BULLETIN OF MARINE SCIENCE, 27(4): 704-728, 1977
LARVAL DEVELOPMENT OF CALLINECTES SIMILIS REARED IN THE LABORATORY
C. G. Bookhout and J. D. Costlow, Jr.
ABSTRACT Freshly hatched larvae of Callinectes similis Williams, the lesser blue crab, were reared to the first crab stage. Eight zoeal stages and one megalopa stage are described with par- ticular reference to types of setae on appendages. Updated information on the develop- ment of the commercial blue crab, Callinectes sapidus Rathbun, is also given, as well as similarities and differences between C. similis and C. sapidus. The zoeae of C. similis and C. sapidus are so similar that they can only be separated by a number of minor differences. The dorsal spine of C. similis is significantly longer than that of C. sapidus in all zoeal stages. Other structures, such as the rostrum and antennae, are either longer in early zoeal stages of C. sapidus than in C. simi/is, or the structures of the two species are not significantly different. In later stages, however, structures measured were gen- erally significantly longer in C. similis than in C. sapidus. Also in later zoeal stages, there are generally small differences in setation of appendages. There are diagnostic differences in lengths of parts of the claw of the first leg and setation of pleopods of the megalopa of the two species. There are also minor differences in the setae of the scaphognathite, in seta of the epipodite of the 3rd maxilliped and in aesthetascs of antennules of the two species.
A number of genera, Callinectes, Portu- to the megalopa stage: Portunus pelagicus nus, and Arenaeus, belonging to the subfam- (Linnaeus) (Kurata and Midorikawa, 1975) ily Portuninae, are found in North Carolina and Thalamita sima (Herbst) (Kurata, 1975). waters (Williams, 1965), but the complete Attempts to rear other species of Portunus, larval development of only Callinectes sapi- Charybdis, and Thalamita of Japanese wa- dus Rathbun (Costlow and Bookhout, ters to crab or megalopa have failed. 1959) and Portunus spinicarpus (Stimpson) The present study is part of a general pro- (Bookhout and Costlow, 1974) have been gram to rear all species of Portuninae in the described from rearing. North Carolina waters from hatching to first The swimming crabs of the subfamily crab stage. Until this is done it is unlikely Portuninae comprise one of the most domi- that one could determine the larval distribu- nant groups of crabs which support impor- tion of the commercially important blue crab, tant fisheries along the Pacific, East China because the larvae of the subfamily Portuni- Sea, and Japan Sea coasts. Hence, there nae are so similar that it is difficult to distin- have been intensive efforts to rear species guish species. Kurata (1975) also notcd of Portunus, Charybdis, and Thalamita in that zoeae of Portuninac are so much alike the laboratory (Yatsuzuka, 1952, 1957; that the identification of species is practically Kurata, 1975; Kurata and Nishina, 1975; impossible without studying almost every and Kurata and Midorikawa, 1975). The minor difference. only Japanese species of Portuninae which The current study deals with the larval have been reared from hatching to first crab development of Callinectes similis Williams, are Charybdis japonica A. Milne Edward the lesser blue crab. It is difficult to distin- (Yatsuzuka, 1952, 1957) and Portunus tri- guish immature males and adult females of tuberculatus Miers (Kurata, 1975). How- C. similis from C. ornatus Ordway and C. ever, two Japanese species have been reared danae Smith (Williams, 1974). The geo- 704 BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SlMILlS 705 graphical distribution of C. similis is from were changed daily to clean bowls of sea- Delaware Bay to Key West, Florida, and water and fed one medicine dropper full of from northwestern Florida around the Gulf Arbacia embryos and the same volume of of Mexico to Campeche, Yucatan. Callinec- freshly hatched nauplii of Artemia salina tes ornatus is also found off the North Caro- hatched from San Francisco eggs. Larvae lina coast but its range is from North Caro- of C. similis are so small that they can con- lina through southern Florida, northwestern sume only parts of Artemia nauplii. Hence, Yucatan to Estado de Sao Paulo, Brazil, and the smaller Arbacia embryos serve as a valu- Bermuda. Callinectes danae does not occur able food supplement. off the North Carolina coast but has a Larvae were fixed at each developmental range from southern Florida and eastern stage in 70% alcohol and also in 70% ethyl- side of Yucatan Peninsula to Estado do ene glycol. Chromatophore patterns were Santa Catarina, Brazil, and is also found in sketched from the Jiving zoeae and megalopa. Bermuda (Williams, 1974). C. similis is, Drawings of larvae and their appendages therefore, the most northern species of the were made from fixed larvae