alder and Hancock 1855) Ercolania vanellus (Marcus 1957) Ercolania sp- Stlllg&r fuscatus (Gould 1870} Alderla modesta (Loven 184A) Order Nudlbranchia Family Dorididae Dorla verrucosa (Linnaeus 1858) 30 Family Polyceratidae Folycerella emertoni Verrill 1&81 Family Onchidorididae Acanthodoris pilosa (Abilgaard 1789) Family Goniodorididae Okenia cupella (Vogel and Schultz 1970) Fatnily Corambldae Dorldella obacura Verrill 1870 Family Dendrodorididae PoriopHilla phaTpa Marcus 1961 Family Dotoidae Goto coronata (Gmelin 1791) Family Cuthonidae Tenellia adspersa (Nordmann 1845) Tenellia fuacata (Gould 1870) Tenellia sp. Family Favorinidae Cratena pilata (Gould 1870) Cratena Kaoruae Marcus 1957 Family Glaucldae Glaucus atlanticus Forster 1777 KEY TO ADULTS LIVING AND PRESERVED 1, Dorsum lacking finger-like projections or gills. Rhinophores non retractile ...... 2 Dor Bum not as above ...... 5 2. Paired rhinophores and oral ten tacles present. Animal with groove present on right side from below rhinophore to branchial p it in mid-dorsal region. Branchial pit with one plume ...... 3 Paired rhinophores and p a r a p o d iapresent. Groove on right side and branchial pit absent ...... Body flattened dorso-ventrally, Flat, internal shell present or absent. Color green with white and/or purple spots. ,, ,, ...... Phyllaplysia engell (Figure 7, Plate 3, Page 39) Body raised in posterior two-thirds, outline like a sitting rabbit. Shell internal, flat, horny and thin, may be s lig h tly calcified . Body dark brown or green with black and yelLow markings, gill purple ...... Aplyala willcoxi (Figure 7, Plate 3, Page 39) Parapodia not meeting dorsally. Rounded head with short rhinophores resembling cat ears. Cardiac prominence very obvious. Three white bands on head; one dorsal and two lateral ...... Elysia catulus (Figure 8, Plate 6, Page 43) Parapodia overlapping dorsally; when spread, the animal resembles a heart shaped leaf. Rhinophores long and slender in life. Green with red, white, blue and light green spots ...... Elysia chlorotica (Figure B, Plate 4, Page 41) 31 32 5. Dorsal projections lacking) except rhinophores* Body round or oval* Rhinophores retractile* Mantle completely covers foot. Gill leaf lik e , located posteriorly between mantle edge and foot * . . * ...... ■ ■ ■ Doridella obscura (Figure 13, Plate 12, Page 62) Body with dorsal projections In addition to rhinophores ...... 6 6* Mantle present and extending over all, or most, of body. Gills and rhinophores retractile. Gills medio-dorsal, surrounding anus ...... * ...... * ...... 7 M antle absent or greatly reduced. Gills present or absent. Projections other than gilla present ...... 9 7. Body flat or slightly raised. Dorsum smooth or with fine papillae. Gills 4 or 5, bipinnate, located far posteriorly, Rhinophores perfoliate. Jaws and radula absent. Color orange or yellow-orange w ith brown dots on dorsum, Spicules present , ...... Doriopsillapharpa (Figure 13, P lates 14, 21, 22, 23 and 24, Page 65) Body oval with coarse papillae on dorsum 8 8. Mantle with pointed, conical-shaped papillae, Rhinophores per foliate on distal half and angled pos teriorly. Mantle does not cover foot in posterior region. Color variable...... Acanthodoris pilosa (Figure 11, Plate 10 and 12, Page 58) Mantle covered with mushroom-shaped papillae. Rhinophores perfoliate. Row of projections around pits for rhinophores and gills. Mantle completely covers foot. Two longitudinal dark stripes on dorsum obvious even when preserved...... Doris verrucosa (Figure 11, Plate 10 and 25, Page 54) 9. Dorsal contractile gills present in addition to other projections . 10 Gills lacking, but dorsal cerata present 11 33 10. Rhinophores smooth. Short conical p ro jectio n s on back. Body c y lin d ric a l. Four gilla posterior to pericardial prominence. Foot very narrow...... FoXycerella emertoni (Figure 11, P la te 11, Page 56) Rhinophores each with 3 to 5 cup-sahped leaves. Single mid-dorsal papilla just anterior to the 4 gilla. Row of papillae present on each aide along a palllal ridge. Spicules obvious on body, supporting papillae and being present on body and foot...... Okenla cupella (Figure 12, Plate 13 and 25, Page 61) 11. Rhinophores reduced to pointed folds of skin. Foot wider than body. Anal papilla median dorsal in a posterior p o sition. Cerata become la rg e r p o ste r iorly. Color olive green to yellow- brown, Eye spots noticeable, heart absent ...... Aid eria modest a {Figure 10, P la te 9, Page 52) Rhinophores prominent and well developed. Body aeolidiforra ...... 12 12. Oral tentacles lacking, rhinophores rolled. Anal papilla media-dorsal, just anterior to pericardial prominence ...... 13 Rhinophores not rolled; contractile or retractile ...... 14 13. Cerata unbranched. Branched digestive gland very noticeable over e n tire body surface. More than one row of cerata on each side of animal. Color olive green to very pale brown...... Placida dendritica (Figure 9, P lates 5, 7 and 19, Page 46) Cerata branched to form crown-shaped points at the tips. One row of cerata on each side of animal. Color transparent, with red-brown digestive gland diver ticula and shiny white spots on back and cerata. Very rare...... , ...... Hernaea cruciata (Figure 9, Plate 7, Page 44) 34 14. Rhinophores retractile into trumpet- shaped sheaths. Cerata very bulbous, w ith rows of dark p ap illae {lumps) that are red in living animals and black in preserved ones . . . , . . Dpto coronata (Figure 12, P late 14 p Page 74) Rhinophores contractile but not retractile ...... ,.,.,15 15. Rhinophores present* but lacking oral tentacles. Eye spots very noticeable due to transparent area surrounding them. Jaws absent ...... 16 May have oral tentacles or oral lobes present. Eye spots generally not surrounded by definite light patch. Jaws present ...... 18 16. Animals with black or dark red-brown coloration. Digestive gland in cerata brown or black. Color may vary from stippling to solid ...... 17 Animals with orange spots on dorsum. Dlsgestive gland In cerata bright orange, white spots on rhinophores ...... Ercolania sp. {Figure ID, Plate 4 , Page 50) 17. Cerata black with white tips. Body color v ariab le from red-brown to black. Rhinophores dark with white line on posterior side. Anal opening right of the dorso-median line, with no papilla. Stlliger fuscatus (Figure 10, Plate 5, Page 51) Cerata stippled with black. Color variable from colorless to black. No white line on rhinophores. Anal opening on a dorso- median p ap illa ...... Ercolania vanellus (Figure 10, Plate 6 , Page 49) 18. Body slender with one pair of oral tentacles. Cerata arranged in hot 3e- shoe^shaped groups on each side. Anal opening on papilla inside second horse shoe on right side..... genus Cratena ...... ,.19 Oral tentacles reduced or absent. Cerata arranged in c lu ste rs or rows on bock. Anal opening anterior to posterior hepatic lobs (acleloproctic position).... genus Tenellia ...... 20 35 19. Animal aeolidiform, Back contains three russet stripes. Rhinophores set vide. Oral tentacles attached to round, short head. Preserved specimen, rudoLa has 21 rows of 1 tooth each with 4-7 denticles on each side of central cusp Bifurcate denticles absent. Jaws yellow...... Cratena kaoruae (Figures fi and 15, Plate 18, Page 8 8) Body slender, back with carmine stripes, striking white dots outline the carmine. Stripes and outlines continue the length of the body, Rhinophores set close to gether. Oral tentacles attach to a narrow head. Preserved specimen: radula contains 19-21 rows of 1 tooth each, with 4-8 denticles around a central cusp. Bifurcate denticles prevalent. Jaws yellowish to white...... Cratena pilata (Figure 15, Plate 19, Page 04) 20. No oral tentacles. Anterior part of head rounded ...... 21 Oral lobes pointed , forms a small oral veil. Body slender. Foot almost as broad as body. Cerata arranged in clusters of 2-7 in each group and 5 or 6 groups on each side. Jaws present. No penial stylet Tenellia fuscata (Figure 14, Plate 16, Page 79) 2 1 . Body rounded, almost oval. Foot much narrower than body. Body stippled in black except around eyes and rhino phores. Anal opening Just to right □f the dorso-median line. Radula has 47 rows of 1 tooth each. Central tooth in Plate ...... Tenellia sp. (Figure 14, Plates 16, 17 and 26, Pago 81) Body slender, foot as broad as body. Slight black or brown dotted pigment on head and body. Cerata in 6 clu sters of 1-3 on each side of dorsum. Penis armed with stylet. Jaws present. Radular teeth as seen in P late ...... 1 Tenellia adspersa (Figure 14, Plate 16, Page 76) KEY TO EGG HASSES 1 . Egg mass a narrow or broad ribbon attached to substratum along length of one edge , ...... 2 Egg mass not as above , . , , ...... , ...... 4 2. Broad ribbon, free edge sim ilar to or longer than attached edge ...... 3 Narrow ribbon, free edge equal to attached edge; white or cream. Spiral on flat surfaces or coiled on upright stalks of hydroids or bryo 2oans. Many eggs, capsules may be distorted In shape. Present, late A pril-early June ...... Doto coronata (Plate 15, Page 74 ) 3. Free edge of mass longer than attached edge, giving appearance of ruffles. Color buff to white. Egg capsules frequently touch; one egg in each capsule. Present June to September ...... Doris verrucosa (Plate 1 0 , Page 54) Free edge of mass sim ilar in length to, or longer than, attached edge. Color- grey ish-white. Egg capsules rarely touch. Present, March to April ...... Acanthodoris pilosa T P T a te l2™TTage 65) 4. Egg mass an oval sac, attached to the substratum at one edge ...... 5 Egg mas 3 not as above ...... 6 5. Hass kidney-shaped, with creases in the concave side. Attached to the substratum by a mucus strand ...... Tenellia sp. (Plate 1 7 , Page 01) 36 37 Mass smooth, globular or oval. Eggs relatively large, white and one per capsule, fastened to substratum by mucus strand ...... ,. Tenellia adspersa or Tenellia fuacata {Plate 16» Page 76 and 79} 6 , Egg mass short cylinder; if coiled, less than one complete turn; attached at center or one end...... ,7 Egg mass a long cylinder attached to substratum by egg-free mucus strand ,1 1 7, Egg mass straight cylinder attached at one end, yellow, 15 tnm long. Thousands of eggs in sp iral egg strand w ithin mass. Present in May ...... Aideria modesta (Plate 9, Page 52) Egg mass curved cylinder ...... 8 8, Egg mass oval cylinder; eggs random within mass. Present October to March ...... ,. Okenla cupella (Plate 13 , Page Eggs in definite spiral within egg mass ...... 9 9, Comma-shaped mass attached to substratum by one end; eggs white. Present September to December Ercolania vanellus (Plate 6 , Page 49) Present June to October ...... Stiiiger fuscatus (Plate 6 , Page 51) Egg mass curved, rounded at one end, tapered at the other end ...... 1 0 10. Mass attached to substratum at broad, rounded end, eggs white. Present in November and December , . Polycerella entertoni (Plate 11 , Page 56) Mass attached to substratum along one side of cylinder, eggs white. Present in October Hermaea cruclata (Plate 7, Page 44) 30 11. Egg mass with conspicuous egg free mucus strand; mass generally deposited in a flat spiral, with secondary loops ,...... ,..,12 Egg mass with inconspicuous egg free mucus strand; mass generally deposited in a symmetrical spiral ...... 13 12. Egg mass in cylinder; capsules completely or partially detached. Present In summer and fall...... Cratena pilata (Plate 19, Page 84) Eggs in detached capsules within mass, 1 to 5 eggs per capsule (usual number 1 or 2). Capsule arrangement more or leas spiral. Present in spring and fall. Cratena kaoruae (Plate 18, Page 80) 13. Egg mass spiral or zig-zag; eggs white, spiral within mass ...... 14 Egg mass in tight sp iral; eggs In rows within mass, color white or yellow .15 14. Eggs 1 per capsule; mass found in January and February; poly-euhaline...... Flacida dendritica (Plate 8 , Page 46) Eggs in noticeable spiral cylinder within mass. Cylinder pinched off completely □r incompletely, separating 1 to 10 eggs into capsules; meso-euhaline. Present in May and June Elysia chlorotica (Plate 4 \ Page 41) 15. Egg mass in a clockwise sp iral (from inside out). Profile shows center of mass higher than outside} cone-shaped. Eggs yellow, 1 per capsule; poly- euhaline. Present in May, June and July...... Dorlopsilla pharpa (Plato 14, Page 65) Egg mass in counterclockwise sp iral, from outside in. Occasionally a ’pile up 1 of eggs in center. Eggs white, 1 per capsule; meso-ouhaline. Present all year on bryozaans ...... Doridella obscura (Plate 12, Page 62) 39 DESCRIPTIONS OF SPECIES Order Aplysioraorpha Family Aplysiidae Aplyala w illcoxl H eilprln 1886 (Plate 3, Figure 7) Diagnosis. Adult large, up to 30.5 cm long. Head greenish and the body olive green to brown, with black, reticulationsi gill and mantle edges light purple. Cephalic tentacles and erect rhinophores present. Eyes anterior to the rhinophores and set close to the surface. An internal shell of an amber, horny material present. Mantle flaps large and overlapping on the back when they were not being used for swimming. The animal extruded purple ink when annoyed or i r r i t a t e d . Occurrence. The single specimen observed was collected as it was swimming just under the water surface in a seaside lagoon on Virginia's Eastern Shore. This is the first record of Aplysia willcoxl from Virginia waters even though the range is from Florida (Marcus 1972c) to Cape Cod, Massachusetts (Sanford 1922). Seasonality and Food. The species was collected in October. It fed voraciously on Ulva but rejected other types of algae. M ating. Not observed. Egg Mass and Eggs. Not observed. Phyllaplysia engell Marcus 1955 (Plate 3, Figure 7) D iagnosis■ Adult up to 26 mm long. Green with small white, or pigmented pink or purple raised conical papillae on the body, and dots of white on the dorsum. Rhinophores translucent, occasionally with pinkish rings. 40 Foot and gill green. Parapodia small forms openings over palllal cavity. Oral tentacles rolled, almost like the "oral veil" seen In the genus Aplysla; rhinophores rolled. Eyes located just anterior to the base of rhinophores and set on surface. Foot rounded at anterior end and distinguished by a ridge around the widest part of the body. Mouth with pair of "lips" or oral lobes anterior to the opening (Marcus 1955). These animals possess eith er a brown cutlcular shell or none at a ll (Er, Marcus 1955, Marcus and Marcus 1957 and Ev. Marcus 1972c). The ones I collected lacked a sh e ll. Occurrence. Three specimens were collected from Eos tera beds in Cherrystone Creek, Virginia. The range is reported from Florida to Sao Paulo, Brazil (Marcus 1972c). This collection extends the range of engeli northward from Florida to the lower Chesapeake Bay. Seasonality and Food. The animals were collected in September and October. Krakauer (1971) reported P^. engeli fed on microscopic epiphytes on turtle grass (Thalassia sp.). The animals collected in this study fed on microscopic epiphytes on Zostera. Mating. Not observed. Egg Mass and Eggs. Animals collected at Cherrystone Creek were immature, which would explain why they did not spawn in the laboratory. The smallest of the animals grew to almost 6 mm during the observation. However this was probably still too small for reproduction. Remarks. The largest specimen collected was 6 mm long, the smallest was 3 mm. Marcus (1972c), reports an animal 26 mm long from Sao Paulo, Brazil, that spawned in the laboratory. The animals moved like inchuorms over the substratum, similar to the movement described for Phyllaplysia padlnae by Williams and Gosliner (1973), and occasionally 41 raised the anterior half of the body off the surface as if searching for food and/or surfaces an which to crawly The molluscs could contract almost as much as would a polyclad. The animals appeared to use cephalic tentacles as sensory structures. When disturbed, they partially unrolled cephalic tentacles and pressed them to the substratum. Order Sacoglossa Family Elysiidae Elysia chlorotica Gould 1870 (Plate 4, Figure 8) Diagnosis. Adult up to 45 mm long. Emerald green, with minute red, white, blue and occasionally light yellow green spots. Unfed animals chocolate to tan. Rhinophores folded cylinders, pointed at the tip. Foot triangular anteriorly, pointed posteriorly. Parapodia present. Body lanceolate with parapodia folded, heart-shaped or oval when expanded. Small (2.5 mm) and large (up to 45 mm) animals reveal a parapodial size range from small dorsal flaps of skin not meeting dorsally to large overlapping natatory appendages. Thompson (1976) stated that Juvenile Elysia do not possess parapodia. It is possible that the species of Ely3la he studied do not have parapodia as juveniles or that the parapodia were so small he did not see them. Occurrence. Pfiteenmeyer (1961) made the first record of II. chlorotica from the Maryland waters of Chesapeake Bay. The present study is the first report of E_, chlorotica from Virginia waters. The 41 animals observed were collected from Bloody Point to Poccmoke Sound in the Chesapeake Bay and from Wachapreague, Virginia. Further distribution is from Nova Scotia (Bailey and Bleakney 1967) to Beaufort, North Carolina (Pearse 1936). The animals associate with Kuppia. Zoatera. 