Caprella Drepanochir Class: Malacostraca Order: Amphipoda, Caprellidea a Skeleton Shrimp, Or Caprellid Amphipod Family: Caprellidae

Home , Aeginina, Aeginina longicornis, Caprella, Caprella californica, Caprella equilibra, Caprella mutica

Phylum: Arthropoda, Crustacea Caprella drepanochir Class: Malacostraca Order: Amphipoda, Caprellidea A skeleton shrimp, or caprellid amphipod Family: Caprellidae

Taxonomy: The Caprellidae are a very rather than laterally compressed (compare to distinctive family of amphipods. They were gammarid amphipods, e.g. Eogammarus previously a separate amphipod suborder, but confervicolus) (Kozloff 1993; Watling and were recently found to be polyphyletic, arising Carlton 2007). at least twice from different gammarid Cephalon: Round cephalon with no dorsal amphipod lineages (Laubitz 1993; Takeychi spines or tubercles (Fig. 1) (Laubitz 1976), 1993; Watling and Carlton 2007). Current however body spination is a highly variable research places them as highly modified trait among individuals (Watling and Carlton members of the suborder Corophiidea (Myers 2007). Head partially fused with the first and Lowry 2003; Watling and Carlton 2007), a pereonite (segment of pereon) and the first taxon divided into two infraorders (Caprellida, pair of gnathopods (Fig. 1). Pereonite one not Corophiida) each with different evolutionary more than twice as long as head in male feeding strategies and associated morphology (Laubitz 1970) and shorter in female (Laubitz (Myers and Lowry 2003). 1970) (Fig. 2). Rostrum: Cephalon without rostrum Descripton (Laubitz 1976). Size: The illustrated specimens (from Coos Eyes: Small (Laubitz 1976) (Fig. 1). Bay) include a 13 mm long male (Fig. 1) and Antenna 1: Less than half total body an 8 mm long female (Fig. 2) (Measured from length (Laubitz 1970). In males, the first anterior (head) to posterior (abdomen), antenna is approximately equal to the Laubitz 1970). Males collected in Japan were cephalon combined with pereonite two 13 mm (Arimoto et al. 1976; Utinomi 1943) (Laubitz 1970) (Fig. 1). Articles 2–3 of while those from Alaska were 12.4 mm in peduncle are setose while the flagellum is length (Laubitz 1970). shorter than peduncular articles one and two, Color: White, with brown chromatophores. and bears 13 articles (Laubitz 1970) (Fig. 1). The illustrated female is darker than the male In the illustrated female, antenna one is a little specimen. longer than cephalon and pereonite one and General Morphology: The body of the flagellum has 10 articles (Fig. 2). amphipod crustaceans can be divided into Antenna 2: Antenna two in the three major regions. The cephalon (head) or illustrated specimens is longer than the cephalothorax includes antennules, antennae, peduncle of antenna one and has flagellum mandibles, maxillae and maxillipeds with short setae (Laubitz 1970) (Figs. 1, 2). (collectively the mouthparts). Posterior to Mouthparts: Mandible with molar the cephalon is the pereon (thorax) with (McCain 1975) and without palp (McCain seven pairs of pereopods attached to 1975). Left ‘lacinia mobilis' with five teeth (Fig. pereonites followed by the pleon (abdomen) 5) and right ‘lacinia mobilis' denticulate but not with six pairs of pleopods. The first three sets five-toothed (McCain 1975) (not figured). of pleopods are generally used for swimming, Pereon: Pereon with only six segments (not while the last three are simpler and surround seven as in other amphipods) and no the telson at the animal posterior. Caprellid pereopods on pereonites three or four amphipods differ from the rest of amphipoda (Caprellidae, McCain 1975; Laubitz 1976). in that the abdomen is greatly reduced, Pereonites cylindrical and longer than deep especially the last three abdominal segments (Laubitz 1976). Pereonites in this species are (urosome) and associated appendages without dorsal spines or tubercules, but are (uropods). Their body is also elongated covered with fine hairs (Fig. 1). Male