and preserved three and is usually found in salinities above exuviae. Appendages were dissected and 15%0 in North Carolina and Florida. In mounted on slides in ethanol and glycerine. Mississippi Franks et al. (1972) reported Drawings were made on squared paper with that C. similis was caught in trawl samples the aid of a Whipple disc mounted in an at depths from 9 to 92 m at temperatures ocular of a compound microscope. The from 13.2 to 29.0°C and in salinities rang- Whipple disc was calibrated with a stage ing from 24.9 to 37.4%". micrometer. Whole mounts were examined The major objectives of this investigation under a magnification of 100x and appen- were: ( 1) to rear C. similis from the time dages under 200x. Details of appendages of hatching until the first crab stage is and setae were studied under a magnification reached; (2) to give a detailed description of 400x and under oil immersion lens. of each larval stage with emphasis on the Measurements of the combined carapace number and type of setae on each appen- and abdominal lengths, lengths of antennae, dage; and (3) to determine the chief charac- lengths of rostral and dorsal spines and teristics which distinguish the larvae of C. widths between lateral carapace spines were similis from C. sapidus. made to determine if there were significant differences between larvae of C. similis and MATERIALS AND METHODS C. sapidus. Ten C. sapidus larvae hatched from one mother crab and 10 C. similis Ovigerous Callinectes similis were col- larvae hatched from each of three different lected in trawl samples in the vicinity of the mother crabs, designated as C. simi, C. sim2, Beaufort Inlet, North Carolina. In the lab- and C. sima, were measured (Table 1). oratory, eggs were removed from the female, Similar measurements were made of larvae washed and placed in flasks or in compart- in zoeal stages II-V. Not enough larvae mented boxes of filtered seawater at a salin- ity of 30%c. The containers of eggs were from C. sim2 survived to measure after stage maintained on an Eberbach variable speed V or from C. sima after zoeal stage VII. shaker until hatching, following the proce- Hence, comparison between C. sapidus and dure described by Costlow and Bookhout C. similis were between 10 larvae of each (1960). After hatching, the larvae were species in zoeal stage VIII and megalopa reared in mass cultures. Initially about 700 (Table 1). A single classification ANOV A newly hatched larvae were placed in large with equal sample sizes was calculated and finger bowls (19.4-cm diam) containing a comparison of means was made to deter- 307<" filtered seawater. The living larvae mine if the means of each structure mea- 706 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 sured in C. sapidus were significantly differ- ent from the means of similar structures in C. similis. Measurements of the total length were made from the base of the rostrum to the c~ end of the telson. This was calculated by the addition of carapace length with the ab- dominal length from the middle of the sec- D ond segment, where it emerges from the posterior margin of the carapace, to the pos- terior tip of the telson. Measurements were E made of the dorsal spine from the point of emergence from the carapace to the tip, the rostral spine from the frontal edge of the orbital socket to the tip, and the antenna from the point of articulation with the cara- pace to the tip. The spine tip width was F calculated as the distance between the tips G of lateral carapace spines as seen from frontal view.
RESULTS Types of setae Figure 1, A-E This is the second paper in which there Figure 1. A-E. Additional types of setae on has been an attempt to determine the type developmental stages of Subfamily Portuninac not reported by Bookhout and Costlow, 1974. F-G. and location of setae on all appendages in Frontal views of lOeal stage I of C. similis and the development of a crab following the ter- C. sapidus: A, papillate; B, stout serrate; C, minology used by Thomas (1970) in his heavy toothed serrate; D, long toothed serrate; study of setae of crayfish, Austropotamobius E. fine serrate; F, frontal view of C. similis; G, pallipes (Lereboullet) . In the first paper, frontal view of C. sapidlls. the larval development of Portunus spini- carpus (Bookhout and Costlow, 1974), most types of setae found in the development of four types of serrate setae on the 3rd maxil- crabs in the subfamily Portuninae were de- liped of the megalopa of C. similis and P. scribed. During the course of the current spinicarpus: (a) stout serrate seta has a study several additional types were observed heavy shaft with horn-shaped, forward-pro- jecting serrations along the shaft (Fig. 1, B). in both Portunus spinicarpus and Callinec- (b) heavy toothed serrate seta has a heavy tes similis. These are shown in Figure 1 and shaft, but the serrations are thin, blade-like described below: 1. Papillate setae (Fig. 1, and forward curved so that they almost over- A) occur on endite edges of maxillae and lap each other (Fig. 1, C). (c) long toothed 1st maxillipeds of the crayfish, Austropoto- serrate seta has a long tapering shaft with mobius pallipes (Thomas, 1970). They are finer blade-like setules than described in the found on the endites of maxillae in C. similis heavy toothed serrate seta (Fig. 1, D). and P. spinicarpus and are characterized by (d) fine serrate seta has a long tapering shaft, a snout-shaped pore and several setules but the serrations are short and closely along the shaft. 