42 Ulva, Vaucheria and Enteromorphs (Russell 1946). They are found in meso- to euhallne salinities and from a depth of several maters to Intertidal pools and mudflats (Russell 1946, Bailey and Bleakney 1967). Seasonality and Food. The animals occur in the study area from May to September, E. chlorotica collected front Wachapreague came through the flowing sea water system. The adults possibly feed on Enteromorpha clathrata (Roth) (Russell 1946), Ulva or Ruppia■ They can be held for several months in the laboratory without feeding if kept in the sun. Mating■ Spawning occurs in May and June. jJ. chlorotica generally mates in pairs, with the couple remaining in coitus for several hours. Small animals 8 to 11 mm mated for shorter periods of time. Only animals above 8 mm were observed mating. Egg Mass and Eggs. The eggs are white and are laid in a cylindrical mass attached to the substratum along the entire length of one aide (Type B, Hurst 1967) (Table 2). The masses may be laid in a s p ira l or randomly placed zig-zag and can be up to 110 mm in length. The largest animals laid the largest egg masses. The eggs are cncapsuled by a continuous spiral capsule running the entire length of the egg mass. The capsule is twisted at irregular intervals to form separate compart ments for the eggs. Usually there are from one to ten eggs in each compartment. The end of the egg mass may contain several compartments without eggs. Larvae. The plank-totrophic larvae hatch in 4 to 7 days at 21-25°C. They are 0.18 mm to 0.20 mm in size and have a band of black pigment around the opening of the shell. This species did not undergo meta morphosis in the laboratory. 43 Remarks. Green (1970) studied sacogloasans from the genera Elysia, Flacida, Flacobranchus and Heraaelna and found that these animals Ingest chloropiesta of their algal food. Animals In the genera ElysiaT Flacida and Flacobranchua retain the chloroplasts In a symbiotic condition while the chloroplasts In animals In the genus Hermaelna are apparently degraded. He suggests that symbiosis between animals in the order Sacoglossa and algaL chloroplasts is the rule rather than the exception (Green 1970), Marcus (1972a) reported Ji. chlorotica as being yellowish in color, but this observation was made from a photograph of an animal held In the laboratory long enough for some of its chloroplasts to be absorbed as food. Broad variation in the color of these animals Is probably due to this phenomenon. Elysia catulus (Gould 1870) (Plate 5, Figure 8) Diagnosis. Adult 3 mm long, dark to light green, three white patches on head; one lying dorsally and one lying obliquely on either side of head posterior to rolled rhinophores. Parapodia not meeting dorsally. Preserved and/or contracted animal with general outline of a cat-- hence the name catulus . Occurrence. The species ranges from Nova Scotia to Virginia, Clark (1975) s ta te s that jJ* catulus is the most abundant sacoglossan in Connecticut waters. Seasonality and Food. Six specimens were collected in the Chesapeake Bay from July to October. Marsh (1970) collected E^. catulus on Zostera marina in the York River in all seasons, with peaks of abundance in November and December. JS. catulus grazes on the cells of Zostera (Clark 1975) . 44 Mating. JL. catulus did not lay eggs or mate In the laboratory. Egg Mass and Eggs. Clark* (1975) reported E, catulus eggs In Connecticut from mid-May to early August; a fte r which all the adulta disappeared. Because of the peaks of abundance in November and December reported by Marsh (1970) * these months would be the expected spawning season for catulua in Virginia waters. Remarks. Tropical storm "Agnes" In 1972 almost completely destroyed the E_. catulus population In the Chesapeake Bay. Since that time, 1 collected only two animals from Cherrystone Creek* Chesapeake Bay. R. J. Orth (1976) has sampled Zosters extensively in the Chesapeake Bay since "Agnes" and has Found no E^. catulus. Marcus (1972a) states that since catulus is a noun, It does not need to agree In gender to the feminine Elysia. it is possible that Juvenile f£. chlorotica could be mistaken for E^. catulus because the parapodia do not meet dorsally. However, the presence of lobes on the foot of 13, chlorotica which are not present in E. catulus, and the distinct white patches on the head of E. catulus are sufficient to distinguish the two species. Family Hettnaeldae Hermaea cruclata Gould 1870 (Piste 7, Figure 9} Diagnosis. Adult aeolidiform, 10 ram, long and slender with cerata on its dorsum. Background color cream with a greenish cast. Epidermis covered with white wart-llke spots. The spots concentrate at the tips of each ceras, causing the entire end to appear white. Cerata cylindrical, with cruciform divisions of the amber-brown digestive gland diverticula at the distal end. Digestive gland divided into two lines on each side 45 of the body, joining in a ceras anterior to the tail. Foot one-half aa wide as the body, and attenuated posteriorly. Anal opening on a papilla anterior to the cardiac prominence. Penis armed with 3 hooka. Radula with 17 rows of teeth on the ribbon, 10 on the upper and 7 on the lower portion, Rhinophores rolled, containing brown pigment on the dorsal side. Eyes Just posterior to the base of the rhinophores. Occurrence. Hermaea cruclata is found in Massachusetts and Chesapeake Bay. Seasonality and Food. Specimens from the Chesapeake Bay region were collected in October and November (Marsh 1970 and Vogel 1971), The food of 11. cruclata is not known but the adults possibly feed on small algae found on Zostera. Mating - Not observed. Egg Mass and Eggs. H. cruclata laid eggs in the laboratory. The mass was comma-shaped and attached to the substratum at the center (Type C, llurst 1967) (Table 2 ). The egg capsules, each containing one white egg, were arranged In a spiral from one end of the mass to the other. The eggs averaged 0.1 mm in diameter and the egg capsules averaged 0.15 mm in diameter. Larvae. Veligers were present in the egg capsules at 3 days and hatched on the fifth day. Each veliger had a large pigment spot in its center. The shell lacked pigment. All veligers were well differentiated five days after hatching. The animala did not undergo metamorphosis in the laboratory. Remarks♦ The mating and feeding habits, as well as the later stages of development, are unknown. Marsh (1970) and Vogel (1971) collected II, cruclata from Zostera marina communities. H. cruclata is extremely 46 rare although more extensive collecting might reveal more specimens. Marsh (1970) reported two specimens from the York River and Vogel (1971) found one animal from Deal Island in the Chesapeake Bay. The original description of the animal was of a specimen collected off Naushon Island, Massachusetts (Gould 1870). All records of this species are of the four aforementioned specimens (Gould 1870, Verrlll and Smith 1874, Johnson 1934, Marsh 1970, Franz 1970, Vogel 1971, and Marcus 1972). Flacida dendrItica (Alder and Hancock 1843) (P lates 8 and 20, Figure 9) Diagnosis. Adults 7-15 mm long, Aeolldiform, with rolled rhinophores and cerata containing convoluted 'liver1 diverticula. Anal opening located on a papilla just anterior to the heart. P. dendritica white with green liver diverticula. Green color also extended Into rhinophores in a tree-like pattern, hence its name. Cerata with shiny white gland cells. Cerata uniformly located dorsally in paired rows of two. One large and one small ceras present in each row. Foot as wide as body, tapered to long posterior point. A nterior edge of food rounded. Occurrence. The distribution on the Western Atlantic is from Nova Scotia (Clark and Franz 1969) to Curacao (Marcus and Marcus 1970), Its world distribution includes the Eastern Atlantic, California, Western Canada, Japan and A ustralia (Alder and Hancock 1843, Baba 1937a, McFarland 1966, Thompson 1973 and Lambert 1976). This study provides the first record of Placlda dendritica in Virginia waters. Seasonality and Food. Eighteen dendritica were collected from algae growing on oyster trays in Swash Bay, Eastern Shore, Virginia, In late January 1974. Algal substrates were Agardhiella ep. and Bryopsls plumosa. The temperature was 7.5*C and the salinity 33 o/oo. The animals were observed feeding on the algae. Mating. Specimens were observed mating in the laboratory, but no courtship a c tiv ity was observed. They crawled to a h ead -to -tall juxtaposed position, with the reproductive openings together, and simultaneously transferred sperm. Sometimes several animals clustered but probably without mating. Egg Mass and Eggs. White eggs were la id In a clockwise spiral from the inside out 1 to 1 1/2 turns (Type B, Hurst 1967) (Table 2). The mass s iz e depended on how many times the animal had spawned (Baba and Hamatan1 1952) . There was one egg in a capsule. The egg capsule seemed to be slightly etched. The eggs were 60-65 microns in diameter and the egg capsules were 80-92 microns in width and 92-L19 microns long. Larval Development. The eggs kept at 18.5°C developed relatively slowly and reached the shelled vellger stage In 5 days and hatched at 7 days. The unhatched v e lig e rs did not contain any black pigment seen on other larval sacoglossans. The larva possessed an operculum and a ra th e r elongate s h e ll. The animal almost completely fille d the shell. Before hatching, the larval shell grew to almost fill the egg capsule. Hatching began when the egg capsule collapsed on the vellger. The vellger then forced its way backward from the egg capsule. Veligers were observed with a reduced velum after three days. Egg masses were la id at 18.5“C in the laboratory and in ambient sea w ater, 4.5 to 6BC. All the eggs seemed to be normal. The vellger contained very little yolk and fed on small algae and diatoms In th e w ater. The most strik in g phenomenon was that some of the animals a c tu a lly added up to one-third more shell. 48 Thia is rare among naked opiathobranchs, but was also noted by Green (1968) . The animal was detached from mast of the shell at that time. The velum became reduced and the foot enlarged in preparation of metamorphosis. No dendrltica completed metamorphosis and cast off its shell in the laboratory, although some completed all but the last stage of casting off the shell. Remarks■ Several F_. dendritica were left in a bowl with only the red alga Agardhiella. After a week, the animals had bleached to a light brown color. They did not eat the Agardhiella. Some Bryopsis plumosa, a green alga, was placed in the bowl after this time. The P^. dendrlt lea immediately started feeding on it. They were seen to pierce the cell wall with their radula and then suck the cell contents with a rhythmic motion. A fter the c e ll was emptied, th e animal would move to another cell and repeat the process. The green color started reappearing in the animals less than two hours after the green alga was placed in the howl. The color appeared in a pattern, with the central cerata regaining color first, then posterior, front, and finally the head legion, rhinophores and papilla. The green cell contents could be seen flowing through the digestive gland ramifications in the cerata and head. The animals remained green as long as there was food and until the food was digested. In the laboratory it was not uncommon to see an animal half green and half brown, but this was not seen in nature. A study was made of the effects of several temperatures on the development of £. dendritica eggs. A single egg mass was divided into four parts and placed in bowls having varied temperatures, and observations were recorded dally until the eggs hatched or died. 49 At 25.5°C, the eggs were apparently not able to develop normally. Development was normal and rapid u n til the animals reached the gastrula stage, after which they became abnormal—casting off cells and developing only parts of the normal vellger. The eggs at 10.0BC developed more slowly than the ones at 18.5°C but appeared to be normal. The eggs at 4.3°C (ambient sea-water) developed most slowly but hatched normally at 19 days, more than twice as long as the eggs at 1B,5°C. Some controversy has arisen as to the proper generic placement of Flacida dendritica. It was placed first in the genus Hermaea of Loven, 1844. The characters for this genus include branched "liver” diverticulae in the cerata. The genus PlacIda Trinchese, 1877, has unbranched "liver" diverticulae and branched albumen glands in the cerata. The cerata of several P. dendritica studied had knobby, unbranched "liv e r" d iv erticu lae in the cerata and branched albumen glands. This would definitely place the species dendrltica in the genus Flacida. Ercolania vanellus (Marcus 1957) (Plate 6, Figure 10) Diagnosis. Adult 3.5 mm aeolidiform with paired conical rhinophores and no oral tentacles. Cerata oval to triangular in shape, stippled with black, sometimes densely. Translucent areas present over eye spots. Anal opening located on a dorso-fliedial papilla anterior to the heart. Foot as wide as the body and rounded at the anterior end. Cerata in rows on each side of the back, 7-10 on each side. Repro ductive openings located on right side below eye and penis armed with hooks. This description agrees with that of Marcus (1957) and Marcus (1972a). 50 Occurrence. More than 50 adults were found In the Chesapeake Bay in salinities of 15 o/oo to 21 o/oo. Further distribution is Florida to Brazil (Marcus 1972a). Seasonality and Food. The animals were collected from September to December in Chesapeake Bay. They were observed grazing on micro- epiphytes on blades of Zostera. Mating. JE. vanellus mated and laid eggs in the laboratory. Court ship procedure was brief, with two animals touching and then extruding their copulatory organs. The animals aligned In Juxtaposition, head to tall, and each inserted its copulatory organ into the other. A mutual tran sfer of sperm then took place. Egg Mass and Eggs. Eggs a re laid in a comma-shaped mass attached to the substratum at one end (Type D, Hurst 1967) (Table 2), There is one egg in each capsule and 50 capsules in the mass, arranged in a strand with the sides of the capsules not touching. The egg capsules contain a granular substance that persists until the veligers are formed. Larval Development. The larvae grow from 70 microns to 130 microns and fill the entire egg capsule Just prior to hatching. The eggs are of developmental Type 1 (Thompson 1967), Table 3, No larva underwent metamorphosis in the laboratory. Ercolania sp. (Plate 5, Figure 10) Diagnosis. Adult, 3 mm, aeolidiform, with cylindrical rhinophores and no oral tentacles. Cerata arranged singly, with eight on each side of dorsumj and clear, with orange digestive-gland diverticulae in them. Black spots dorsally. Foot as wide as body. Remarks. One specimen seen alive was unlike congeners found in the Western Atlantic. The animal was placed in the genus Ercolania but it was not possible to classify it beyond the generic level. It was collected from near the mouth of the Rappahannock River in October 1971. Another specimen, presumably of the same species, was collected by Relnaldo Morales-Alamo from the Rappahannock River in October 1972. A specimen was seen preserved but was not dissected. The exact placement of this species must await collection of more specimens. S tilig e r fuscatus (Gould 1S70) (Plate 6, Figure 10) Diagnosis. Adults small (3 mm), aeolidiform, lacking oral tentacles, 1 pair of rhinophores and dorsal cerata. Cerata triangular to cylindrical in shape, arranged 5 on each side. Foot as wide as body, rounded into lobes anteriorly and tapered to a rounded t a i l posteriorly. Anal opening located dorsally to the right of the median lin e just anterior to the heart. Genital openings located on the right side below the eye. Specimens vary