pereonite one is not more than twice the grasping spines (Fig. 1c). Female pereopods length of the head while female pereonite one more slender than those of males (Laubitz is shorter than the head (Laubitz 1970) (Fig. 1970) (Fig. 2). 2). Gills on pereonites three and four only. Pleon: The pleon or seventh pereonite is Round in shape and fleshy (Caprella, Mayer reduced and often unsegmented in caprellids 1890; Watling and Carlton 2007) (Figs.1, 2). (McCain 1975). Female individuals with one Gills in male individuals are more circular and pair of lobes, but no single-articled females are broadly rounded (Watling and appendages above these lobes (Figs. 2, 4) Carlton 2007). Oostegites (marsupium) (Caprella, McCain 1975). present on pereonites 3–4 in females only. Pleonites: The marsupium consists of two pairs of Urosomites: foliaceous plates called oostegites Epimera: (Caprellidae, Laubitz 1976) that grow from gill Telson: bases (Fig. 2) (Arimoto et al. 1976; Watling Sexual Dimorphism: Males much larger and and Carlton 2007). more elongate than females, with a longer Coxae: first pereonite and an exaggerated second Gnathopod 1: Male gnathopod one is gnathopod. Females when brooding have small and the propodus and dactyl have conspicuous oostegites (see pereon) and serrate grasping margins (Fig. 1) while the lack mandible palps (Watling and Carlton female gnathopod is small, setose (Fig. 2). 2007). Gnathopod 2: Male gnathopod two is very large, especially the propodus, width Possible Misidentifications being less than half overall length. The In contrast to the more familiar gnathopod is setose, except the dactyl and Gammaroidea, the bodies of caprellid distal part of propodus (Laubitz 1970). The amphipods are elongate and cylindrical, their basis is small, with no lateral spines at the pereonites are very long and their three pairs base (Figs. 1, 1b). The propodus is of pereopods are prehensile. Caprellids have tuberculate anterodistally and palm is with 2–3 pairs of gills on the middle pereonites and small proximal grasping-spine, large distal lack the abdominal pleopods of gammarid poison spine, large triangular projection distal amphipods. Members of three subfamilies to poison spine and separated by cleft. (family Caprellidae) occur locally including, There are no anterodorsal projections on Caprellinae, Paracercopinae and Phtisicinae. propodus in this species (Laubitz 1970) (Fig. The caprellid family Cyamidae are parasitic 1). The dactyl is heavy, slightly curved, with on cetacean mammals. They are very short inner margin slightly denticulate and not bodied, dorso-ventrally flattened (like setose. The gnathopod is attached just isopods), and have third and fourth pereonites posterior to middle of pereonite two (in male) especially adapted for hanging on to their and attached near the middle of pereonite host. two, but not at its anterior end (in female) Phtisicinae have three pairs of gills, not (Laubitz 1970) (Fig. 2). The palm of propodus two (unlike Caprellinae). In addition, they has a proximal grasping spine and an have no molar surface on the mandible. The accessory spine, and a minute distal poison Phtisicinae have rudimentary pereopods on spine (Fig. 3). Ventral spines between pereonites three and four (Laubitz 1970). Of insertions of second gnathopods are lacking this family, Perotripus brevis has been in this species (Fig. 1a). Female gnathopods reported from California (McCain 1975; are much smaller than those of males. Watling and Carlton 2007). It, as well as Pereopods 3 through 7: Pereopods Cercops compactus (Laubitz, 1970), occurs in 5–7 prehensile (for grasping) and increase in Puget Sound. Caprella compactus has also size posteriorly (Fig. 1). Propodus on all been reported from the outer coast of Oregon, pereopods rather stout, with a concave inner at Cape Arago (Laubitz 1970; Martin 1977) edge and a proximal tooth with a pair of and is in the only representative of the