2. Serrate setae. There are spaced (Fig. 1, E). BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SIMILTS 707
9
6
Figure 2. Pattern of chromatophores on schematic sketches of zoea of C. similis: A, side view; B, ventral view; C, lateral view of 1st leg of megalopa. Further explanation in text. 708 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977
Chromatophores many as eight. The chief morphological Figure 2, A-C characters of each developmental stage fol- low: The pattern of chromatophores of C. simi- First Zoea (Fig. 3, A-H).-The cephalo- lis is fairly consistent throughout zoeal de- thorax has dorsal, rostral and lateral spines velopment. The chromatophores are di~- which in 30 specimens have an average mea- grammed and numbered in Figure 2. A paIr surement of 0.341 mm, 0.220 mm, and of reddish orange chromatophores appears 0.116 mm, respectively (Fig. 3, A, B; Ta- on the postero-Iateral portion of abdominal ble 1). A small seta is found between the segments 3-5 (Fig. 2, Nos. 1, 2, and 3) and dorsal and lateral spines (Fig. 3, B). Eyes are extends into the adjacent segment by a ven- not stalked. The abdomen consists of five tral-posterior extension. Single chromato- segments plus a telson. There are lateral phores of the same color appear on the projections on each abdominal segment with basipodite and coxopodite of the 1st maxilli- the exception of the 1st (Fig. 3, B). The ped (Fig. 2, Nos. 4 and 5), the coxopodite lateral projections of the 2nd segment are of the 2nd and 3rd maxilliped (Fig. 2, Nos. short rounded knobs; the 3rd segment bears 6 and 7) and the basipod, carpopod and a small downward pointed hook on each dactylopod of the claw (Fig. 2, Nos. 8, 9 side. Segments 3-5 have postero-lateral and 10). spines (0.02 mm, 0.015 mm, and 0.01 mm A large black chromatophore and a large in length) which overlap the adjacent seg- red chromatophore appear on the mandible, ment (Fig. 3, A and B). A pair of short a red and black one on the labrum, and a setae project from the posterior dorsal sur- black one above the mandibular muscle pos- face of segments 2-5 (Fig. 3, A). terior to the eye (Fig. 2, Nos. 11, 12 and Each ramus of the furcal arch of the tel- ] 3). A black chromatophore also appears son bears a small dorsal (Fig. 3, A) and a posterior to the mandible and anterior to large lateral spine (Fig. 3, A, B). Three the coxopodite of the 1st maxilliped (Fig. serrate spines occur on the inner margin of 2, No. 14). Red chromatophores are on each furcal ramus, the inner spine having the bases of the antennae, antennules and several stiff setules along its inner border. rostrum (Fig. 2, Nos. 15, 16 and 17). The conical antennule bears three termi- Blackish red chromatophores are located nal aesthetascs, one simple hooked seta and dorsally as follows: one anterior to the stom- two or three short hair-like setae (Fig. 3, C; ach, two over the stomach, one of which Table 2). The latter may be overlooked for extends over the front of the heart (Fig. 2, they are difficult to see. Nos. 18, 19 and 20), and one around the The antenna has an elongated protopodite intestine in the first and second abdominal with two rows of minute spines on its distal segment (Fig. 2, No. 21). In addition, two half and an exopodite which is approximately or three blackish chromatophores may be 0.05 mm long with a long and short terminal seen over the lateral portions of the stomach seta (Fig. 3, D). which extend outwards and downwards The mandibles are asymmetrical and have (Fig. 2, No. 22). three elevated cutting ridges. The setae on coxal and basal endites of Description of Developmental Stages the maxillule are given in Table 3 (Fig. 3, E) . The endopodite is two-segmented with There are usually seven zoeal stages and four plumodenticulate setae terminally and one megalopa stage in the complete larval two subterminally. development of Callinectes similis. Occa- The setae of the proximal and distal lobes sionally life histories of this species, how- of the coxal and basal cndites of thc maxilla ever, may have but six zoeal stages, or as are given in Table 4 (Fig. 3, F). The proxi- BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SlMILlS 709
,1 mm f-----i
A B
D
E
1.05 mm 1
,.1 mm