in color from red-brown to black, with translucent patches around the eyes and white tips on the cerata, as well as a white strip along the underside and posterior edge of the rhinophores. Rhinophores also with grooves on the underside that are only noticeable when the animal ia preserved (Thompson 1973). Occurrence. The adults were collected from the Chesapeake Bay in mid to upper mesohallne salin ities. Further distribution is from New Hampshire to Virginia (Franz 1970, Marcus 1972a, Abhott 1974, and Marsh 1970). Seasonality and Food. The animals were collected in the months ftom June to October in this study. fuscatus appeared to feed upon 52 diatoms on blades of Zostera and some species of algae. Mating. The adults had very little courtship behavior. They approached each other, aligned in juxtaposition and copulated. The animals sometimes were a short distance ap art, but usually they were touching along their hody edge. Usually each animal acted as both male and female. Copulation time lasted only a few minutes. Eggs were laid by both animals. Egg Mass and Eggs. The egg masses are comma-shaped with a d e fin ite string of egg capsules in them. There is one egg in each capsule. The mass is of Type D (Hurst 1967), Table 2. Each mass is 3 mm long with 50-100 eggs which are 100 to 180 microns in diameter. The eggs are white, with the mucus and je lly of the mass clear. la rv a l Development. Development is of Type 1 (Thompson 1967) , Table 3. The eggs developed to hatched veligers in 4-5 days. Mo animals underwent metamorphosis In the laboratory. Remarks. S tillg e r fuscatus and Ercolania yanellus can be distinguished by the white tips on the cerata of £J, fuscatus and the anal papilla of E. vanellus. jS. fuscatus also has a groove on the underside of the rhinophores when preserved. Alderla modesta (Loven 1044) (Plate 9, Figure 10) Diagnosis. Adult oval-shaped with brown or olive markings, 6 to 10 mm long and 1 mm wide at the widest part. Rhinophores vestigial and no more than pointed flaps of tissue anterior to the eyes. Foot much broader than the body, rounded anteriorly and forms a broad tip posteriorly. Eyes very noticeable and located behind the "rhinophore" flaps. Cerata located in rows on either side of the back, being 53 smallest In the anterior region and growing progressively larger posteriorly. Anal opening on a papilla located dorso-medially in the posterior one third of the animal. Reproductive openings located on the right side below "rhinophore" flaps. Heart absent, cerata perform circulatory function (Evans 1953, Marcus 1972a). Occurrence. Eighteen specimens were collected from St. John Creek, Solomons, Maryland, but the species was collected nowhere else in Chesapeake Bay, It Is found on the Western Atlantic from Nova Scotia (Bailey and Bleskney 1967) to Mew Jersey (Franz 1970a), Chesapeake Bay and Brazil (Marcus 1955, 1972a). World d istrib u tio n also includes Northern Europe to France (Pruvot-Fol 1954} and the central California coast (Hand and Steinberg 1955). Seasonality and Food. The animals were collected in a low salinity creak during the last part of May. The animals In this study were not observed feeding. They were found with Zostera and Ruppia and unidentified filamentous green algae. Clark (1975) reports A. modesta as being found on the alga Vaucheria. Mating. Little courtship procedure is observed prior to mating. The animals aligned side by side and copulated for several minutes. Egg Masses and Eggs. Egg masses were found with the adults; which mated and produced more egg masses in the laboratory. The eggs are laid in a yellowish, cylindrical jelly mass attached to the substratum at one end. The larg est egg mass observed was 20 mm long. There are 1 or 2 eggs in each egg capsule and approximately 700 in an egg mass. The capsules touch and are arranged in a spiral within the egg mass. The eggs are 100 to 150 microns in diameter and hatch in about 7 days. Larval Development. The larvae are of Type 1 (Thompson 1967), Table 3. No larvae were raised to metamorphosis in the laboratory. 54 Order Nudlbranchla Family DoridIdae Doris verrucosa (Linnaeua 175B) (Plate lOand 25, Figure 11) Diagnosis- Adult front 20 to 60 mm long* Orange-yellow or gray w ith two dark longitudinal stripes dorsally- Entire dorsal surface of the mantle covered with musltroom-ahaped papillae supported by spicules. Body shape doridiform (oval) with no large projections other than retractile brancheae and rhinophores* Arborescent hipinnate brancheae 15, located in a circle around the medlo-dorsal anus, Rhinophores perfoliate over entire length. Papillae on each side of rhinophore pit, as well as a row of papillae around branchial pit, are taxonomlcalLy important. Mantle covers entire body and foot. Calcium carbonate spicules present in mantle. Foot rounded anteriorly and narrower than body. Eye spots deep-set and not visible in the adults. Genital openings located on the right side between the mantle and foot. Radula has 6G rows of 45 to 60 teeth, jaws absent. Occurrence, j). verrucosa was collected from the Bayside of the Eastern Shore at the mouth of Cherrystone Creek. It was also collected on bricks suspended from the VIMS pier at Gloucester Foint early in June 1972, J5. verrucosa has not been seen at Gloucester Point since Tropical Storm "Agnes", although it has been found in deeper waters at Tue Marsh Light. More than 20 I), verrucosa have been found at various stations in the Chesapeake Bay where the aalinity ia polyhaline, D. verrucosa is also found in the Western Atlantic from Massachusetts (Johnson 1934, Franz 1970b) to Brazil (Marcus 1972a)t in the Eastern Atlantic from England to South Africa (Pruvot-Fol 1954) and in the Mediterranean Sea (Ibid). 55 Seasonality and Food. Thia dorid has been found in the Chesapeake Bay front June to January. I), verrucosa was found in association with several species of sponges. It has been reported feeding on Hlcroc Iona prollfera. Hallchondria bowerbankla and Haljclona canaliculata (Franz 1963). The animals burrowed into some of the sponges, such as M, prollfera, and were completely covered. The nudibranchs change color depending on the food eaten. M, prolifera produces gray animals and Jl. canallculata, yellow animals. Hating. The courtship and mating procedure was observed on several occasions. One nudlbranch approaches another from behind and touches the end of its mantle. The front animal then turns and they assume the juxtaposed, head-to-tail mating position. Early in the season, there might be a ring of 4 animals with each acting as male or female for different partners. There does not seem to be any sperm transferred in these "group" situations. Later (several days), the animals pair and actual sperm transfer takes place. In these animals, copulation takes place between animals 3-5 turn apart,with only one animal trans mitting and one receiving sperm. There is an obvious pulsating of the copulatory organ. The eggs are laid by the fertilised animal. The roles may be reversed later. Egg Hass and Eggs. The eggs are laid in a spiral arrangement. The egg mass is Type A (Hurst 1967), Table 2. This is a laterally compressed mass that stands 5 mm up from the substrate. The attached edge Is ahorter than the free one, causing the unattached edge to be wavy. The mass is buff when it is first laid, turning to white in the older masses, and can contain several thousand eggs. There is one egg per capsule and the egg capsules do not touch In the mass. The eggs contain 56 very little yolk, the average egg size is 75.11 microns in diameter, with the capsule diameter averaging 116.55 microns. Larval Development. The eggs exhibit development Type 1 (Thompson 1967) (Table 3). They reach the veliger stage 3 days after being laid and hatch at 5 days at 25°C and 20 o/oo salinity. The larvae were not raised to metamorphosis. Remarks. A specimen 40 ram long, and probably in it s second winter, was found in December. Clark (1975) states that D, verrucosa has an annual or biannual cycle. Most of the individuals found in this study were 20 mm or less long, but Abbott (1974), Pruvot-Fol (1954) and others report specimens up to 50 and 60 mm. Family Polyceratidae Polycerella entertoni Verrill 1881 (Plate 11, Figure 11) Diagnosis. Adults (3-5 mm) limaciform with non-retractile gills and rhinophores. Animal brownish-yellow, deepest in the gill region and sloped both anteriorly and posteriorly, Rhinophores solid cylinders with no projections. Pinnate gills 3, in a median-dorsal position half way between head and ta ll. Knoblike projections present along the pallial ridge on either side of the animal, extending from anterior to rhinophores to behind g ills . Foot narrow, less than 1/3 width of the body, widening anteriorly to tentacles extending beyond body. Eyes located behind the rhinophores; deep set into body. Occurrence. More than 50 emertonl were collected from the seaside of V irginia's Eastern Shore and from Chesapeake Bay. It associates with sponges, bryozoans, shells and Zostera. It is reported from the Western A tlantic from New England to Brazil (Franz and Clark 1972, 57 and Marcus 1972a); and has also been reported from the Mediterranean Sea (Schmekel 1965). Seasonality and Food. Adults of P_, emertonl were present in September- January and in April and May* As with many species, the adults collected were mature and apparently in their spawning season. Franz (1968) , and Franz and Clark (1972) reported P^. emertonl feeding on the bryozoan Bowerbankla gracilis and Marcus (1972a) , reports l>. emerton! from Miami on the bryozoan Zoobotrlon pellucidum. Mating. The courtship behavior of emertonl is relatively simple. One animal approaches the other from behind and touches the first animal with its rhinophores. The other animal turns and the two circle and align themselves ’head-to-tail’ with their genital apparatus together. While they are circling, the genitalia became enlarged and the penis of each extended. Egg Masses and Eggs. The eggs are laid in an oblong jelly bag of Type D (Hurst 1967) (Table 2), The masses are rounded at the attached end, taper to the unattached end, and range from 3 to 5 mm in length. The oval egg capsules are arranged end to end, with a small space between each capsule. The capsules, containing one egg each, are encased in a jelly string that spirals the length of the mass. Eggs range in size from 64 to 97 microns In diameter and egg capsules range from 90 to 119 microns in length. Cleavage in synchronous in the egg mass■ Larval Development. The larvae hatch in 5-9 days at 16°C, possessing uninflated s h e ila v ith few markings. Development is Type 1 (Thompson 1967), Table 3. Tie animals feed on plankton while f ree~Bvimiiiing. One v elig er was observed with an elongate diatom almost as long as its 58 body. The end of the diatom in the gut was observed to be worn off over a period of several days. The larva seemed to be utilizing the contents of the diatom as well as wearing down the outer wall* None of the p_. emertonl larvae underwent metamorphosis in the laboratory. Remarks. _F, emertonl was recently combined with J>. davenport 1 Balch 1899, by Franz and Clark (1972) t and with P^. oonyna Marcus 1957, by Marcus (1976). P^. recondita Schmekel 1965, from Naples was proposed to be the same as emertonl by Franz and Clark (1972), and confirmed by Marcus (197G). Family Onchidorid Idae Acanthodarls pilosa (Abilgaard 1789) (Plate 10and 12, Figure 11) Diagnosis. Adults 7-25 mm in length. Generally yellowish brown with a lighter-colored foot, occasionally dark brown or almost black. Rhinophores and gills retractile into pits. Rhinophores angled posteriorly with about 15 perfoliatlons on the distal one-third. G ills 7, bipinnate, located in a median dorsal position surrounding the anal and renal openings. Mantle covers the body and possesses conical-shaped papillae over the entire dorsal surface, Foot wider than the body, extending from beneath mantle posteriorly, Eye spots deep within animal, not visible. Genital openings located on right side between mantle and foot. Occurrence. In this study, 6 A. pilosa were collected from the seaside of the Eastern Shore and from Cherrystone Creek in the bayside. Distribution on the Western Atlantic is Labrador (Franz 1970) southward to the Chesapeake Bay—these collections establish the southern lim it in the Western Atlantic. It also occurs across the northern Atlantic, 59 south to the Mediterranean Sea (Pruvot-Fol 1954), and in Northern Japan (Baba 1937b)* Seasonality and Food. Adults and egg masses were present in April and May on both sides of the Eastern Shore. A. pilosa Is found on shells In association with bryozoans, sponges, etc., and feeds on a variety of ectoprocts. Morse (I960) reports it feeding on Flustrellidra hispida in New England waters. Other authors have found It feeding on several species of Alcyonldium (M iller 19G1, Graham 1955, Thompson 1964 and others). In this study A^ pilosa was found in association with, and feeding on, Electra cruatulenta. Mating. pilosa shows courtship behavior similar to other dorids. The animals circle each other with the mantle raised, touching and withdrawing. After several minutes they align Juxtaposed, head-to-tall with their genital organs together. They remain in coitus for over 2-1/2 hours. There seems to be a reciprocal transfer of sperm as each animal lays eggs after mating. In the above case, the egg masses were la id 4 days a f te r copulation. Egg Masses and Ejjga. The egg masses are Type A (Hurst 1967), Table 2, with the free edge the same length or slightly larger than the attached edge. Some masses appear smooth and others ru ffled . The masses are generally counterclockwise spirals and aTe greyish white In color, averaging 3 mm high and from 10 to 60 mm or more when unrolled. The egg capsules rarely touch and are in various sizes averaging 104 microns long and 155 microns wide. The eggs are 64-76 microns in diameter (Miller 1958) and there are from 20,000 to 163,000 eggs in an egg mass. These counts agree with the findings of Miller (1958), Thompson (1967) and Roglnskyaya (1961). The eggs hatch in 5-10 days. 60 Larval Development. The larvae liave Type 1 development (Thompson 1967) (Table 3) feeding in the plankton and swimming for several weeks. Wo larvae were observed to undergo metamorphosis in the laboratory - Remarks. One animal from 16 o/oo s a lin ity (Cherrystone Creek) was placed in water of 21 o/oo salinity with an animal collected from 31 o/oo water (behind Cedar Island). Within several minutes the animals were mating. The sudden change in sa lin ity seemed to have no effect on them. During a 2-week period, there were great natural fluctuations in sa lin ity due to a large amount of ra in . In one 8-hour period at the Uachapreague laboratory, the salinity ranged from 12 o/oo to 31 o/oo. None of the nudlbranchs in flowing water seemed to be affected by this variation in salinity. Acanthodoris pilosa ia an amphl-Atlantic midibranch found over the entire coast of Europe (Thompson 1961, Swennen 1961). On the Western Atlantic the species la common in New England. Marcus (1961) reported 2 specimens from Ocean City, Maryland. Franr (1968) quotes Marcus (1961) and states that these animals are not found in New Jersey. In a la te r paper, Franr (1970a) extends the d istrib u tio n of A. pilosa to "Maryland-Virginia". Wass (1972) reports A. pilosa from the Chesapeake Bay, but the animals in his collection labeled A. pilosa are in reality Doris verrucosa. In this paper, specimens of A., pilosa were found in Cherrystone Creek (bayside) and in the seaside lagoon behind Cedar Island. These are the f i r s t v erified specimens of A. pilosa south of Ocean City, Maryland and extend the range to include not only Virginia’s Eastern Shore but the lower Chesapeake Bay as well, A. plloea is similar to Poris verrucoaa but can be distinguished by conical papillae instead of the mushroom papillae of V, verrucosa. Also the posterior angle of the rhinophores and the noticeable foot are distinctive In A. pilosa. 