Hiebert, T.C. 2015. Caprella drepanochir. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. subfamily Paracercopinae locally. Cercops have only a uni-articulate flagellum (McCain compactus does not have an elongate body 1975). as other caprellids do, its abdomen has five A few caprellids have a ventral spine segments, and pereonites five and six are between the insertions of the second short and stout (Watling and Carlton 2007). gnathopods (C. drepanochir does not): C. The subfamily Caprellinae is the most californica, C. equilibra, C. mendax, and C. speciose with 23 species in the genus pilidigitata (Laubitz 1970). Caprella Caprella, three in Tritella and one each in californica has a long, forward directed Deutella and Mayerella (Watling and Carlton cephalic spine (Laubitz 1970). Both the 2007). propodus and basis of the male gnathopod Tritella pereopods have only one article two are very long in this species. Caprella and their second antennae have swimming californica has a wide distribution from the setae (Laubitz 1970; McCain 1975). Three western to eastern Pacific coasts (Martin species are found in Oregon: T. laevis is 1977). Caprella equilibra has no cephalic strongly stenohaline, and is found offshore spine (McCain 1975) (like C. drepanochir). from British Columbia, Canada to Monterey But unlike the latter species, it has anterior Bay, California (Martin 1977). It has lateral projections on pereonite five, large anteriorly pointed body spines and short lateral spines at the base of the gnathopod spines on the stout flagellum of its second two (McCain 1975) (Fig. 1b), and the ventral antennae. This species can display spines between the gnathopods (Figs. 1, 1a). ''intersex" features (Laubitz 1970), making Northeast Pacific range of C. equilibra males and females difficult to distinguish. includes San Juan Islands, Washington and Tritella pilimana has laterally pointed body British Columbia, Canada (Martin 1977). spines and its second antennal setae are Caprella mendax has no cephalic spine, no long on a slender flagellum. It is more lateral projections on pereonite five, and only euryhaline than T. laevis and is found from small lateral spines at the bases of the Alaska to California (Martin 1977). Tritella second gnathopods. Its dactyl is not setose tenuissima is a deep water species, known and its distribution ranges from Vancouver off shore in southern California. It lacks Island, Canada to San Diego, California swimming setae on antenna two and (some (Martin 1977). Caprella pilidigitata has no believe) should be transferred to the genus lateral spine near the base of gnathopod two Triliropus (McCain 1975). and its dactyl is setose. The genus Metacaprella was One group of Caprella species has at characterized by a pair of appendages above least a slight cephalic spine (and lacks ventral the usual lobes on the female abdomen spines between the second gnathopods, (as (McCain 1975) where Caprella spp. have only above) and includes C. natalensis, C. the one pair of lobes (Fig. 4). Caprella penantis, C. brevisrostris, C. pustulata, C. anomala and C. kenneryli were formally simia and C. scaura. Caprella natalensis (=C. members of this genus (M. anomala and M. angusta and C. uniforma, Watling and Carlton kenneryli). Both have a small pair of sharp 2007) has a slight cephalic spine and small spines on the heads and are reported from dorsal pereonite spines, except on pereonite California and from Puget Sound, Washington one. Gnathopod two is attached at the (Keith 1971; McCain 1975; Martin 1977). anterior end of the second pereonite in males. The genus Caprella is characterized by The northeast Pacific distribution of C. the presence of gills on pereonites 3–4, natalensis includes British Columbia, Canada oostegites and mandibles without palps to Santa Cruz, California (Martin 1977). (females) (Watling and Cartlon 2007). Caprella penantis is morphologically similar to Caprella greenleyi has been reported living C. natalensis however pereonite five is on hydroids and algae and on the sea star usually longer than six and seven in the latter Henricia spp. both in Oregon and in species (see Laubitz 1972; Watling and California (McCain 1969, 1975; Martin 1977). Carlton 2007). Caprella brevirostris has only Unlike most free-living caprellids, it is quite a very slightly produced rostrum, not a stout, and has unusual antennae-- both pairs cephalic spine (Arimoto et al. 1976). It differs