Figure 3. Zoea T of C. simi/is: A, side view; B, ventral view; C, antennule; D, antenna; E, maxi!- lule; F, maxilla; G, first maxilliped; H, second maxilliped. 710 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977
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Setation of antennules of Callinectes similis and Callinectes sapidus -.~------Callinectes similis CaIlinectes sapidus Hair- Hair- Hooked like Hooked like Aesthctases Setae Setae Aesthetases Setae Setae Zoea I 3T IT 2-3T 3T IT 2-3T Zoca II 4T IT 2-3T 4T IT 2-3T Zoca III 4T IT 2-3T 4T IT 2-3T Zoea IV 4T IT 2-3T 4T IT 2-3T Zoca V 4T, Is IT 2-3T 4T, Is IT 2-3T Zoea VI 4T, 2s IT 2-3T 4T, 2-3s IT 2-3T Zoea VII 4T, 5s IT 2-3T 4T, 5s IT 2-3T Zoea VIII 4T, 6s, 6s IT 2-3T 4T, 6s, 5s IT 2-3T Acsthetases Plumose Simple Aesthetases Plumose Simple Megalopa Outer Ramus 2nd Seg. llT lOT 3rd Seg. lOT IT 9T IT 4th Seg. 8T 3T 8T 3T 5th Seg. 5s IT Is 4s IT Is Inner Ramus 4T,2s 4T,2s T = terminal; S = subterminal. mal lobe of the endopodite bears one long stalked and a pair of short slender spines has plumodenticulate and one short plumose been added to the central arch of the telson seta, and the distal lobe bears one long (Fig. 4, B). The mean increase in lengths plumodenticulate and two to three short of carapace, abdomen, dorsal and rostral plumose setae. The scaphognathite bears spines and total length of the protopodite of four plumose setae anteriorly and margin- the antenna compared to lengths of similar ally and one long plumose seta posteriorly structures in the 1st zoeae is given in Table 1. (Fig. 3, F). The antennule bears four terminal aesthet- The exopodite of the 1st maxilliped bears ascs, one hooked seta and two or three short four natatory plumose setae and the five- hair-like setae (Fig. 4, C; Table 2). segmented endopodite has setation from the The total length of the protopodite of the base to the tip of 2, 2, 0, 2, 5 (Fig. 3, G). antenna has grown as shown in Table 1, The exopodite of the 2nd maxilliped bears whereas the exopodite remains unchanged four natatory plumose setae and the three- (Fig. 4, D). segmented endopodite has a serrate seta on The mandible shows no perceptible the basal and middle segment and five setae change. on the terminal segment (Fig. 3, H). The The setation of the coxal endite of the latter include one long plumose, one long maxillule is the same as in the 1st zoea, and serrate, and three small simple setae. the setation of the endopodite is unchanged, The 3rd maxilliped has not developed. but a long plumose seta has been added be- low the base of the endopodite (Fig. 4, E). Second Zoea (Fig. 4, A-F).-The charac- The setation of the proximal and distal ters of the cephalothorax and abdomen are lobes of the coxal and basal endites of the similar to the 1st zoea except the eyes are maxilla is given in Table 4 (Fig. 4, F). The 712 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 .1mm J.----i .01mm f---l Figure 4. Zoea II of C. similis: A, side view; B, ventral VIew; C, antennule; D, antenna; E. maxil- lule; F, maxilla. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SIM1L/S 713 .lmm t----' Figure 5. Zoea III of C. simi/is: A, side view; B, ventral view; C, antennllle; D, antenna; E, mandi- ble; F, maxillllle; G, maxilla. proximal lobe of the endopodite has one plumose setae anteriorly and marginally, and long plumodenticulate and one short plu- three posteriorly (Fig. 4, F). mose seta; the distal lobe has one long The 1st and 2nd maxillipeds have exopo- plumodenticulate and three short plumose dites with six natatory setae; setation of the setae. The scaphognathite has five to six endopodites is unchanged (Fig. 4, A, B). 714 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 Table 3. Comparative setation of maxillule of Callinectes similis and Callinecles sapidus Callinectes similis Callinectes sapidlls Coxal Endite Subterminal Border Subterminal Border Terminal Proximal Distal Terminal Proximal Distal Zoea I 5 : 2 Old, 2 pld, 1 s 1 s. 5: 2 Old, 2 pld, 1 s. 1 s. Zoea II 5: 2 Old, 2 pld, 1 s 1 pI. 5: 2 Old, 2 pld, 1 s. 1 pI. Zoea III 7: 3 Old, 2 pld, 2 s 1 pI. 7 : 3 Old, 2 pld, 2 s. 1 pI. Zoea IV 7: 4 md, 2 pld, 1 d. 1 pI. 7: 4 Old, 1 pld, 2 d. 1 pI. Zoea V 7: 4 Old, 2 pld, 1 d. 1 pI. 7: 4 Old, 2 pld, 1 d. 2 pI. Zoea VI 7: 4 md, 2 pld, 1 d. 2 pI. 1 pI. 7: 4 Old, 2 pld, 1 d. 2 pI. 1 pI. Zoea VII 8 : 5 Old, 2 pld, 1 d. 3 pI. 1 pI. 8: 4 Old, 2 pld, 2 d. 3 pI. 2 pI. Zoea VIII 8 : 5 Old, 2 pld, 1 d. 3 pI. 2 pI. 8 : 5 Old, 2 pld, 1 d. 4 pI. 2 pI. Megalopa 8: 5 md, 2 pld, 1 d. 5 pI. 5 pI. 8 6 pI. 4 pI. Basal Endite Subterminal Subterminal Terminal Border Terminal Boarder Zoea I 5 : 2 pld eus, 3 pld 5: 2 pld eus 3 pld Zoea II 7: 4 pld eus, 3 pld 7 : 4 pld eus 3 pld Zoea III 8: 4 pld eus, 4 pld 1 pld 8: 4 pld eus 4 pld 1 pid Zoea IV 9 : 5 pld eus, 4 pld 1 pld 8: 4 pld eus 4 pld 1 pid Zoea V 11 : 5 pld eus, 6 pld 2 pld 10: 5 pld eus 5 pid 1 pid Zoea VI 13 : 5 pld eus, 8 pld 2 pld 11 : 5 pld eus 6 pld 1 pld Zoea VII 14 : 5 pld eus, 9 pld 3 pld 13 : 5 pld eus 8 pld 2 pld Zoea VIII 16: 5 pld eus, 11 pld 3 pld 16: 5 pld eus 11 pld 2 pld Megalopa 26 : 8 pld eus, 12 pld 6 d. 3 pld 23 : 8 pld eus 10 pld 5 d. 5 pld md == multidenticulate; pld cus == plumodenticulate cuspidate; pld == plumodenticulate; pI. == plumose; s. == simple; d. == denticulate. Third Zoea (Fig. 5, A-G).