61 Family Gonlodoridldse 0kenla cupella (Vogel and Schultz 1970) (P lates 13 and 2St Figure 12) Diagnosis. Adults 2-5 mm long and laterally compressed * Translucent, with whitish spots (gland cells) and brown or black spots on Its dorsum and rhinophores* Rhinophores possess 3 or more cup-shaped leaves, which vary in number depending on the size and age of the animal. Oral tentacles lacking. Papillae in a row on each aide along pallial ridge, with first papilla anterior to rhinophores and extending to bifurcate pair just posterior to the gills. Mantle present as a palllal veil that forms webbing between p ap illae. A. single club-shaped p a p illa In a median dorsal position occurs juat anterior to the four pinnate branchial plumes. Papillae and rhinophores supported by calcium carbonate spicules produced by the animal. Spicules also form a network over whole body, foot and tall. Body deepest In the cardiac region. Eye spots set deeply in body and most visible from side of animal. Foot not as wide as body but tail becomes as broad as body and capers d is ta lly . Radula composed of 10 rows of 4 teeth , each with a dental formula of 1—1-0-1-1. Teeth angle posteriorly and inner edge of inner lateral teeth possesses 9 denticles. More than 50 animals were collected and observed in this study. The observations agree with those of Vogel and Schultz (1970), Occurrence. Okenia cupella was collected from the York River (Vogel and Schultz 1970), the Chesapeake Bay at Cherrystone Creek and from Wachapreague Channel on the seaside of Virginia's Eastern Shore, Seasonality and Food. Animals frequently came through the sea water intake in the laboratory at Wachapreague during the winter months. 62 Animals were collected from October to March In salinities of 20 o/oo to 30 o/oo. They spawned during the e n tire co llectio n time and appeared to feed on encrusting bryozoans found on sheila. Mating■ The animals aligned in juxtaposition and copulated without extended preliminary touching. Egg Masses and Eggs. Eggs are laid in an oval cylinder attached to the substratum by one side. The egg mass Is of Type D {Hurst 1967) (Table 2). There are approximately 40-50 eggs in the 1 mm long mass. The capsules are arranged randomly in the egg mess and do not touch each other. One egg Is in each capsule and measure 130 microns In diameter. Eggs develop to hatching in 5 days at 16°C. Larval Development. Development is of Type 1 (Thompson 1967) (Table 3) The larvae have a well developed digestive system and almost completely fill the shell. The velum and foot are both relatively small. After hatching, the larvae swam for several days but no individuals underwent metamorphosis in the laboratory. Family Corambidae Dorldella obscura Verrill 1870 (Plate 12, Figure 13) Diagnosis. Adults small (4 mm to 15 mm) round or oval, with no dorsal projections except retractile rhinophores. Rhinophores grooved longitudinally. Notum (mantle) smooth, covering entire body and foot. Melanophores present in mantle, giving animal a spotted appearance. Colors vary from clear cream, with internal structures clearly visible, to gray, brown and finally black, with no internal structures visible. Edge of notum occasionally with slight depression in the posterior region. Foot oval and notched in both front and back, A pair of 63 cephalic tentacles visible ventrally. Branchiae 4 plates located posteriorly between foot and mantle. Reproductive openings located on right side behind head and between mantle and foot. Dental formula 57x6-1-0-1-6, Jaws lacking. Occurrence. These animals are ubiquitous in the study area In salinities above 9 o/oc. Wass (1972) states that I), obscura Is the most abundant nudibranch in the Chesapeake Bay. Distribution is from northern New England to Florida and Louisiana (Marcus 1972a). Specimens were collected from shells, Eostera marina and Alcyonidlum v errilli. Seasonality and Food. J). obscura is present and spawns all year in the study area. Largest animals are collected in January and February. D. obscura feeds on Acanthodesla tenuis. E lectra cru atu len ta. Membraninora sp. and Alcyonidlum verrilli (Franz 1967* Cory 1968). It shows preference for the food on which it la collected. In the winter months, A. v e r r i l l i seems to dominate the food supply (Vogel unpublished m s.). During feeding, the nudibranch puts its lips over the opening of the zoo id and sucks out the soft parts of the bryozoan using the buccal pump. The radula is extruded and is used for rasping the soft parts from the zoold. The backward stroke of the radula seems to be the most important one (McBeth 1968). Mating. I), obscura has no specific courtship procedure. Two animals lift up the edge of their mantles, come together and copulate. There seems to be reciprocal transfer of sperm as both animals lay eggs after copulation. Eft a Masses and Eggs. Egg masses, described by Franz (1967), are flat, white spiral of Type B (Hurst 1967)(Table 2). The mass Is laid in a counterclockwise spiral starting from the outside. Occasionally there 64 is a ’pile up* of eggs In the center after the spiral is complete. The eggs are not in a string inside of the mass, however, occasionally striking geometric designs occur. There is a range of 108 to 2870 eggs in the masses counted, with one egg in each egg capsule. The width of a single strand averages 1 mm and when the entire mass is uncoiled and extended, it measured 4-25 mm in length. Larval Development. The eggs reach trochophore stage in 48 hours and are veligers with shells in 3 days, Veligers hatch in 3-5 days depending on the temperature. The veligers are of Type 1 (Thompson 1967) (Table 3) which indicates the larvae feed in the plankton. Ho larvae were raised to metamorphosis In the laboratory. Successful rearing of I), obscura through one complete generation was performed by Perron and Turner (1977). They reported an egg to egg generation time of 26 days at 25ftC. Remarks. On two different occasions, specimens of I), obacura appeared to have autotomized the edge of the mantle. In these specimens the head, body, g ills and foot were v isib le. The rhinophores were s t i l l encompassed by the mantle. They resembled Crepidula. with the shell covering only a small portion of the extended body. Cases of nudibranchs with autotomlzed mantles have been reported (Hyman 1967), Apparently this phenomenon occurs during stress of manipulation. Other opistho- branchs were reported as autototnizing and then regrowing the posterior sections (Parona 1B91, 1894; Cucagna and Nusbaum 1915, Hyman 1967 and others), but the observed J). obscura did not regenerate. All the autotomized animals died shortly after being brought into the laboratory. There were many I), obscura collected that remained intact and only two occasions in which they did not. All samples were treated essen tially 65 the same. No explanation for these 'different 1 animals was suggested. IK obscura was the only animal studied that autotomlzed Its mantle, although several of the animals with cerata autotomlzed their cerata when stressed or when they were preserved without being relaxed, D. obscura was also the only species observed that periodically sloughed off the mantle epidermis, a colorless sheet of cells which Is entire except for holes for the rhinophores. This shedding docs not seem to be related to stress but Is possibly related to growth of these c re a tu re s . Family Dendrodorididae D orlopsilla pharpa Marcus 1961 (Plates 14, 21, 22, 23, 24, Figure 13) Diagnosis. Adults yellow to yellow-orange, with brown spots on mantle. Body oval in shape, mantle completely covering foot. Four retractile bipinnate gills surround anus. Rhinophores perfoliate and retractile. Spicules noticeable on mantle especially around the edge. Foot broad and rounded posteriorly. Mouth small w ith a short tentacle on either aide. Largest animal 22.5 mm in length. No Jaws or radula present. Reproductive openings located on anterior one-third of right side between mantle and foot. Penis everslble and armed with hooks (Marcus 1961). Occurrence, I), pharpa occurs on the seaside of the Eastern Shore of Virginia behind Cedar Island, in the seaside lagoons and in the lower Chesapeake Bay. D istribution is from Sapelo Island, Georgia to Chesapeake Bay (Marcus 1972a) and southern Cape Cod (Morse 1974). The animals were found on hard bottoms, on shells that contain Cliona celata Grant, the boring sponge, and occasionally in pieces of free- 66 living (i. celata. It was also found in oyster shells that were on in te r tid a l rocks, but always on the under side of the exposed sh ells. None uas found completely desiccated. Seasonality and Food. The adults are abundant and large enough to be seen easily from September to June or July. Young of the next generation are present but very difficult to see in July and August. More than 50 adults and many Juveniles were collected in this study. D. pharpa feeds on the boring sponge C^. c e la ta . It feeds by sucking the sponge soft parts into its mouth with its buccal pump. Any spiculea Ingested are passed through the digestive tract and not utilized by the animal. Mating. D_. pharpa has a specific type of courtship and mating behavior, as do most nudibranchs. Two animals crawl close to each other touching their mantles. Each touch causes retracting of the gills and rhinophores* This circling may take several minutes. Copulation occurs when the pair align juxtaposed and Join their genital openings. The mantle is lifted to allow penetration by the other animal. A simultaneous transfer of sperm occurs. Copulation lasts approximately 10 minutes but can be longer depending on the individuals. Egg laying does not occur immediately after copulation. The interval may be several hours or several days, which indicates that the sperm is viable after being stored for various periods of time. In summer, the adults will occasionally lay eggs when brought into the laboratory. Egg Mass and Eggs. The egg mass is a cylindrical clockwise spiral fastened to the substratum along one aide {Type B, Hurst 1967) {Table 2). A la te r a l view shows a s p ira l cone-shaped stru c tu re with the point in the center resembling a traditional Chinese "coolie" hat. The eggs are dark yellow when laid and become lighter yellow after a feu 67 houra. The mass is laid from the center of the spiral to the outside. There is usually one and rarely two eggs per capsule. The egg capsule walls are smooth and frequently touching. The eggs are 190-234 microns in diameter; the egg capsules 290-450 microns. An egg mass averages 500 eggs, but can be as low as 1 0 0 In early and very late egg masses. Larval Development. The overall view of D. pharpa development ia described as direct or arrested development (Karens, personal com munication) , Morse (1971) suggested this type of development be called development Typo 3 after Thompson (1967), (Table 2) indicating the animal crawls directly from the egg mass as a Juvenile to begin benthic life. The embryo within the egg capsule recapitulates all the stages of development including a shelled veliger before it advances beyond that stage and hatches as a juvenile that has cast off its shell and undergone metamorphosis. The blastula stage is reached in 2 days (Table 7) . Four days are needed from the blastula stage to the trochophore stage, and 8 days from the time the eggs are laid, for the appearance of the shelled veliger. Eye spots are evident at this time. The foot is quite enlarged and is cupped over the shell. The mantle begins to reflex and covers the sh e ll lik e a co llar and the velum is reduced. The mouth is noticeable, ciliated and square. By the 10th day, the eye spots are very pronounced. There is now evidence of the gut even though the yolk renders most of the animal opaque, A longitudinal dark streak appears on the foot. The mantle continues to grow over the shell until time of hatching (Plate 2l)* There is a red spot inside the shell, and pigment spots in the mantle. Rh inop ho re rudiments are present on the 11th day. There are no retractor muscles present 6a in the veligers, and at no time do they look like they could contract completely into the shell. No operculum is present in the larva. The animals start casting off their shells Inside the egg capsules by the 13th day. The egg capsule collapses around the larva and after several hours, the animal emerges from the egg capsule as a s h e ll-le s s juvenile. Hatching takes place over a period of several days in any one egg mass. The velum of the hatching larva is reduced to two small lobes, and the animal is covered with cilia. The larva casts off its shell by crawling on its foot and extending more and more of its body out of the shell until it is held by tissue at only one point. This is also peeled off from the shell and the animal crawls away. Some animals hatch from the egg capsules before they cast off the shell (plate 2 2 ) . Juvenile Development. After the Juveniles hatch, they find an opening In the egg mass where the mucus wall has disintegrated, allowing them to crawl atop the egg mass. They stay on the egg mass for several days after hatching. Even though there seems to be no synchrony in the cleavage pattern, some hatching order is evident. Juveniles on the outside edge of the egg mass emerge f i r s t as hatching works progressively toward the center of the egg mass, with the portion of the egg mass that was laid first hatching last. The central whorls of the egg mass contain larvae with a large velum when the outer whorls contain hatching juveniles. The central animals may emerge over a week after the outer ones. This could possibly be due to a smaller amount of oxygen reaching the center of the mass. The eye spots are very noticeable in the larvae and also in the Juveniles. The foot is elongate and extends beyond the mantle posteriorly (Plate 23) . The mantle is oval-elongate with notches at 69 both the anterior and posterior part (Plate 3 3 ) . Hatching siz e ranges from 0.250 mm to 0.600 mm. Some of the young possess spicules before they hatch, but most do not acquire spicules before they are three days old. The spicules are made of amorphous calcium carbonate (Odum 1951), anti formed in a progressiva pattern (Plate 23}- The first spicules are simple and pointed at both ends, similar to the oxeas of sponges. They form a fish bone pattern in the juvenile that extends dorsally from the eye spots to the anal region. The spicules are crisscrossed with other simple spicules by the next day. Later spicules with a tripod at one end are formed (Plates 23 ant^ 20 . These are located along the outer margin of the mantle, and gland cells are now also present along the edge of the mantle. The eye spots are very noticeable in the newly hatched ju v e n ile s. As the anim al grows and becomes thicker, the eye spots are deeper in the body and leas noticeable even though they are still evident in the mature adult. The rhinophores retract into pits at around the fourth day after hatching. The animal becomes dark brown in the region of the presumptive anal opening. This evaginates and eventually produces an opening. The brown material is possibly metabolic wastes. At the end of 4 weeks the animals possess two retractile gills, a wide foot, spicules, shiny gland cells, retractile rhinophores and black eye spots. Oral tentacles are present when the nudlbranchs are up to 4.5 mm in length. At approximately 7 weeks the animals have acquired two additional gills (they now have 2 large and 2 small gills). There are four leaves or perfoliations on each rhinophore, tubercles supported by spicules on the dorsal surface, and dark pigment spots on the back. The foot remains longer than the 70 posterior mantle (Table 0)* The number of leaves or p erfo llatio n a on the rhinophores is probably not a valid taxonomic feature for nudibranchs, as the number of perfoliationa in these animals increases with size and age to 15 or more (D, pharpa) . I t is possible that the number of leaves also changes in other anim als. The juveniles are activ e and feeding from about 3 or h days to a week after hatching. At 6 or 7 weeks, they spend time on the sides of the culture bowls and in the surface of the water. If the animals are not fed after hatching, they become a very pale cream color and transparent. They remain shiny due to the presence of spicules. If the animals are fed, they become increasingly darker until they become the same color as the sponges on which they feed. At the end of 2 months the largest animals are almost 5.5 mm long. By the time they are 3 months old, they range from 5 to 7 mm long. When they are k months old the largest ones are 12 mm long, and at 5 months they are close to maturity in size. At this time, which Is usually November and December, they range from 11 to 19-20 mm long (Figure 5) . The life span of I), pharpa Is from 9 to 13 months. Mature adults mate and lay their eggs from May to July and then die after spawning- Eggs are laid on s h e lls containing C^, c e la ta . Eggs hatch after 13-20 days and the young emerge as metamorphosed juveniles. Spicules develop in a matter of days after hatching. Juveniles begin feeding several days after hatching and grow rapidly, reaching maturity in h or 5 months. The animals over-winter as non-mating adults. The adults begin mating in the spring, maturation depending apparently on SIZE IN mm iue . eainhp f li t ae n ueie Dorlopallia juvenile in age to eliie of Relationship 5. Figure 14- (Hdtching ar.25mm} pharpa. G I MONTHS IN AGE 3 6 7 Table 7. Development of D orlopallia pharpa at 25-27*C. 1 st cleavage 6 hours b la stu la 2 days trochophore 6 days v e lig e r 0 days mantle reflexing over shell 10 days rhlnophore rudiments present 11 days shell cast off 13-19 days hatching 13-20 days spicules formed 3 days after hatching (occasionally before hatching) 72 73 water temperature and not Influenced by photoperiod. After mating and egg laying, the animals die. Animals kept in the laboratory compared favorably in size, color and activities with animals brought In from the wild for comparison. Some animals were kept over winter in unaerated bowls at room temperature {IB-21aC), some were kept In unaerated bowls on the wet table with ambient water temperatures {0-4 or 5“C), and some were kept in flowing water traya (0 to 4 or 5&C). The ones at room temperature continued to feed and move around. These animals seemed to have accelerated maturity and started to mate in late February. The animals in ambient water did not begin to mate until late April and early May. The earLy maturing animals died at an early age, Februaryand March rath e r than in June or July. Some developed lesions on the right dorsal side just anterior to the gills, lesions attributed to early senescence. Some of the early mating animals also laid viable eggs. Mortality rate decreased when some of the early maturing animals were placed on the Wet table at ambient water temperatures. Some of the early egg masses developed normally while others did not. Egg masses were smaller than normal and the animals died soon a fte r mating and egg laying. Animals held continuously on the wet table or in flowing water tray3 did not start laying eggs until May. Remarks. The advantages of th is type of development are: 1) Fewer eggs are needed, as most of the eggs hatch. 