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12700 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] chiefly from C. drepanochir in that it lacks propodus (on second gnathopod in males) is grasping spines on its pereopodal propodi as long as pereonite two (Keith 1971). Its (Fig. 1c). It has been reported from the first antennal peduncle is finely setose coasts of Japan (Arimoto et al. 1976), Korea (McCain 1975). It has a triangular cephalic and China (Martin 1977), and from California projection, directed anteriorly (McCain 1975), (McCain 1975), but not from Puget Sound which is lacking in C. drepanochir. C. incisa (Keith 1971) or from Oregon (Laubitz 1970). has been reported from British Columbia, Caprella pustulata (Laubitz 1970) has a Canada to southern California (Martin 1977). dorsal, upward directed knob on its head. Caprella mutica, an Asian species, has now The head and pereon are covered with large been reported from California (Martin 1977; and small tubercles (Keith 1971). The male is Marelli 1981), and was found in Coos Bay setose on the second gnathopods and on with C. drepanochir (authors). It has also much of the body. The antennae have some been called C. acanthogaster humboldtiensis very long setae. Caprella pustulata is (Martin 1977). Caprella mutica has dorsal reported from British Columbia, Puget Sound projections on pereonites 3–5, but not on the and from Oregon (Laubitz 1970), but not from anterior pereonites, which are setose. It has California (McCain 1975; Martin 1977). no cephalic projections. The entire second Caprella scaura (Templeton, 1836), a gnathopod (males) is setose in this species cosmopolitan species newly found in North (including the dactyl). The pereopodal America (Marelli 1981), is very like C. grasping spines (on propodus) are medial, not californica above, except that it lacks a ventral proximal as in C. drepanochir. Caprella spine between the gnathopods, and has two pilipalma has low tubercles dorsally, pairs of dorsal tubercles on pereonites five especially on its posterior segments. It has a (Marelli 1981). Pereonite four in adult males is small, erect, pointed, dorsally directed smooth dorsally in Caprella simia, a species cephalic spine (Dougherty and Steinberg introduced to southern California from Japan 1953) and its second gnathopods are (Watling and Carlton 2007). attached posteriorly to the second pereonites Obvious dorsal tuberculations on the in the male, and anteriorly in the female pereonites (lacking in C. drepanochir) (contrast C. drepanochir). The large propodus characterize the group composed of C. on the male gnathopod two has no poison alaskana, C. ferrea, C. incisa, C. mutica, C. spine or grasping spine, but does have many pilipalma and C. verrucosa. Caprella alaskana long colorless hairs (Dougherty and Steinberg has quite variable dorsal pereonite spines. It 1953). Caprella verrucosa has large, blunt has long first antennae, but the flagellum is tubercles on all pereonites, it is the most shorter than the peduncle, not longer. The tuberculate of this group. Unlike many of the male second antenna is shorter than the first genus, C. verrucosa and C. drepanochir have two articles of the first antenna. Like C. an antennal peduncle which is scarcely drepanochir, C. alaskana has a first pereonite setose (Dougherty and Steinberg 1953). The not more than twice the length of its head propodus on the second gnathopod in C. (Keith 1971). It is an intertidal species, found verrucosa is shorter than the second in Alaska and British Columbia, Canada pereonite (Keith 1971). This species has an (Martin 1977). Caprella ferrea has a pair of anteriorly directed triangular cephalic small blunt spines on its head (Laubitz 1970). projection (Keith 1971). Found in Puget The dorsal pereonite tubercles become large Sound (Keith 1971), California, British spines in the posterior pereonites (Keith Columbia, Japan (Martin 1977). Some 1971). The first pereonite in the male is about specimens of C. verrucosa from protected as long as the head (Keith 1971). C. ferrea waters have a ventral spine between the can be similar to C. alaskana above in its second gnathopods, in contradiction to most juvenile and immature stages, but not as an keys (Marelli 1981). adult (Laubitz 1970). Found in Alaska, British There are two other Caprella species, Columbia and in Puget Sound (Keith 1971; which, like C. drepanochir, have no cephalic Martin 1977). Caprella incisa has small spines, no ventral spines between the dorsal tubercles on its pereonites, the gnathopods, and no dorsal pereonite