-The mean ~n- endopodite bears the same setation as in the crease in lengths of body regions and spines 2nd zoea. The scaphognathitc has eight an- compared to lengths of similar structures in terior and marginal plumose setae and five the 2nd zoea is given in Table 1. The sixth posteriorly. abdominal segment is present, but it lacks The exopodites of each of the 1st and spines (Fig. 5, A, B). 2nd maxillipeds bear eight natatory setae. The antennule (Table 2) and antenna The endopodites of the 1st maxilliped bear have the same setation as in the 2nd zoea 2, 2, 0, 2, 6 setae, respectively, on segments (Fig. 5, C, D). 1-5. The setation of the endopodite of the The mandibles are asymmetrical and 2nd maxilliped remains unchanged. each has three rows of teeth. Figure 5, E, shows two rows on a raised plateau and an- Fourth Zoea (Fig. 6, A-G).-The mean in- other row on a separate plane. crease in lengths of body regions and spines The setation of the coxopodite and basip- compared to the lengths of similar structures odite of the maxillule is given in Table 3 in the 3rd zoea is given in Table 1. The fur- (Fig. 5, F). The setation of the endopodite cal arch of the telson now bears three inner is the same as in the 2nd zoea. small spines (Fig. 6, B). The setation of the proximal and distal The antennule (Fig. 6, C) and antenna lobes of the coxal and basal endites of the (Fig. 6, D) have the same setation as in the maxilla is listed in Table 4 (Fig. 5, G). The previous stage. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SIMILIS 715 -a-a'a'a-a-a-a-a-a "='''='''='''='''=' "='''='''='''=' .~'" NNNNNNNN' 0.0.S::;c:i;c:i;c:i;c:i;c:i;c:i; 0.0.0.0.0.0.0.0.0. NNNNN<'\<'\<'\" "='''='"tl"tl"tl"tl"tl''='"tl 0.0.0.0.0.0.0.0.0. NNNNNN<'\<'\V) -0:0. -0:0. 0. -0:0:0, 0. NNNNNNNN' 0. 0. o,o,c:i;c:i;c:i;c:i;c:i; 0.0.0.0.0.0.0.0.0. NNNNN~('f"')rf")rf'1 o U'"" 'a'a'a'a'a-a-a-aP-. .:: "tl"tl"tl"tl"tl"tl"='''=' NNNNNNNNv) '".~ 0.0.0.0.0.0.0.0. ..0 ..0 ..0 ..0 '1:i '1:i. '1:i ..o 1)" NNNNNNN' "'0 "'0 "'0 "'0 "CI "'0 "tj ~ o:'Z.:o./E./a 0.. "a E ------00 "0 ~ ~ "tl"tl"tl"tl"tl"='''='''='''=' 0.0.0.0.0.0.0.0.0. NNNNNNN<'\<'\ -0:0. 0. -0:0. -0:0. -0:0. NNNNNNN<'\\O u 'i;j "tl "tl "tl "tl "=' "tl "=' ] 0. 0. 0. 0. 0. 0. 0. 1:i ---- .•....• _~ ~ o o,o.c:i;c:i;c:i;c:i;c:i;c:i;c:i; 0.0.0.0.0.0.0.0.0. e 0. NNNNN<'\' 1 rnm I~ ------i A c Figure 6. Zoea IV of C. similis: A, side view; B, ventral view; C, antennule; D, antenna; E, maxil- lule; F, maxilla; G, coxopod of 1st maxilliped. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLlNECTES SlMILlS 717 The mandible has not changed. The endopodite of ] st maxilliped has The setation of the coxopodite and basipo- a setation of 2, 2, 1, 2, 6 and the endopodite dite of the maxillule is given in Table 3 (Fig. of 2nd maxilliped has a setation of 1, 1, 5. 6, E). A small seta has been added to the The epipodite bud of the 1st maxilliped has proximal lobe of the endopodite. grown and the coxopodite has one hair-like The coxopodite, basipodite and endopo- seta as in Stage IV (Fig. 7, H). Exopodites dite of the maxilla remain unchanged. The of 1st and 2nd maxillipeds have 11 and 12 scaphognathite bears 17 to 20 plumose setae nata tory setae, respectively (Fig. 7, A, B). (Fig. 6, F; Table 5). The bud of 3rd maxilliped has two lobes The exopodites of the 1st and 2nd maxilli- (Fig. 7, I). Claw of 1st pereiopod bud peds have 9 and 10 natatory setae, respec- shows a slight bifurcation, but other buds tively. An epipodite bud is present at the are undifferentiated. All buds are longer base of the 1st maxilliped (Fig. 6, G). The than in the previous zoeal stage (Fig. 7, I). coxopodite of the 1st maxilliped bears one seta. The endopodite of the 1st maxilliped Sixth Zoea (Fig. 8, A-H).- The mean in- bears 2, 2, 1, 2, 6 setae, respectively, on crease in lengths of body regions and spines segments 1-5. Rounded buds of the 3rd compared to the lengths of similar structures maxillipeds and pereiopods are present un- in the 5th zoea is given in Table 1. der the carapace. The setation of the antennule is given in Table 2. Fifth Zoea (Fig. 7, A-I).