2 ) the eggs hatch at an advanced stage, elim inating the very vulnerable free-swimming larv al stage, and increasing chances of survival. 3) Mo food is needed in the larval stage. 4) The young are independent of outside food supplies for a longer period of time than ones that have a free-swimming larval 74 stage. The disadvantages of this type of development are: 1) The eggs require a long hatching period. 2) They are vulnerable in the egg mass. 3) The young cannot survive outside the egg mass if it is disrupted, b) These eggs are expensive to produce, in that they need a lot of yolk to enable them to develop. Family Dotoidae Doto coronata (Gmelin 1791) (Plate 15, Figure 12) Diagnosis. Specimens range from 5 to 11 mm in length. Adult aeolidifom, base cream colored with red pigment spots. Pigment spots on body vary from very few to so many that the whole animal appears dark red, Cerata cream-colored, 5-7, on each side of the back. Cerata covered with raised papillae pigmented red, which turn black when animals are preserved. Rhinophores translucent pale, slender cylinders retractable into trumpet-shaped encompassing sheaths. Sheaths normally cover at least one-half of rhinophores. Foot as wide as body. Eye spots not visible in the mature adult. Anal opening dorso-lateral. Reproductive openings beneath the first ceras on the right side, Mo oral tentacles present. Occurrence. Forty specimens were collected from the mouth of Cherrystone Creek in the Chesapeake Bay. The species occur in the Western Atlantic from Greenland to Hew Jersey (Franz 1970). The animals collected in this study extend the range of I), coronata southward to the lower Chesapeake Bay. This species is amphi-Atlantic and is found from Denmark to the Mediterranean Sea (Pruvot-Fol 1954, Franz 1970a). Seasonality and Food. I), coronata feeds on more than 20 species of hydroids (Thompson 1964). These include species of Bougainvillla, 75 Obelia, Campanularfa. Tubularia and Bertularia. D. coronata was co llected in A pril and May samples in 1975. The animals were spawning a t the time. Swennen {1961) observed more than one spawning a year and Miller (1962) stated there may be as many as 4 spawning periods a year for D, coronata near the Isle of Man. Mating. The mating and egg development of IJ. coronata has been studied by different authors in recent times. Kress (1975), compared the larval development of three species of Doto In Europe — Doto coronata. I}, plnnatif Ida and D, fragilis. Several other authors make comments on Che l i f e cycle, Including M iller (1962), Swennen (1961), Thompson (1967) and C lark (1975), There does not seem to be any elaborate courtship procedure before mating. The animals aligned juxtaposed 'head-to-tail 1 and curved together during copulation. A simultaneous transfer of sperm is evidenced. Egg Masses and Eggs. White eggs are laid in a narrow ribbon attached to the substratum along one edge, Type A (Hurst 1967) (Table 2). The free edge is the same length as the attached edge so there is no rippling of the mass. One or two eggs occupy each capsule. The capsules tend to be oval but occasionally they are drawn out into a cylindrical shape or jammed together into a square, Kress (1971, 1972) indicated the egg capsules get larger after they have been laid. One interesting observation of D. coronata development is that the eggs do not develop synchronously. Those laid first develop faster than those in the opposite end of the egg mass. There can be as much as 2 days difference in developmental stages and time in the extremities of an egg mass. 76 Larval Development. Eggs developed normally to hatching in about 9 days at 13.5 to 15.5°C. Eggs laid at the higher temperature of 17°C developed to a certain stage and then stopped. The embryos would undergo cell breakdown and dissociation. Very few eggs would progress to the veliger stage. Apparently lS^C must be approaching the upper temperature limit for egg development for this species. Kress (1975), Hadfield (1963) and Thompson (1967) all reared I), coronata eggs at 10 to 15DC. The larvae are planktotrophicof Type 1 (Thompson 1967) (Table 3). Hone of the larvae underwent metamorphosis during the study. Family Cuthonidae Tenellja adsperaa (Nordmann 1845) (Plate 16, Figure 14) Diagnosis. Adults small, aeolldiform, about 5-7 mm long. Color translucent white, with dark pigment spots on the body and cerata. Cerata arranged In 5 to 7 groups of 1 to 3 on each side. Digestive gland * liver * brownish or yellowish inside each ceras. Cnldosacs present in the tips of the cerata. Eye spots located behind solid, simple rhinophores. Oral tentacles absent, but occasionally there is a small oral veil. Foot as wide as the body, anterior edge rounded, and posterior end tapered to a short tail. Anal opening located in scleioproctic position, (Posterior to the second group of the anterior right hepatic diverticulac and anterior to the posterior left hepatic diverticulac.) Occurrence. More than 50 T. adsperaa were found at several localities in the Chesapeake Bay at s a lin itie s averaging 12.5 o/oo, Rasmussen (1944) studied some T. adspersa in salinities of 20 o/oo. The Western Atlantic distribution for T_. adsperaa is from Chesapeake Bay to Sao Paulo, Brazil (Marcus 1972a). Further distribution is from Lofoten and Finland to the Mediterranean Sea (Pruvot-Fol 1954), Black Sea (Roglnskaya 1970) and Japan (Baba and Hamatani 1963). Seasonality and Food. T^ adapersa is found year round in the study area. The adults feed on a variety of hydroids including Cordylophora la cu b tris . Protohydra leuckartl and Obella dichotoma (Thompson 1964). They also feed on Bougainvillea sp. They attack the hydroid polyp and engulf the en tire animal from the o ral end. Mating. T_. adsperaa has little distinctive courtship behavior. It moves to the head-to-tail position with ita mate, its genitalia enlarged and extended, and copulation takes place immediately. Both animals copulated as male and female. h£fi_ Mass and Eggs. Eggs are laid in an oval sac, 3 to 4 mm long and to the substratum at the center (Type D, Hurst 1967) (Table 2), There are from 3 to 175 egg capsules per egg mass, each containing 1 egg which is from 130 to 200 microns In diameter. The egg mass size, number of eggs and size of the eggs, as well as the time to hatching, depends on temperature and sa lin ity (Rasmussen 1944). Larval Development. The veliger lias an inflated shell, a small velum and a very large foot. Eye spots are present a short time before hatching. Rasmussen (1944) noted purple-black pigment in the larvae around the eyes, foot and liver. The animal fills about two-thirds of the shell. This species is very easy to rear in the laboratory. The animals from Chesapeake Bay hatch at 4 days, swim for 2 hours to 2 days and then cast off their shell and undergo metamorphosis. Some individuals from the same egg mass cast off th eir sh ell a fte r hatching 78 from the egg capsule and crawl from the mass as young juveniles. In the Baltic, the egg a hatch after 4-9 days and swim In the plankton for up to 5 days (Rasmussen 1944). Rasmussen (1944), also occasionally observed juveniles crawling from an egg mass. The species exhibits development Types 2 and 3 (Thompson 1967) (Table 3 ). Juvenile Development. The dorsum of the juveniles is rectangular at first, but rapidly becomes elongate-triangular, budding rhinophores and one pair of cerata. The juveniles are whitish translucent with two irregular black pigment spots and two black eyespots on the dorsum. They are completely covered w ith c i l i a . Growth process is sim ilar to that described for Tenellia fuscata in this paper. The animal is equipped with radula and Jaws from hatching. At the end of 2 to 3 weeks, the young animal is reproductively mature and has mated and la id eggs. Remarks. Some controversy has arisen over the correct name of this species. The name Tergipes adsperaa was assigned in 1845 by Nordman and has been little used until recently (Roginskaya 1970), while the name Embletonia p a llid a Alder and Hancock 1854, has been used continually by western countries since that time. There is also another name (Tenellia vent11abrum Dayllel 1855) that has been applied by some (Pruvot-Pol 1954, Abbott 1974) to that species. Lemche (1973) has proposed that T. adsperaa be suppressed as a notnen obi it urn and Tenellia pallida be placed on the Official List of Specific Names. Roginskaya (1974) commented on Lemche1s proposal (1973) and stated that the name T. adsperaa meets the requirements of the "50 year rule", Article 23(b), International Code of Zoological Nomenclature (1964) , which indlcatea that the name must be published more than 10 times in the la s t 50 years 79 by a number of authors to be considered a working name. This controversy has not been resolved as yet by the ICZN. Tenellia adsperaa is used here as the current valid name. Tenellia fuscata (Gould) (Flate 16, Figure 1 4 ) Diagnosis. Adult small (3-7 ram) eolid with short oral tentacles, 1 pair of rhinophores and cerata containing cnidosacs. Cerata arranged in 5 or 6 groups of 2 to 4 on each side of the dorsum. Heed broad, forming short oral tentacles. Foot as wide as body, rounded in front, and tapering to a short tail. Color translucent white, with dark pigment spots on dorsum and cerata. Eye spots located behind rhinophores. Digestive gland diverticula slightly darker than cerata. Anal opening acleioproctic, in interhepatic space. Radular ribbon made up of approximately 19 rows of 1 tooth each. Occurrence. ^T. fuscata is found in the Chesapeake Bay and on the seaside of Virginia's Eastern Shore. Western Atlantic distribution is from New England to Virginia (Franz 1970). Seasonality and Food. Animals are collected throughout the year in salinities ranging from 14.5 0 /0 0 to 30 0 / 0 0 . It is collected in bydroid fouling on shells, pilings and Zogtera. It feeds on a number of hydrolds, including Garvea cerulea and BouRainvilla spp. More than 50 specimens were collected in this study. Mating. The adults copulate after a courtship of one or two contacts of cerata or tentacles and alignment in juxtaposition. Both partners lay eggs afterwards. Egg Masses and Eggs. Eggs are laid In a kidney-shaped mass attached to the substratum by a central stalk, (Type D, Hurst 1967} (Table 2 ). 80 The eggs are white, large (175 microns), yolky and enclosed in separate capsules. There ate 4-50 eggs in each egg mass. Larval Development. Veligers are present in the egg capsules after 3 days and hatch In 3 to 5 days. The veligers usually swim but do not feed. The larvae cast off their shells and undergo metamorphosis from a few hours to 3 days after hatching. Some of the larvae do not develop a shell at all or cast off their shell before hatching. This species has development Types 2 and 3 as described by Thompson (1967) (Table 3), These individuals are usually found in egg masses having shelled veligers that hatch and swim before losing their shell. The shell is inflated and unmarked. The veliger fills the entire shell before hatching. Juvenile Development. JuveniLes are triangular, covered with cilia and possessing Jaws and a radula from metamorphosis. The larvae do not feed, but the juveniles began to feed on adult food as soon as they undergo metamorphosis. The visceral mass of the newly-emerged juveniles is located in a dorsal hutnp. After a day, the hump becomes less noticeable as the visceral mass settles in the animal. The rhinophores and one pair of cerata (anterior right and anterior left hepatic lobes, anterior to the heart), bud about 2 days after metamorphosis. The cerata are complete with digestive gland diverticulae and cnidosacs. Initial cerata always bud in pairs (Table 8). The second pair of cerata appears posterior to the heart and contains digestive gland diverticulae from the posterior left hepatic lobe. The third and fourth pairs of cerata bud simultaneously, with the third pair anterior to the first pair and the fourth pair posterior to the second pair. After the initial cerata are formed, the appearance of cerata is 81 rapid. The animals become mature* mate and lay eggs ^ or 5 weeks after hatching. Tenellia sp. (Plates 1 5, 1 7 and 26, Figure 14) Diagnosis. Small, aeolidiform, measuring 3 to 5 mm long. Head small, rounded, and body larger, almost oval. Rhinophores simple cylinders. Cerata arranged in clumps on each side of dorsum. Two cerata present in first 1 or 2 groups, 1 ceraa in each of others. Eyea located in clear area behind rhinophores. Anal opening dorso-lateral. Dorsum pigmented with dark melanophores - more or less - on front of head, between rhinophores and all on the dorsum and cerata. Foot very narrow, less than one-third width of body. Anterior end of foot enlarged, wide as head, and notched anteriorly Just behind mouth. Tail short, broad and pointed. Adult about as high as broad. Occurrence. Seven animals were collected from Wachapreague Channel (salinity 30 o/oo) and Cherrystone Creek (salinity ~23 o/oo) . Seasonality and Food. The adults were present and spawning in November through the end of January. Tenellia sp. feeds on different hydroids including Tubularla crocea. The feeding behavior is different from other eolids. A Tenellia sp. , was put on a hydroid stalk, and immediately began to bite into the bottom end of the stalk and suck at the hydroid with its buccal pump. It fed on the hydroid for about one-half hour; then slowly worked towards the polyp end of the sta lk . I t b it Into the sheath just beLow the polyp and started pumping there. The nudibranch would pump for a time (with the hydroid tentacles moving in unison, probably due to hydrostatic pressure) and then stop. In the resting interval, the cerata would pulsate. Then the animal would Table 8 , Appearance of dorsal appendages In Juvenile Tenellia fuscata. Type of appendage Number Location of appendages rhinophores 1 pair top of head cerata 1 pair one on each side, anterior to heart cerate 1 pair one on each side, posterior to heart cerata 2 pair one pair anterior to the first pair, and the other posterior to the second pair cerata pairs the remaining cerata bud in pairs posterior to last cerata and beside existing cerata 82 S3 s ta rt pumping again u n til it had removed almost