Hiebert, T.C. 2015. Caprella drepanochir. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. projections: C. gracilior, and C. laeviuscula. Habitat: Substrate determined by food Caprella gracilior is occasionally found source as caprellids can cling to almost any intertidally, but usually inhabits deep water surface. They can be found on algae, (below 9 m, Laubitz 1970). It has a smooth sponges, etc., but do not like sandy or muddy body, except for two tubercles on pereonite bottoms (McCain 1975). five. The grasping spines on the slender Salinity: Collected at salinities of 30 (in Coos pereopod propodus are medial (not proximal Bay). as in C. drepanochir). The basis of the male Temperature: Primarily an Arctic species in gnathopod two is much longer than the protected, cold-temperature zones (e.g. propodus and the dactyl is setose (Laubitz Prince William Sound, AK) (Laubitz 1970). 1970). It has been reported from Alaska, Tidal Level: Intertidal (Laubitz 1970) and Washington, and California, but not from subtidal. Oregon (Laubitz 1970). Caprella laeviuscula Associates: These specimens were is the most common northeastern Pacific collected with Obelia sp. from floating docks, species (Laubitz 1970), and would be but can also occur with the congener Caprella expected to be found intertidally in Oregon's mutica. In Japan, they are commonly estuaries. It is the species most similar to C. associated with Tubularia sp. drepanochir in (according to McCain 1975, Abundance: Locally common in Coos Bay which does not include C. drepanochir). The (Charleston boat basin), especially in July. main difference is in the gills: they are long One of the most abundant epifaunal species and oval in C. laeviuscula and round in C. in eelgrass (Zostera marina) communities in drepanochir. The male second gnathopod in San Francisco Bay, California (Carr et al. C. laeviuscula has an extremely large poison 2011) and Willapa Bay, Washington (Ferraro spine (it is larger in C. drepanochir). The and Cole 2007). female gnathopod twp in C. laeviuscula is Life-History Information attached near the middle of the pereonite Reproduction: Development in most (Laubitz 1970) (contrast Fig. 2). Caprella amphipods is direct, lacking a larval stage. laeviuscula has a wide northern Pacific Little is known about the reproduction and distribution from Japan, to Alaska, British development in C. drepanochir. Eggs carried Columbia and south to Monterey, California by female in marsupium (Fig. 2), until they (Martin 1977). hatch at 0.4–0.5 mm. Caprella carina, a boreal species, Larva: No larval stage is observed per se, apparently washed ashore in Coos Bay but its instead small adult-like juveniles hatch from local establishment is unknown (Jessen 1969; female marsupium and grow to 1 mm long. Watling and Carlton 2007). Some stay in marsupium until mother's first molt (Japan, Kawana, in Arimoto et al. 1976; Ecological Information Wolff 2014). Range: Original description (and presumed Juvenile: Some Caprella juveniles cling to type region) from coast of China (Laubitz their mother’s body and grow through four 1970; Mayer 1890; Guerra-Garcia and molts over a period of 16 days. These Takeuchi 2003). An amphi-Pacific species juveniles are protected and groomed by their with a range extending from (Laubitz 1970) mother (e.g. Caprella monoceros, Aoki and Japan, Russia, the Arctic and Alaska as far as Kikuchi 1991) and this extended parental care Prince William Sound. Caprella drepanochir has been observed in a number of caprellids is an introduced species to the northeast (Thiel 1997). In other species juveniles do Pacific coast and was introduced in ship not cling to their mother’s body, but remain fouling from Asia (e.g. Japan) to San near her, attached to algae, where they Francisco Bay, California (Carr et al. 2011) receive protection from predators and other and Oregon (Watling and Carlton 2007). caprellids (e.g. Caprella decipiens, Aoki and Local Distribution: Coos Bay sites, Kikuchi 1991). including dock-side at the Charleston small Longevity: boat basin. Growth Rate: Amphipod growth occurs in conjunction with molting where the