-The mean in- The endopodite of the antenna is as long crease in lengths of body regions and spines as the exopodite and its longest seta (Fig. 8, compared to the lengths of similar structures D), or about one-third the distance from the in the 4th zoea is given in Table 1. The tel- base of the endopodite to the spines on the son now has four small inner spines in the protopodite. central arch (Fig. 7, B). The setation of coxal and basal endites of The setation of antennule is given in Ta- the maxillule is given in Table 3 (Fig. 8, ble 2 (Fig. 7, C). E). The endopodite proper remains un- The antenna shows a bud of the endopo- changed, but the simple hair-like seta below dite for the first time. It varies in size from the endopodite in the 5th zoeal stage has be- a distinct swelling to a short bud (Fig. 7, D). come finely denticulate. The mandibles appear the same as in the The setation of the proximal and distal 4th zoea (Fig. 7, E). The right and left lobes of co:xal and basal endites of the mandibles are asymmetrical. The setation of maxilla is given in Table 4 (Fig. 8, F). The the coxopodite and basipodite of the maxil- endopodite remains unchanged. Scaphogna- {lI{e is given in Table 3. The setation of the endopodite remains unchanged, but the seta thite has 26-28 marginal plumose setae which was simple on the basal segment in (Fig. 8, F; Table 5). the 4th zoeal stage is now plumose. Below The exopodites of 1st and 2nd maxillipeds the endopodite there are two setae, one have 12 and 14 natatory plumose setae, re- thickly pappose and the other simple (Fig. spectively. Setation of endopodites un- 7, F). changed (Fig. 8, A, B). Figure 8, G, shows The setation of the proximal and distal shape of epipodite bud of 1st maxilliped. lobes of the coxal and basal endites of the The coxopodite of the 1st maxilliped bears maxilla is given in Table 4 (Fig. 7, G). The two simple setae. setation of the endopodite is unchanged. The rudimentary 3rd maxilliped has three The scaphognathite has approximately 23 lobes for the first time. marginal plumose setae (Fig. 7, G; Table Pereiopod buds have lengthened but are 5). unsegmented (Fig. 8, H). Pleopod buds are 718 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 1------1 mm - ---i A B Figure 7. Zoea V of C. similis: A, side view; B, ventral view; C, antennule; D, antenna; E, mandi- ble; F, maxillule; G, maxilla; H, coxopod of 1st maxilliped; I, buds of 3rd maxilliped and pereiopods. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLTNECTES SIMILIS 719 Table 5. Setation of scaphognathite, exopods of maxillipeds, and te]son spines - Maxilla Exopods Seaphognathite ] st Maxilliped 2nd Maxilliped C. sim. C. sap. C. sim. C. sap. C. sim. C. sap. Zoe a I 5 5 4 4 4 4 Zoea II 8 8 6 6 6 6 Zoea III 13 13 8 8 8 8 Zoea IV 17-20 15 9 9 10 ]0 Zoea V 23 20-21 11 10 12 11 Zoea VI 26-28 25 12 11 14 13 Zoea VII 31-33 26-29 14 12 15 14 Zoea VIII 40 33-36 15 13 17 15 Short spines within center of furea of telson c. sim. C. sap. Zoea I o o Zoea II 2 2 Zoea III 2 2 Zoea IV 3 2 Zoea V 4 3 Zoea VI 4 3 Zoea VII 5 3 Zoea VIII 5 4 C. silll. = C. silllilis; C. sap. = C. sapidlls. perceptible for the first time on segments 2-6 The setation of coxal and basal endites (Fig. 8, A, B). of maxil/ule is given in Table 3. Three long Seventh Zoea (Fig. 9, A-J).-The mean in- setae are below the endopodite, one thickly crease in lengths of body regions and spines pappose and two plumodenticulate (Fig. 9, compared to the lengths of similar structures F). in the 6th zoea is given in Table 1. There The setation of proximal and distal lobes are now five small spines in the inner arch of coxal and basal endites of maxilla are of the telson (Fig. 9 B; Table 5). given in Table 4. The endopodite remains The setation of antennule is given in Ta- unchanged. The scaphognathite bears ap- ble 2. There is an indication of the place proximately 31-33 setae along its marginal where the inner ramus will form, but there border (Fig. 9, G; Table 5). is no protrusion (Fig. 9, C). The exopodites of 1st and 2nd maxillipeds The setation of antenna (Fig. 9, D) same have 14 and 15 natatory plumose setae, re- as in previous stage; endopodite four-fifths spectively (Table 5). The setation of endop- the distance from the base of the endopodite odites is the same as described in the 4th to the spines of the protopodite. zoeal stage. The coxopodite of the 1st maxil- The mandible acquires a bud of the man- liped bears two hair-like setae, and epipodite dibular palp. The raised plateau of two bud one hair-like seta (Fig. 9, H). rows of teeth described in Stage III now has The 3rd maxilliped is composed of three several rows of teeth. The third ridge re- lobes which show indications of segmenta- mains on a separate plane, essentially un- tion (Fig. 9, I). changed (Fig. 9, E). The pereiopods show indications of seg- 720 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 Imm ,.1 mm , Figure 8. Zoe a VI of C. simi/is: A, side view; B, ventral view; C, antcnnule; D, antenna; E. maxil- lule; F, maxilla; G, coxopod of 1st maxilliped; H, buds of 3rd maxilliped and pereiopods. mentation and 1st pereiopod is bifurcated Eighth Zoea (Fig. 10, A-D).