a l l the hydroid from its theca. One Tenellia sp. could consume a hydroid polyp and stalk in about 2 hours. Most eollds ohserved attack their prey from the oral end and either engulf the entire animal in one stroke or continue to attack the cnidarlan u n til the whole animal is consumed. Mating. Mating of Tenellia sp. was not observed, although the animals laid several egg masses in the laboratory. Egg Hass and Eggs. The egg mass is of Type C (Hurst 1967) (Table 2), a Jelly bag attached to the substratum by a tnucue thread. The egg mass is approximately 1.3 mat long and 0.8 mm wide, with "creases" in the outer membrane. The eggs are white and each is contained within an Individual capsule. The egg capsules touch each other but are not arranged in a string. There are approximately 20-50 eggs in an egg mass. The eggs are rather small at 76 microtia in diameter, and the egg capsule is smooth and 119 microns in diameter. A comparison of the eggs of the three species of Tenellia can be seen In Table 10. Larval Development. The later stages of development (to hatching) are considerably different in Tenellia sp, from the other species of Tenellia. The animals develop a thick layer of cells on the inside of the shell, with the veliger body remaining concentrated near the aperture. The shell is flattened laterally and gives the larva the appearance of an oval with an aperture on the side. As the animal develops, the shell elongates (or increases) until the final pre-hatching shell forms. This shell is Inflated, with the aperture on the anterior end. The animal always seems to be concentrated near the aperture except for the heavy layer of cells (mantle) that coats the inside of the shell and a large retractor muscle. The foot and velum remain 04 proportionately email {as compared to other Tenellia) until after hatching. After hatching, the animals swim for several days. At about 1 0 days after hatching, the mantle begins to 'peel away 1 from the Inside of the sh ell and the foot becomes enlarged. The velum Is still present along with what appears to be rhlnophore rudiments. The animals swim with the body erect and the shell beneath. When they stop beating their velar cilia, they sink in the water column very quickly. The animals seem to be feeding in the larval stage. None of the veligers underwent metamorphosis in the laboratory. Remarks. This animal is different from Tenellia fuscata and T. adspersa in these ways: T^. fusesta and ^T, adspersa both have a broad foot as wide as the body, while Tenellia sp. has a very narrow foot. Tenellia sp. has a dorso-lateral anal opening; the other two have a lateral acleioproctic anus. The radular teeth in T_. fuscata and ^T, adspersa contain a slightly, to very prominent, central cusp with smaller canticles on each side. In Tenellia sp., the central cusp is noticeable but denticles on each side are as long as the central cusp. The egg development is also different in Tenellia sp. Family Favortnidae Cratena p lla ta {Gould 1870) (Plate 19, Figure 15) Diagnosis. Adult aeolidiform, up to 30 rani long. Cerata contain a cylinder of usually brownish digestive gland internally, and two silver-colored rings externally near the distal end of each ceras. An interrupted carmine stripe present down the dorsal surface and on either side of the head. Carmine stripe on back outlined by a dotted shiny white line connected between the stripes. Oral tentacles, Table 9, Comparison of the eggs of three species of Tenellia in the Chesapeake Bay 01 d 0 ts <10.0 01 ID td >4 a o t in o a a ton nod no 00 m m A a 51 3 S - X X 4-» 4-1 1 VI 01 o o C 01 U 01 01 oi u 0 0 1-1 1-1 0 0 a o 1 01 VI Ih S l u *j ^ r-l u a x U u m ffl >t a a 'H 11 (A BA P. <1 -31 N ( O l - T n o iH (O(M (A X CT. "O M LO X 14-1 ■H — & i—1 H 63 iH +J +J 4-i m » 3 a 2 ti e? 1-1 CD [A S 01 0 CIS o e P*i I « ® r-. 141 TJ 01 fl n L ut Hi nA j H 01 a nj (vjm in ■o X -3 simple solid rhinophores and cerata present- Cerata arranged In 4 or 5 horseshoe-shaped rows and 1 or more lines of cerata on either side of dorsum. Number of rows of cerata dependent on size of animal. Head set from body by a slender neck. Eye spots located behind rhinophores. Foot, as vide as ot slightly narrower than body, drawn out Into two lateral triangular processes anteriorly and tapered to a slender tall posteriorly. Anal papilla located on right side In acleioproctic position, within second horseshoe of cerata. Reproductive openings beneath first horseshoe of cerata on right side. Jaws clear to light yellow and serrated on masticatory edge. Dental formula 19-2lx 0 - 0 - 1 - 0 - 0 , with central tooth having a large central cusp with 4 to 8 smaller cusps on either side. Occasionally some smaller cusps b ifurcate. Occurrence- In this study, more than 50 animals were found at Wachapreague and Wachapreague Inlet. The species Is reported from Nova Scotia to North Carolina (Abbott 1974). It Is abundant in summer and fall, especially on the thecate hydrozoan Tubularla sp. Seasonality and Food. Adults are found in the study area during most of the year. Animals feed by climbing the hydroid stalk and grasping the polyp with the anterior ends of the foot. They then suck out the soft, red, inner parts of the hydroid. The digestive tract of the nudibranch turns the same color as the food except for the hepatic lobes In the cerata. Adults are also agresslvely cannabalistlc in the laboratory when crowded. C^. pilata was observed feeding on the sea anemone Dladumene leucolena (V e rrlll 1885) and on hydroids in the genera Bougalnylllia and pennaria (Kepner 1943), 87 Matins- Adults carry on a short courtship behavior of touching before copulating. The animals line up, head to head, raise off the substratum and Join the anterior portions of their feet, their copulatory organs extended, and tulst around each other to facilitate penetration. Coitus lasts 1 to 2 minutes before the animals move apart. Both adults lay eggs after mating. Egg Masses and Bags. Eggs (Type 3, llurst 1967) (Table 2) are laid in the form of a spiral with secondary loops and are attached to the substratum by a mucus ribbon that lacks eggs. The egg mass contains approximately 4,000 eggs enclosed in a jelly cylinder within the mass. This spiral cylinder is pinched together at intervals and sub sequently forms capsules containing from 1 to 4 eggs. Usually the constrictions form distinct capsules attached to each other by a thread, but occasionally the constriction is indicated by a very slight indentation in the cylinder or by complete isolation of an egg capsule. The eggs develop in three days at 28 o/oo to 30 o/oo s a lin ity and 23 to 28°C. Larval Development. The development (Table 3) is of Type 1 Thompson (1967). The larvae have uninflated shells and an operculum. Vellgers are well differentiated and feed- There are no color markings, except the appearance of red spots at the base of the velum just before settling- A small number of larvae were observed without shells, or casting off shells. The animal became detached from the shell by a series of rapid thrusts and short periods of rest. They would finally detach or * unpeel’ the retractor muscles from the inside of the shell. The observed 'shell-less' animals still possessed a velum and could swim- Observations were made of animals crawling on hydroida placed in the containers for that purpose. The Juveniles were triangular or oval-shaped and covered with c ilia . Hone of the metamorphosed animals were observed past this stage. Ccatena kaoruae (Marcus 1957) (Plate IB, Figures 6 and 15) Diagnosis. A stout aeolidiform animal with short neck and simple rhinophores and oral tentacles. Dorsum possesses groups of cerata, each containing up to 17 cerata. Anterior 3 or 4 groups in simple horseshoe shapes and posterior groups arranged in rows. Number of groups of cerata and number of cerata in each group depend on size and age of animals (Figure 6), Foot wider than the body and drawn out into short tentacles in front and tapered to a point posteriorly* Anus located in cleioproctic position within the second horseshoe of cerata on the right hand side. Color translucent with drab grey- brown hepatic diverticulum. Circles of white occur at tips of cerata and faint-to-bright russet stripes on head, one stripe on top of head and one on either side. Color in the hepatic diverticula becomes almost salmon color when fed Cyanea capillata medusae. Occurrence. (^. kaoruae was collected in the Chesapeake Bay at s a lin itie s from 9 o/oo to 20 o/oo and was rarely found In s a lin itie s to 30 o/oo on the seaside of V irginia's Eastern Shore. Marcus (1972a) reported the animal from Texas and as far south as Brazil. Seasonality and Food. The adults are collected throughout the year, with abundance peaking from June to mid-December. Very small adults (under 4 mm), were collected in June, November, and eatly December. Adults (up to 30 mm, but usually 15 to 22 mm) spawn in May and June and September and October, with egg masses being especially numerous o <£> O if O CU o o s cr Lxl o o l i . fD O cr UJ o p* o r\l . . The relationship of Cratena kaoruae size to number of cerata. ** 6 Figure Figure oin o O o ww N! H19N31 90 during September to November. The animals are found In association with a variety of substrata, Including sand and mud bottoms, Ulya and other marine algae, eel grass and other aquatic marine plants, hydroids, sea squirts and espeically on oyster shells. The nudi- branchs feed on the scyphistoma stage of Chrysaora quinquecirrha and hydroid polyps in the wild, with quinquecirrha polyps being the preferred food in the Chesapeake Bay. Adults are also fed chopped manubria and tentacles of (]. qulnqueclrrha and Cyanea c a p llla ta medusae in the laboratory when polyps are not available. Hating. The adults have a sp ecific and elaborate courtship and mating behavior. Animals are ready to mate when the abdominal area is completely filled with mature ova. The nudlbranchs are quite antagonistic and if non-mating adults are placed in the same bowl, one would attack and cannibalise the other. Mature adults exhibit sensi tivity to each others presence, and seldom crawl far apart. At first they circle each other and ruffle their rhinophores and cerata. Then they begin touching each others’ cerata, rhinophores and tentacles, recoiling after the first few contacts (Vogel 1969, 1970), This touching becomes more frequent as the animals move in increasingly smaller circles. After 2 to 10 minutes of circling, the animals touch the anterior lobes of their feet and heads together, with their distended penis is extended and the vaginal openings noticeably enlarged. The animals raise up from the substrate about one-fourth of their length, face each other, and join foot to foot, and with a slight twist of their bodies, bring their genitalia in conjunction so that the penis of each animal is inserted into the vaginal opening of the other. The two animals are thus twisted around each other during copulation with the cerata markedly spread outwards, ao that they look like one Individual and very much like a single ball of cerata. The two nudibranchs stay in this embrace for from one-half to six and one-half minutes. During this interval, there is simultaneous transfer of sperm. When the copulation time is very short, the nudibranchs usually repeat the courtship and copulate as many as 4 times in succession. The genitalia are clearly visible and enlarged at the end of copulation. A film of white mucus surrounds the genital apparatus after copulation and is eaten by the animal. During the summer, J], kaoruae began laying egg masses within an hour or two after mating. In winter however, from one to five days might pass before egg laying occurs. As many as five egg masses are laid by one nudibranch after a single copulation. Copulation appears to be needed for egg laying although sperm can be stored for several weeks for subsequent spawnings. Egg Mass and Eggs. Eggs are laid at various times during the day or night in a gelatinous cylinder that has a characteristic spiral with secondary loops, and is attached to the substratum by an egg- le ss mucus band (Type B, hurst 1967) (Table 2). Egg masses are often found attached to algae, hydroids or other sessile organisms. The length of these egg masses ranges from 40 nun to 150 turn, with the average being about 65 mm. The largest egg masses are deposited by the largest individuals. It takes one half to two hours for C. kaoruae to deposit an egg mass. Fewer eggs occur in each successive egg mass deposition. After the animal stops laying eggs it does not mate again u n til the whole abdominal cavity is refilled with mature eggs. The number of egg capsules in the gelatinous mass can exceed 9 2 1,000. The egg capsules are arranged in a tight spiral with each capsule containing from one to five eggs ranging in size from 65 to 100 microns. Whan two or more eggs occur in the same capsule, each egg is s lig h tly sm aller than when only one is present. Development begins as soon as the eggs are laid. Since it can take two hours for an egg mass to be laid, the eggs laid first are already developing before the last part of the mass is laid. It is found that eggs will not develop outside the egg mass past early biastula stage, because when removed from the egg mass for study, development terminated quickly, followed by disintegration. This indicates that the function of the gelatinous portion of the egg mass may be osmoregulation or protection from bacteria, larval Development, The times for the developmental stages are listed in Table 10. Cleavages are holoblastic and spiral, but not necessarily synchronous. Development is of Type 1 (Thompson 1967) (Table 3), hatching takes place three or four days after the eggs are laid. The egg capsule surrounding the veliger, or veligers, collapses, leaving the animal(s) tightly encased. The veliger beats its cilia and relaxes several times, sometimes for several hours, until the membrane is broken. The c i l i a and velar flaps are pushed out first, after the capsule is broken; and the hatching process is then completed within thirty minutes. The egg capsule is left to disintegrate as the animal swims away. The veligers are 100 to 175 microns in length and contain no pigment spots. They can be identified by their size and by six to ten characteristic, somewhat parallel ridges on the shell. They develop a red pigment spot on the proximal portion of each velar flap a fte r two weeks. The v elig ers swim for two weeks a f te r hatching, Table 10. Development of Cratena kaoruae at 256C. stage time first polar body 60 minutes after laying second polar body 70 to 1 1 0 minutes first cleavage 1 00 to 1 2 0 minutes second cleavage 170 minutes third cleavage 2 0 0 minutes blastula 9 hours trochophorc 24 hours shell appearance 36 hours veliger 4B hours Hatching 3 - 4 days 93 94 feeding on small diatoms. S e ttlin g and tnetamorphosia was not observed in the laboratory. Remarks. I propose that the species Cratena pilata should remain divided into two species; C. pilata and C, kaoruae. on the basis of the following observations and comparisons. Cratena p ila ta was described by A. A. Could in 1870 as A eolis p i l a t a . I t was reported from Massachusetts to North Carolina by various authors (Johnson 1934, Kepner 1943, Franz 1970 and Abbott 1974) . The animal was re-described by Franz (1968) who gave an Internal anatomical description but left the external to a simple "Other aspects of the external appearance and color are described by Gould (1870) and Moore (1964)." The animal studied In the Chesapeake Bay fits Franz’s (1968) description of the internal anatomy and radula, also verified by Franz (personal communication). The Cratena pilata collected from the Eastern Shore (Seaside) of Virginia fits Gould's d escrip tio n of the external appearance of Cratena p ilata. However, the external structures and appearance differ from the animal also called Cratena pilata found in Chesapeake Bay. Marcus (1957) described Cratena kaoruae from Brazil and north to North Carolina. It was later compared to Franz’s Cratena pilata, and the two species were considered to be the same (Marcus 1972). I believe that Kepner (1943) also worked with kaoruae. This species differs externally from Gould’s (1870) Cratena (Table 11) by general shape and color. The carmine s trip e o u tlin ed in s ilv e ry dots found on the dorsum of C . pilata (Gould's Cratena) is very striking and noticeable even in the smallest animals. The russet 3 tripe of kaoruae (Marcus’ Cratena) is usually noticeable, but at times is almost invisible. This color becomes bright when the Table 11. Comparison of characters of Cratena pilata and Cratena kaoruae. 