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12700 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] exoskeleton is shed and replaced. Post-molt 4. CARR, L. A., K. E. BOYER, and A. J. individuals will have soft shells as the cuticle BROOKS. 2011. Spatial patterns of gradually hardens (Ruppert et al. 2004). epifaunal communities in San Caprellids undergo repeated moltings as they Francisco Bay eelgrass (Zostera grow and individuals of a single species can marina) beds. Marine Ecology. 32:88- show great variability in size depending upon 103. their age (Arimoto et al. 1976). Sexually 5. DOUGHERTY, E. C., and J. E. mature females are 7.5 mm in length, while STEINBERG. 1953. Notes on the males are 18 mm (Arimoto et al. 1976). skeleton shrimps (Crustacea: Food: Caprellids can eat many things by Caprellidae) of California. Proceedings different methods. Presence of plumose of the Biological Society of setae on second antennae provides the ability Washington. 66:39-49. to filter food and to scrape periphyton from 6. FERRARO, S. P., and F. A. COLE. surfaces to which they cling (Caine 1977) 2007. Benthic macrofauna habitat (e.g. Obelia, in Coos Bay). Some individuals associations in Willapa Bay, will nip off hydroid polyps as well as diatoms Washington, USA. Estuarine Coastal or detritus (Kozloff 1993). When feeding, the and Shelf Science. 71:491-507. caprellid hangs on with prehensile pereopods 7. GUERRA-GARCIA, J. M., and I. and uses antennae and gnathopods for TAKEUCHI. 2003. The Caprellidea eating. (Malacostraca, Amphipoda) from Mirs Predators: Caprellids are fed upon by Bay, Hong Kong, with the description bottom fishes (cod, blennies, skates, sea of a new genus and two new species. bass), also by shrimp, anemones (McCain Journal of Crustacean Biology. 1975), and hydroids (e.g. Candelabrum 23:154-168. fritchmanii, Hewitt and Goddard 2001). 8. HEWITT, C. L., and J. H. R. Behavior: Movement is inchworm-like: GODDARD. 2001. A New species of grasping substrate with large anterior large and highly contractile hydroid in gnathopods, then pulling up posterior and the genus Candelabrum (Hydrozoa : grabbing on with pereopods and posterior Anthoathecatae) from southern appendages. Oregon, USA. Canadian Journal of Zoology. 79:2280-2288. Bibliography 9. JESSEN, M. P. 1969. The ecology and taxonomy of the Caprellidae 1. AOKI, M., and T. KIKUCHI. 1991. Two (order: Amphipoda; Suborder: types of maternal care for juveniles Caprellidea) of the Coos Bay, Oregon, observed in Caprella monoceros area. Ph.D. University of Minnesota. (Mayer, 1890) and Caprella decipiens 10. KEITH, D. E. 1971. Substrates (Mayer, 1890) (Amphipoda, election in caprellid amphipods of Caprellidae). Hydrobiologia. 223:229- Southern California, with emphasis 237. on Caprella californica Stimpson and 2. ARIMOTO, I., D. KYOTO, and J. Caprella equilibra Say (Amphipoda). SETO RINKAI. 1976. Taxonomic Pacific Science. 25:387-394. studies of Caprellids (Crustacea, 11. KOZLOFF, E. N. 1993. Seashore life Amphipoda, Caprellidae) found in the of the northern Pacific coast: an Japanese and adjacent waters. Nihon illustrated guide to northern California, Warekararui Shuppanbu, Yokohama. Oregon, Washington, and British 3. CAINE, E. A. 1977. Feeding Columbia. University of Washington mechanisms and possible resource Press, Seattle, WA. partitioning of the Caprellidae 12. LAUBITZ, D. R. 1970. Studies on the (Crustacea: Amphipoda) from Puget Caprellidae, (Crustacean, Amphipoda) Sound, USA. Marine Biology. 42:331- of the American North Pacific. National 336. Museum of Natural Sciences (Ottawa)