-The mean (Fig. 9, J). increase in lengths of body regions and The pleopods are better developed than in spines compared to length of similar struc- the 6th zoeal stage, but they are not biramous tures in the 7th zoea is given in Table 1. (Fig. 9, A, B). The setation of the antennule is given in BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SlMILlS 721 I mm f------l H J Figure 9. Zoea VII of C. simi/is: A, side view; B, ventral view; C, antennule; D, antenna; E, man- dible; F, maxillule; G, maxilla; H, coxopodite of 1st maxilliped; I, bud of 3rd maxilliped; J, pereio- pods. 722 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 B c D ....•...------ Figure 10. Zoea VIII of C. simi/is: A, side view; B, ventral view; C, antennule; D, antenna; E, man- dible; F, maxillule; G, maxilla; H, coxopodite of 1st maxilliped; I, buds of 3rd maxilliped and pereiopods. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALL/NECTES S/MILIS 723 Table 2. The inner ramus is well developed setae, and an inflated 3rd segment with two for the first time (Fig. 10, C). plumodenticulate setae near the terminal The setation of antenna is unchanged; border (Fig. 11, D). The inner ramus bears the endopodite is three-fourths the length four terminal setae and two subterminal of protopodite (Fig. 10, D). setae. The outer ramus is five-segmented The mandible is characterized by elevated with no setae on the basal segment, 11 aes- ridges with rows of knobs and a few hair-like thetascs on the 2nd segment, 10 aesthetascs setae (Fig. 10, E). The bud of the palp is on the 3rd segment, 8 aesthetascs and one present. long and one short seta on the 4th segment, The setation of coxal and basal endites of 5 aesthetascs in a row from the middle of maxillule is given in Table 3 (Fig. 10, F). the terminal segment and a long stiff, plu- The endopodite remains unchanged. mose, terminal seta and one subterminal The setation of proximal and distal lobes seta (Fig. 11, D). of coxal and basal endites of maxilla is The antenna is composed of 11 segments, given in Table 4. The endopodite remains some of which bear setae, as shown in Fig. unchanged. The scaphognathite bears ap- 11, E. proximately 40 plumose setae along its bor- The mandible consists of a smooth cutting der (Fig. 10, G; Table 5). edge at the base of which is a palp which The exopodites of 1st and 2nd maxillipeds has 12 plumodenticulate setae and one sim- have 15 and 17 natatory plumose setae, re- ple seta on the terminal end of the distal spectively (Table 5). The endopod same as segment (Fig. 11, F). described in 4th zoeal stage (Fig. 10, A, B). The setation of coxal and distal endites The coxopodite of 1st maxilliped bears three of maxillule is given in Table 3 (Fig. 12, A). hair-like setae and epipodite bud has one The endopodite appears to lack segmenta- hair-like seta (Fig. 10, H). tion, and bears five setae as shown on Fig. The 3rd maxilliped and pereiopods are 12, A, with three setae below the endopo- longer than in zoeal Stage VII and show dite. signs of segmentation (Fig. 10, I). The setation of proximal and distal lobes The pleopod buds are longer than in pre- of coxal and basal endites of maxilla is given vious stage, and on abdominal segments 2-5 in Table 4 (Fig. 12, B). The endopodite has they are biramous (Fig. 10, B). lost its segmentation and has only three setae at its base. The scaphognathite has 68 Megalopa (Figs. 11, A-F and 12, A-E).- marginal and 12 submarginal plumose setae The carapace of C. similis is rectangular in (Table 6). outline, without dorsal or lateral spines. It The coxopodite of 1st maxilliped has 21 has a forward-projecting pointed rostrum denticulate and plumodenticulate setae, 9 of which is about one-half the length of an- which are subterminal and 12 near the ter- tenna (Fig. 11, A, B). A pair of spines ex- minal border. The basipodite is character- tends from the 4th sternal segment poste- ized by 30 marginal and 9 submarginal riorly beyond the base of the 5th leg (Fig. plumodenticulate setae. The endopodite 11, C). The 5th abdominal segment has a has six simple setae; exopodite is biseg- lateral spine which extends posteriorly be- mented with two long plumose setae on the yond the 6th segment (Fig. 11, A, B). On distal margin of the basal segment and five the ischiopodite of the cheliped there is a long plumose setae on the distal end of the strong hooked spine. The telson tapers to terminal segment. The epipodite is well de- a slightly convex border. veloped with six long simple setae basally The peduncle of antennule consists of a and 14 distally (Fig. 12, C). bulbous basal segment, an elongated 2nd The endopodite of 2nd maxilliped is five- segment with two distal, sparsely plumose segmented with three simple setae on basal 724 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 Figure 11. Megalopa of C. simi/is: A, side view; B, dorsal view; C, ventral view of abdomen; D, antennule, basal segment only partially shown; E, antenna; F, mandible. BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALUNECTES SIMILIS 725 1.1 mm I E Figure 12. Appendages of megalopa of C. simi/is: A, maxillule; B, maxilla; C, 1st maxilliped; D, 2nd maxilliped; E, 3rd maxilliped. 