3 H 3 Tt u ft u 2 ti o ft ti y 0 m p 11 » 10 i—4 X X i-f T3 X ) i t t A 4-1 4-1 ft t ftft ft x X X T3 1-4 X TI ft 41 O w CD c in o e u nt Tj i-l to n 9 < H ft > ■H -H ■9 ■H t - UP U 4-ift -U 4-1 t iJ i-4 ft 4) o J4—1 JJ O ft J fl 4J U ft 01 ftO ft i-l "H (0 >1 O O 11 ti » 91 41 -H M X C H U IH O u m (A 3 t f u >* u 0 til S q> 0} QJ t a > ti 3 41 * ft rt 3 O - X Ift > I-l CL o g ti H U3 ; a » ~a j ■—1 p ■ft 4-1 - 3 f 3i-i 3 [ 11 [6 O « & a o p p Oi j q m « m m rH i t O * -rt -1 x 1 > iTd J T "ti £ 1-1 4 t f ti ft V) (0 01 (0 o 3 (0 □ J h 01 . ft o X H ■H l i t S J ■ft ft t f o 0 (J i t 1> 3 O > t f » 3 nt t 3 4 O tiJ U-4 o O tu ■ l l X X 5 ft " ■ft X H X "ft t f t f ft o O t f u O ft i t U t f i t □ ti B CP QJ ft M CP 3 o (A D 3 S f o t o n o o r cr* 4-1 o to ti 0 □ >> ft nj c SO O O O I 1 ) H tiiH t f i 44-1 (A t f 3 to ) a t f J ( 4-1 qj 0 w W a) QJ o41 to to O cr* U X *H3 >+-i in 3 CP animal is preserved in alcohol and then fades In a few days. Could (1870) did not give a description of the Internal characters of his Cratena pilata. I found differences in the radula and jaws. The Jaws are similar In shape in both cases, but the color of pilata Jaws Is from pale yellow to clear, while kaoruae jaws range from yellow to brown. Radular teeth of kaoruae possess 4-7 cusps around a much larger central cusp, hut lack bifurcate cusps. ,£* pilata radular teeth may have 4-8 cusps around the central cusp. The leaser cuspa are frequently bifurcate. The odontopliore of pilata is wider, causing the attachment projections of the radular teeth to be spread further apart than those of C_. kaoruae. The egg masses of the two subspecies are superficially similar, but the arrangement of the eggs within the masses is different (Table 12, Plate 18). The courtship is more elaborate in kaoruae■ pilata was collected in this study only from the seaside of the Eastern Shore in salinities from 30 to 32 o/oo, while C_, kaoruae was found in Chesapeake Bay in salinities of 9 to 21 o/oo and occasionally at higher salinities of 28 to 30 o/oo on the seaside of the Eastern Shore. Family Glaucidae Glaucus atlanticus Forster 1777 (P late 14, Figure 7) Adult silvery white or yellow on the dorsal surface and light-blue, with dark-blue and white stripes on the ventral surface, Cerata clumped on peduncles (three peduncles on each side) and vivid blue. Adult up to 50 mm long. a tla n tlc u a was not co llected in th is study but has been reported at Virginia Beach, Virginia. Five individuals were washed 98 ashore along with the e l phonophores Velella and Porpita. It la one of the few peLagic nudibranchs. Abbott (1974) notes that they swallow air for bouyancy. G* atlantlcua is circumtropical {Abbott 1974) occasionally washing onto Virginia beaches in late summer. Remarks. Because these animals flo a t upside down on the surface of the water, most Illustrations and photographs taken of them (with stripes) are of the underside. The foot and Its outlines appear as stripes. The dorsal surface is plain. DISCUSSION Zoogeography. Even though several stations In the Chesapeake Bay and on the Eastern Shore bays were sampled intensively, there is little doubt that additional species of shell-less opisthobranchs occur in this area. However, diversity appears to be lower here than in New England and regions further south (Clark 1975, Calder 1968), The study area is low-lying and composed of salt marshes, mud flats and unstable bottoms. Except for shells and artificial pilings, jetties and bulkheads, there are no hard substrates. There is a wide range of temperature from 0°C to 30°C and a salinity range from homoiohaline to poikilohaline. New England is characterized by its rocky coast line which provides considerable area for attachment of organisms such as algae, sponges, bryozoans and cnidarians. Tropical areas have coral reefs that provide hard substrates. Diversity in shell- less opisthobranchs depends on temperature, salinity, substratum and food. Salinity In Chesapeake Bay restricts nudibranchs to those waters above 5- 7 ^ 0 0 . Within the salinity limits, species presence depends on bottom type and food. The opisthobranchs I studied are mainly benthit as is their food. Most of the prey species are found on shells, pilings and other hard substrata, although some attach to softer substrata such Zostera, Ruppia and various algae. Adequate substrata for prey species is essential for opisthobranch survival because the larvae will not settle and metotnorphose unless the living adult food is present (Thompson 1958), I observed on many occasions 99 100 similar areas only meters apartt in which one contained many opisthobranchs and the other none. The area with the opisthobranchs sometimes contained shells, an eel grass bed or other suitable sub strata. Because the animals are predominantly prey specific, it is even more important that the proper substratum is available to the prey. The 21 species of shell-less opisthobranch fauna of this area may be considered impoverished in terms of numbers of species, as compared with 37 noted by Franz (1970) from New England, 47 by Marcus and Marcus (1966) from tropical areas and 6 6 by McFarland (1966) from the west coast. Franz (1976) states that the fauna of eastern North America is minimally diverse relative to the northeast Atlantic. He notes this may be due to the unstable environment. A major reason for low d iv e rsity could be the geomorphology of the coast lin e. A considerable amount of work on western North Atlantic opistho branch zoogeography has been done by Franz and his students (Franz 1970, 1975; Meyer 1971, Clark 1975). New England opisthobranchs are predominantly amphi-Atlantic (Franz 1970), The percentage of amphi- A tlantic nudibranchs ranges from 78.5% in northern New England and Nova Scotia to 33% in the Chesapeake Bay area. This does not include Glaucus atlanticus, a circumtropical pelagic animal which does not f i t Ekman's (1953) defin itio n of amphi-Atlantic. There is a to ta l of 27% amphi-Atlantic opisthobranchs in the study area, with 21.7% amphiboreal and 4.3% (1 species) discontinuous amphi-Atlantic. The other 73% is restricted to the Western Atlantic. Marcus (1961) suggests that because the Atlantic was once narrower than at present the larvae of discontinuous amphi-Atlantic opisthobranchs, such as Doris verrucosa, were more able to migrate from one coast to the other. Placida dendritlca is a sacoglossan with a Tethyian distribution (Marcus 1961). This anim al’s rela tiv e ly long la rv a l lif e f a c ilita te s a vide distribution. A veil known classification of Western Atlantic zoogeographical provinces is that of Stephenson and Stephenson (1954). They included these provinces in their scheme: Arctic - limit north of Labrador; subarctic or Styrensian - Labrador to Gulf of St. Lawrence; Acadian - subarctic to Cape Cod{ Carolinian - Cape Hatteras to Cape Canaveral, The so called Virginian province, from Cape Cod to Cape Hatteras, was considered by them to be a transition zone between the Acadian and Carolinian provinces. Briggs (1974) divides the Western North Atlantic into four provinces: A rctic—to Gulf of St. Lawrence Western Atlantic Boreal— from Gulf of St. Lawrence to Cape Hatteras (cold temperate) Carolina—Cape Hatteras to Cape Romano, Florida (warm temperate) Caribbean—Florida south (tropic) The area from Cape Cod to Cape Hatteras, the 'Virginian' province is considered merely the southern portion of the cold temperate fauna. Cape Hatteras Is a break point specifically because of the Gulf Stream. The Gulf Stream flows northeasterly along the Atlantic coast line to Cape Hatteras where it veers off shore in a more easterly direction, Briggs (1974) states that the most important zoogeographic function of the Gulf Stream is to form an e ffe c tiv e b arrier between a cold-water area to the north and the warm water of the Sargasso Sea on the southeast. The cold, low -salinity water formed off New England 102 flows southwards along the Atlantic coast to Cape Hatteras {Beardsley, Boicourt and Hansen 1976), This cold current Influences the fauna and also seems to provide the means for larval forms of northern opistho- branchs such as Doto corortata to be carried into more southern w aters. Comparisons of opisthobranchs from the study area to other areas on the Western Atlantic reinforce Briggs' (1974) statement that the mid-Atlantic region Is only an extension of the Western Atlantic Boreal Province! although there is some overlap of species (Table 13)■ The months of collection of the species found on both sides of the Eastern Shore covered a period of 19 months (Table 14). Months with the greatest number of species present are September, November, December and January, The similarity of shallow water opisthobranch fauna between northern and southern waters decreases northward, Marcus (1961) found 72K of the opisthobranchs in Miami and 62% of the opisthobranchs in Beaufort, North Carolina and in southern middle Brazil, In the Chesapeake Bay region, this affinity has decreased to 35%, indicating a break point at Cape Hatteras. Phenology. Of the opistobranchs found in this study, 10 are herbivorous (aplysiids and sacoglossans) and 13 are carnivorous (nudibranchs). Two of the carnivores, Boris verrucosa and Doriopallla pharpa, feed on sponges; four eat on bryozoans, five consume hydroids and scyphozoans and one, Glaucus atLanticus, feeds on pelagic sip- honophores. Animals with a Stable food supply, such as I), pharpa, are present and abundant all year. Those that are able to change their food seasonally are also present all year (Doridella obscura) . Other animals having unstable food supplies or limited temperature tolerances may move to deeper water (out of the collection scope Table 1 3 . List of Opisthobranchs from Chesapeake Bay and V irg in ia’s Eastern Shore W. Atlantic Boreal Amphi- Acadian Virginian Carolinian Species Atlantic province province provinc Aplysla villcoxi + + Phyllaplvsia engeli + Elysia chlorotlca + + -V Elvsia catulus + + + Henna e a cruciate + + Placida dendritica + + Ercolania vanellus + + Ercolanla sp. + Stlllger fascatus + + A lderla modesta + + + Doris verrucosa + + + + Polvcerella emertonl + Acanthodorfs pilosa + + + + Okenla cupella + Doridella obscura + + + Dorlopsilla pharpa + + -f Doto coronata + + + + Tenellia adspersus + + + + Tenellia fuscata + Tenellia sp. + Cratena pilata + + Cratena kaoruae + Glaucus atlanticus + + 103 104 of this study) or die. The population would then need to be re cruited from unknown substrate habitats and repopulated each season. Populations of prey-specific species (Elysia catulus, Dorlopgilla pharpa and others) can be decimated if a disaster removes the food species. Tropical Storm Agnes In 1972 did much damage to the Zostera community in Chesapeake Bay (Orth 1976). As a consequence, Elysia catulus has disappeared. This species apparently has poor recruitment and has not repopulated the Bay, even in areas of Zoatera regrowth. In New England, Clark (1975) reports E. catulus spawning In June and July and then disappearing until late August. It has only one spawning season a year. Little else is known about its habits. Doriopsilla pharpa is another prey-specific opisthobranch having only one spawning period a year. If the sponge food of EL pharpa disappears, the nudlbranch soon follows. Recruitment would be slow, if at all, because of the Type 3 development of I). pharpa. Probably the best way of reintroduction of such a species would be through Introduction of prey sponges. Chesapeake Bay is the southern limit for 29% of the species in the study area ( 6 species) and the northern limit for 4.33! of the species (1 species). Three species have been found only in the Chesapeake Bay, probably because they have not yet been discovered elsewhere- It is unlikely that any species are restricted to the Chesapeake Bay area, due to considerations discussed previously. Until recently, many studies of opisthobranchs did not include data on seasonal distribution of the animals. A considerable number of species lists were based on one or two samples. More recently however, studies Included phenology and have given detailed opisthobranch 105 life cycles and seasonal abundance (Clark 1975, Nybakken 1974, Miller 196Z). These studies require sampling various stations periodically for at le a s t one year. Observations from Wachapreague included year-round sampling, while earlier observations at the Chesapeake Biological laboratory were made in all but the coldest months—December to March* However recent experience has confirmed that year-round sampling is essential to collecting and understanding opisthobranchs in this area* The most species were collected in the months of November, December, January and September (Table 14). Some of the animals are present at other times of the year, as well as the winter months. Inclusion of additional collection data does not appreciably change the numbers of species found each month (Tables 15 and lb ). Clark (1975) found that most of the nudlbranchiate (shell-less opisthobranchs excluding aplysiomorphs) species in Connecticut waters have peak reproductive activity and population size tn late spring and early summer. Because of a lag time of several months between disappearance of adults and appearance of Juveniles, he concludes that nudibranchiate species which metamorphose and settle in Connecticut are spawned elsewhere (Clark 1975) . The same type of situ a tio n may be present in Chesapeake Bay and seaside Eastern Shore, with larvae of some species, such as Placlda dendritica and Doto coronata, orig inating further north. Shell-less opisthobranchs are comprised of two general groups—those with sub-annual life cycles feed, mature and re produce rapidly on transient prey, while those with annual or longer life cycles feed, mature and reproduce annually on relatively Table 14. Months of collection at stations on Eastern Shore {bay and seaside) Oi r-' 1 cn r- m z u > 07 o ft ft m O W) ■“1 ft Eft S3 $ S5 a ft o > 01 s ft CJ 0 (A 0 07 0 id Ui 0 c u § ) } ) t f ft X ft x x x t f ■H tu ft pH Cl 01 t f U ?■ n dftT3ftft f CL t f 3 T t f id cd ■ > > ft V X tx] ft H ft ft to 3 3 ft ■H o ■ t f a • t f ft t f pH ft X X X x x x X X X X X X X x x x X X X P t f i o t f U t f g t f h — t f ■—1 t f t f ] t f H X X XXX XXX X X X X X X x X td > O t f t f O ft t f ft 4 4 n i ■ft ■ft t f X X X X u ft t f t f 41 i a t f u Of O ft DO u a) a ■ft X X XXX XXX XX X t f t f ■ft t f > ft cd ft t f Ifl Table 15. Seasonality of some opisthobranchs in Chesapeake Bay and Virginia ID Eastern Shore. 107 108 a> Vi 0 1 u ' i ! p u & 41 U a s > (0 W 55 c y (to y u Ok <4 u 'H o VJ P o -H VJ C 00 h 6 Ifi "H OJ m 41 > VJ I y mo Vi ED a. n) B $ Efl < 00 00 I 4Q 40 S' OJ It FCl D 41 (4 01 a) e I &. p (4 ■n (0 at * rd u I p *H H a (fl < JS a c n (4 eg U X U XI ■H ■yP <5c TJ Xi at t i D OJ on □ C y 3 a stable p*ey populations. The first type is called opportunistic (MacArthur 1960, Nybakken 1974) or e x p lo itis t (Clark 1975) and the second, equlibrium (MacArthur 1960, Nybakken 1974) or s tra te g is t (Clark 1975). Most of the smaller species, especially eollds, fall Into the opportunistic group. They appear almost as soon as their food is present, mature, and sometimes reproduce more than one generation in a matter of weeks before the food species Is consumed or dies, whereupon the opisthobranchs die. The mode of dispersal is by free-swimming larvae. The necessity of having the living adult prey present as an induction for metamorphosis (Thompson 1958) pre vents the animals from settling on barren areas and starving. Most of these animals exhibit Type 1 or Type 2 development (Table 3), Equilibrium species are generally larger and more stable in abundance. They feed on prey present year-round and have a long maturing period. Doriopsilla pharpa is such a species, having development Type 3 and found continuously on its sponge food, except immediately after spawning. At this time the adults die and the young have not been seen. The equilibrium species also metamorphose and settle in the presence of living adult prey, but do not seem to rocolonize areas as quickly as the opportunistic species, possibly because of a shorter, or non-existent, free-swimming larval stage. Study of reproduction and early development is also affected by the group of species collected. Opportunistic species almost always spawn when brought into the laboratory, since they mature at a relatively small size and age, while equilibrium species may be collected at times other than their specific spawning periods. They can remain alive and healthy in the laboratory for many months before they spawn. 1 1 0 Students of opisthobranchs have long pondered the questions: Where do sudden populations come from? where do they disappear to? and in what form do they overwinter nr exist when they are not apparent? The subject of migration in nudlbranchiate (shell-less) opisthobranchs has been discussed by many authors (Crozler 1917, M iller 1962, Nybbaken 1974 and others). The sudden population ex plosions of breeding or non-breeding individuals led to Crozier’s (1917) theory of migration of adult opisthobranchs to shallow waters from deeper waters. More collecting has Indicated, except in rare cases, that population increases are not due to migration of adults eith er on/or offshore. M iller (1961) states that the abundance of a particular nudibranch species in a particular habitat is dependent on the amount of food available, This is true of the animals collected in my study as well. The presence, as well as abundance, of prey determined the prosperity of most species. My studies, and the literature, Indicate that the major factor of seasonality of nudi- branchiate molluscs depends on food. The sudden population blooms of opportunistic, nudlbranchiate molluscs follow closely blooms in th e ir food and are generally the result of recruitment of larvae from other areas. Occasionally a few adults will remain in the area to spawn. Cratena kaoruae was occasionally found in winter near Solomons, Maryland. At one time three small individuals were brought to room temperature in January (from 4°C to 22°C) and fed as much as they would eat. The individuals contained no visible ova when they were collected. One animal grew from 6.4 nun to 21.0 mm in 3 weeks, at which time ova were visible in the abdominal area. Mating took place soon after. I ll Other specimens kept In flouring water aquaria at ambient sea water temperatures disappeared when the temperature fell below 4“C and re-appeared when the temperature reached 11“C. I believe they burrowed Into the substratum or were covered by s i l t , a theory supported by the occasional presence of C, kaoruae in benthlc grab samples from Hampton Roads, Virginia. {M. L. Hass personal comm.) Other nudlbranchiate molluscs occasionally appear in grab samples, indicating that a t least a few individuals burrow. (3. kaoruae overwintering as adults feed and mature rapidly, reproducing 2 or 3 weeks a fte r appearance, In this area, opportunistic nudlbranchiate molluscs utilize several methods to successfully carry over periods of low abundance or absence of food species. They are: 1) burrowing Into the sub stratum of immature adults, 2 ) dying off of all but a few individuals that remain semi-active, 3) ab ility to begin breeding as soon as conditions change., and 4) recruitment from other sources by larvae. It is possible for adults and larvae to grow, mature and reproduce rapidly in the presence of abundant food and for the larvae to spend a much longer time in the plankton when the food is scarce. The equilibrium species studied overwinter in a non-breeding adult stage were less active than during Che rest of the year. Absence of these animals a fte r breeding could be due to death of adults. Some of the equilibrium species found In the study area were not found year-round. This could be attributed partly to collection techniques, or to these animals burrowing in the bottom when their food ia inaccessible. LITERATURE CITED Abbott, R. I, 1974. American S eashells. Van Nostrand Reinhold Co., New York. G63 pp, Agassiz, L. 1850. Notes in minutes of Nov. 7, 1849 meeting of Boston Soc. Nat. Hist, Proc. Boat. Soc, Nat. Hist. 3:191. Alder, J. and A. Hancock. 1843, Notice of a B ritis h species of Calllopaea D’Orbigny, and four new species of Eolis. with observations on the development and structure of the nudi- branchiate mollusca. Ann, and Hag. Nat. Hist, 12:233-238, Alder, J. and A. Hancock. 1845-1855. Monograph of British nudlbranchiate mollusca. Ray Soc., London. Fts. 1-7 438 p. 84 pis. Baba, K. 1937a. Opiathobranchia of Japan I. J. Dept. Agric. Kyushu Univ. 5(4):195-236. Baba, K. 1937b. Dpisthobranchla of Japan II, J. Dept. Agric. Kyushu Univ. 5(7):289-344, Baba, K. and I. Hamatani. 1952. Observations on the spawning habita □f some of the Japanese Opisthobranchia, Publ. Seto. Mar. Biol. Lab. 2:87-90. Baba, K. and I. Hamatani. 1963. A short account of the species, Tenellia pallida (A and H) , taken from Mukaishima, Japan (Nudlbranchia-Eolldoldea). Publ. Seto Mar. Biol. Lab. 11:337-33B, Bailey, K, and J. S. Bleakney. 1967. First Canadian report of the sacoglossan Elysia chlorotlca Gould. Veliger 9:353-354, Beardsley, R. C., W. C. Boicourt and D. V. Hansen. 1976. Physical oceanography of the Middle Atlantic Bight. Am. Soc. Limnol. Oceanogr. Spec. Symp. 2:20—34, Bleakney, J. S. and K, Bailey. 1967. Rediscovery of the salt marsh sacoglossan Alderia modesta Loven in Eastern Canada. Proc. Malac. Soc. Lond. 37:347-349. Bookhout, C. G. 1953. Check l i s t of marine invertebrates a t Beaufort, N. C. Duke University Marine Laboratory. Briggs, J. C, 1974, Marine zoogeography. McGraw-Hill, New York, 475 pp. 1 1 2 Calder, D. R. 1968. Hydrozoa of southern Chesapeake Bay. Ph.D. Dissertation, College of William and Mary, Williamsburg, Va. 158 pp. Cargo, D . G. and L. P. Schultz. 1967. Further observations on the biology of the sea nettle and Jellyfishes in Chesapeake Bay. Ches. Sci. 8:209-220. Clark, K. B, 1975. Nudibranch l i f e cycles in the Northwest A tlantic and their relationship to the ecology of fouling communities. Helgol, Wiss. Meeresuntere. 27:28-69. Clark, K. B. and D. R. Franz. L9G9. Occurrence of the sacoglossan opisthobranch Hennaea dendrltica Alder and Hancock in New England. Veliger 12:174-175. Cory, R. L. 1967. Eplfauna of the Patuxent River estuary, Maryland for 1963 and 1964. Ches. Sci, 8:71-89. Crozier, W. J. 1917. On the periodic shoreward migration of tropical nudibranchs. Amer, Nat. 51:377-382, Cucagna, A. Z. and J . Nusbaum. 1915. Fragmente iiber re s titu tio n bel den nudibauchiern. (Hermaea dendritica Alder et Hancock)- Arch. Entw. Mech. Leipzig. 41:558-578. De Kay, .T. E. 1843. Natural history of New York, Part V. Mollusca. D. Appleton and Co., New York. 271 pp. Ekman, S, 1953. Zoogeography of the sea. Sidgwlck and Jackson, Ltd., London. 417 pp. E lio t, C. , N. E. 1910. British nudlbranchiate moHusks, Supplement. IN Alder and Hancock Mon. B rit. 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(abstract). Franz, D, R. and K. B. CLark. 1972. A discussion of the system atica, reproductive biology, and zoogeography of Polvcerella emertoni and related species (Gastropoda: Nudlbranchla}. Veliger, 14:265-268. Carlo, E, V, 1977. Opisthobranchs found off Little Egg Inlet, New Jersey, with notes on three species new to the state. Nautilus. 91:23-27, Gosner, K. L. 1971. Guide to id e n tific a tio n of marine and estu arin e Invertebrates. John Wiley 6 Sons, Inc., New York. 693 pp. Gould, A. A. 1841. Report on the in v erteb rate of M assachusetts. Cambridge 373 pp. Gould, A. A. 1870. Report on the Invertebrate of Massachusetts, 2nd ed. W, G. Blnney Ed. Wright and P o tte r, Boston. 524 pp. 12 col pis. Graham, A, 1955. Kolluacan d iets, P t o c . Malac, Soc, London. 31:144-159. Green, R. W. 1968. The egg masses and veligers of Southern California sacoglossan opisthobranchs. Veliger, 11:100-104, Green, R. W. 1970. 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Amer. Zool. 9:604, (Abatr.) Vogel, R M, 1971. The biology and a redoscription of the opisthobranch mollusc Hermaea cruclata Gould, from Chesapeake Bay. Veliger. 14:155-157. Vogel, R M. and L. p. Schultz. 1970. Cargoa c u p e lla , new genus and new species of nudibranch from Chesapeake Bay and the generic status of Okenia Henke, Idalia Leuckatt, and Idalla firs ted. Veliger. 12:388-393. Wass, M. L, (Ed.). 1972. A check list of the biota of lower Chesapeake Bay. Va. In at. Mar. S ci. Spec. Sci. Report No. 65. 290 pp. Williams, G. C. and T, M. Gosliner, 1973. A new species of anaspidean opisthobranch from the Gulf of California (Mollusca: Gastropoda). Veliger. 16:216-232. 121 APPENDIX Collection Stations for Opisthobranchs Maryland Stations Bloody Point Knapps Narrows Herring Bay Choptank River Little Choptank River C . B . L . pier, Solomons, Maryland S t . John Creek St. Leonard Creek Bruotne Island Queen Tree Landing Hallowing Point St. Mary’s College pier, St. Marys, Maryland Hooper Straits Beacon Deal island Manokin River Broad Creek Virginia Stations Gloucester Point Davis Wharf Methodist Camp Craddock Creek Hacks Neck Pungoteague Creek Finney’s Creek Onancock Creek Nassawaddox Creek Cherrystone Creek Saxis Island Fisherman’s Island Qecahannock Creek Wachapreague Channel, with stations at these markers Osprey Light 1 i gli t it h light tf 6 marker if 9 marker it 121 L i t t l e fo o l’s Creek marker if 125 marker if 128 Quinby Quinby Bridge Chincoteague Bay Wallops Island Swash Bay Wachapreague Figure 7. Collection sites of Aplysia w illcqxi, Phyilaplysia eng ell and Glauctia atlanticua in Virginia and Maryland. X ^ Apt/Sio mffcQid 0 P/ijtJfapfftfO tltff/i 1 Gtaucus atfa/it/cui •V* Figure 8. Collection 3ites of Elysia chlorotlca and Elys catulus In Virginia and Maryland. i 5 V ■ f /r i / o c M ty a f/c a A £ t y Figure 9. Collection s ite s of Hennaea cruciata and Placida dendrltica in V irginia and Maryland. 9 Ntrmaea cructOfQ A Pfotida titttffritfcf Figure 10* Collection sites of Ercolania vanellus, 5tiligcr fuacatua , Alderja modesta and Ercolania sp. in Chesapeake Day* A Ertotortio tp. B Aiaifit matftito — £rcoV*t Acanthodoris pilosa and Doria verrucosa in V irginia and Maryland. ■ Potjtenlta tmtrtcm A O&rts ktfftfCQtQ 0 Acof>tRodorti etteto Figute 12 Collection sites of Do to coronata and Oketi ia cupella in Virginia and Maryland. ■ Doto CO/pngfo A tvptlfa Figure 13. Collection sites of Doridella obacura and Dorlopsllla pharpa In Virginia and Maryland. ■ Odrtdtiffo QbsCusa A DOr/CfiHtfa pfiarptr * Figure 14, Collection sites of Tenellla adaperaa, Tenellla fuscata and Tenellla sp. In Virginia and Maryland. 3 X p # Tttwtiia ip- * trfiptfto T H t* i l i a fv% ca!o Figure 15. Collection sites of Cratena pllata and Cratena kaoruae in Virginia and Maryland- 9 Crattfla pifatp figureFigur~ 16*16. TypicalTypical surfacesurface salinitysalinity pattern pattern In in tiie the Chesapeake Chesapeake Bay andand tributarytributary estuariesestuaries fromfrom Pritchard Pritchard 1952i 1952, P la te 1 Figure A- Dorsal view of generalized dorid nudibranch B. Lateral view of generalized dorid nudibranch MANTLE LEAVES ON RHIN0PH0RE5 PIT GILLS A. RHINOPHORES PAPILLAE GILLS FOOT PALLIAL RIDGE B. Plate 2 F ig u r e C. Dorsal view of generalized colid nudibranch D. Lateral view of generalized ealld nudibranch ANTERIOR ANGLE ORAL OF TOOT TENTACLE EVE SPOT CERATA TAIL HEART RH1NOPHORE - ORAL TENTACLE FOOT TAIL g e n it a l OPENINGS B. Plate 3 Figure A. Aplysla willcoxi, lateral view B . Aplysia willcoxi, dorsal view C. Phyllaplyala engeli, dorsal view D. Phyllaplysia enfjell, lateral view UlMilbiMlUUdkt Plate 4 Figu re A. Elyaia chlorotica, dorsal view, paropodla closed B. Elyala ch lo ro tica. egg mass C. Elysla chlorotica. dorsal viewt parapodia spread D. Elys la chlorotica. lateral view ' Vin ' w m m Plate 5 Figure A* ErcoLanja ap,, doraat view B. Ercolaula ap., ceras C. Ercolania sp., ventral view D* Elyala catulus» dorsal view E. Elysia calulua, lateral view Heart B. o O o o Plate 6 Figure A. Stiliger fuacatus, dorsal view B. S tlH g er fuscatus, egg mass C. Ercolania vanellus. dorsal view D. Ercolaaia v anellus, egg mass A. c. n Plate 7 Figure A. Ilerniacfl c ru c la ta , dorsal view B. Herraaea cruclata, three-quarter C. Hermaea cruclata. egg mass Plate 8 Figure A* Placida dendrltlca, dorsal view B. Placida dendrltlca, ceras C. Placida dendrltlca, egg mass D. Placida dendrltlca, lateral view C«rciB P late 9 Figure A. Alderla modesta, doreal view B. Alderla modesta. egg mass C. Alderla modesta, lateral view ^ .Pi UsA-; P late Figure A* Parts verrucosa, la te ra l view B. Doris verrucosa, egg mass C. Paris verrucosa, dorsal view P. Comparison of papillae a■ Ports verrucosa b. Acanthodoris pilosa E. Comparison of rhirtophore& a, Doris verrucosa b. Acanthodoris pilosa muthroom •hoped conical •hoped Papilto* Plate 11 Figure A. Folycerella enter ton I, dorsal view B. Folycerella emertonl, ventral view C. Folycerella emertonl, lateral view D. Folycerella emertonl, egg mass A. B. n Plate 12 Figure A* Acanthodoris p ilo s a , la te ra l view B* Acanthodoris pilosa, egg mass C. Acanthodoris p ilo s a , dorsal view D. D oridella obscura, la te ra l view E. D oridella obscura, egg masa F. Doridella obscura, dorsal view A A/OOj <-r V u r f't -»\ <’<'--** l ^T2VV> ..M HHiiiHffU.'.'l^S Plate 13 Figure A* Okenia cupella, daraal view B. Okenia cupalla, egg mass C. Oketila cupella, lateral view A. Plate Figure A* PoriopBilla pharpa, dorsal view B. Dorlopsllla pharpa, egg mass C. Porlopsllla pharpa, lateral view D. Glaucug atlantlcus, dorsal view E. Glaucua atlanticus, ventral view .... , ;p\ ' . . 'I ' I I I ' ' ·..• ~/ A. Plate 15 Figure A. Doto coronata, la te r a l view B. Doto coronata, dorsal view c. Doto coronata, rhinophore D. Do to coronata, ceras E. Doto coronata, egg mass Rhinophore CdfQ* Plate 16 Figure A, Tenellia adapersa. dorsal view B, Tenellia adsperaa, ventral view C, T enellia adaperaa, egg mass D, Tenellia fuacata, dorsal view E, Radular teeth a♦ Tenellia adapersa b* Tenellia ap. Tenellia adapersa, lateral view Rodular Teefh T o n eIsa ! a d s p n r s a E. Plate Tenellia ap., dorsal view Tenellia sp*. ventral view Tenellia sp.t lateral view Tenellia sp.t egg mass c. Plate 19 Figure A. Crateaa kaoruaetventral view B . Cratena kaoruae lateral view C, Cratena kaoruae egg mass D, Cratena kaoruae dorsal view showing arrangement of cerata and color - i ^ J! >, L. ; , .■ Plate 19 Figure A. Cratena pllata, lateral view B. Cratena p ll a ta , close up of egg mass showing arrangement of egg capsules C. Cratena pllata, dorsal view showing cerata arrangement and color pattern D. Cratena p lla ta , egg mass White ■A' Plate 20 Figure A, Placida d en d rltlcat larva showing s h e ll growth Velum Growth line r 1 L|mm Plate 21 Developmental stages of Poriopsilla pharpa Figure A. 1-cell and 8-cell stage B. 4-cell stage C. veliger with shell D. late veliger Volar cilia Egg capsule Velum Foot Mantle Shell Visceral mate and yolk Rhinophore rudiment Eye Egg capsule I "*H ,lm m Plate 22 Developmental stages of Dariopsilla pharpa Figure A and B. undergoing metamorphosis and losing its shell C. larval shell Man Ho Rhinophora rudiment Yolk Foot A 5k oil .1 mm Mantle Eyo Point of attachm ent to shell .1 mm Plate 21 Juvenile Doriopsllla pharpa Figure A. day-old juvenile B. week-old Juvenile C. week-old juvenile -— Anterior mantle lobe* A. Posterior mantle lobes Manlle Head Gland cell* B. Spicule* Body fa* \Q r Anal position Waste la c Rhlnophores Eye Mantle Spicules Waste sac Plate 24 Figure A* spicules of Dorlope Ilia pharpa 10X B. spicules of Dorlopsllla pharpa 43X C. spicules of Dorlopsllla pharpa 10X Dt spicules of Cljone celata 10X .. ., A. t. B. ~~j/ .... lOX 43X c. - 10)( D. IO)( Plate 25 Figure A* spicules of Doris verrucosa 10X B. spicules of Prosuberites epiphytmm (encrusting sponge) 43X C. spicules of Okenia cupella 10X A. rox Plate 26 Developmental stages of Tenellla sp. Figure A. egg tnass 11. early veligers C. pre-hatching veliger D. veliger, 3 days after hatching Vi&caro Visceral mass Larval retractor muacle VITA Rosalie Marie Vogel Horn in Delhi, New York, on 6 June 1943. Graduated from New Bern High School, Neiw Bern, North Carolina, 1961. B. S. in Biology frotu East Carolina College, Greenville, North Carolina, 1965, M. A. in Biology from East Carolina College, 1967- Teaching Fellow at Eaat Carolina College, 1965 to 19 67- Faculty Research Assistant in sea nettle program at Chesapeake Biological Laboratory, Salomons, Maryland, 1967 to 1971. Attended The George Washington University (n ig h ts), 1969 to 1971- Employed in Division of Mollusks, Smithsonian I n s titu tio n , Washington, D. C-, 1971 to 1972, Entered the School of Marine Science of the College of William and Mary, Williamsburg, Virginia, June 1972- Graduate Assistantship in the Invertebrate Ecology Department, September, 1972. 159