726 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 Table 6. Characteristics of C. sapidus and C. simi/is rnegalopa ------Carapace Abdomen Base of Propod Base of to Base of Daetylopod Length Width Length Width Rostrum Antenna Dactylopod to Tip .---.- A. Mean measurements in mm C. sapidus 1.65 1.1 1 1.25 0.46 0.43 0.88 0.49 0.46 C. similis 1.30 1.10 1.35 0.46 0.50 1.00 0.50 0.60 B. Setae on pleopods No. of plumose setae on exopods No. of hooks on endopods Abdominal segment 2 3 4 6 2 3 4 5 6 C. sapir/us 24 22 21 19 11 3-4 3 3 3 0 C. similis 22 21 20 19 11 4-5 4-5 4 4 0 C. Plumose setae on D. Long Simple Setae E. Aesthetascs on Outer Scaphognathite of on Epipodite of Ramus of Antennule Maxilla 3rd Maxilliped Terminal Subterminal Marginal Submarginal Proximal Distal Segment Segments ._---~------C. sapidus 63 8 4 ]4 4 10,9,8 C. similis 68 12 3 21 5 11,10,8 segment, five simple setae on 2nd segment, minal segment with 12 setae: 3 stout toothed one long plumodenticulate and two simple serrate, 4 long toothed serrate and 5 serrate setae on 3rd segment, two denticulate cus- setae. Epipodite characterized by 21 long pidate, four long fine denticulate and two simple setae distally and 3 simple setae ba- short simple setae on the 4th segment; sally (Fig. 12, E; Table 6). and seven medium to stout denticulate cus- The dactylopod of 1sf pereiopod is elon- pidate setae and three finely denticulate gated but shorter than opposing claw; setae on the terminal segment. The exopo- curved tips overlap. Carpopod without dite is two-segmented with no setae on the spines. Second, 3rd and 4th pereiopods basal segment and five plumose and one similar to each other (Fig. 11, A, B). Fifth simple seta on the distal segment (Fig. 12, pereiopod with paddle-shaped dactylopod D). bordered by eight long serrate hooked setae The exopodite of 3rd maxilliped is two- (Fig. 11, A, B). segmented with one short and five long The pleopods on 2nd-6th abdominal plumose setae terminally. The five-seg- segments with 22, 21, 20, 19, and 11 plu- mented endopodite includes the ischiopodite mose setae on the exopods, respectively; en- with 28 setae: 9 cuspidate denticulate, 12 dopods of the 1st two pairs of pleopods have fine denticulate setae marginally and 5 sim- 4-5 hooked spines, those of the 3rd and ple and 2 plumodenticulate setae submar- 4th pair have 4 hooked spines (Table 6; ginally; meropodite with 14 setae: 4 simple, Fig. 11, C). 8 denticulate, and 2 short denticulate; car- popodite with 11 setae: 7 serrate, 1 fine DISCUSSION serrate, 2 simple and 1 fine denticulate; propodite with 18 setae: 1 fine denticulate Differences between lOcal stages of and 1 simple distally, 10 long serrate along Callinectes similis and C. sapidus inner border, 3 fine serrate on one side and 1. MEASUREMENTS.Of all the structures 3 heavy serrate on the other side; and ter- measured and given in Table 1, the dorsal BOOKHOUT AND COSTLOW: LARVAL DEVELOPMENT OF CALLINECTES SIMILIS 727 spine is the only one which is significantly better developed in C. sapidus than in C. longer in C. simi/is than in C. sapidus in all similis. zoeal stages. 4. SETATIONOF ANTENNULES.The seta- Measurements of the combined lengths of tion of antennules of C. similis and C. sap- carapace and abdomen, referred to as total idus is similar on zoeal stages I-VII, but length in Table 1, lengths of rostral spines zoeal stage VIII has different setation (Ta- and antennae, and distance between tips of ble 2). lateral spines of the carapace show that in The setation of the antennu1e of C. sap- earlier zoeal stages structures are generally idus given in Table 4 of a paper by Bookhout either significantly longer in C. sapidus than and Costlow (1974) was based on a publi- in C. similis or there is no significant differ- cation by Costlow and Bookhout (1959). ence between measurements of structures of It did not include the hooked seta which is the two species. In later stages, however, listed in Table 2 of this paper. Callinectes the structures measured are generally signifi- sapidus data in Tables 1-6 have been up- cantly greater in C. simi/is than in C. sapidus dated since the papers on Portunus spini- (Table 1). carpus (Bookhout and Costlow, 1974) and In addition to the measurement of struc- on Callinectes sapidus (Costlow and Book- tures given in Table 1, it can be seen by in- hout, 1959) were published. spection that other characters of the two species have different dimensions. A frontal 5. SETATIONOF MOUTHPARTS. There are view of a zoea in stage I, and sometimes in slight differences in the setation of the stage II, shows that the carapace of C. sap- mouth parts of C. similis and C. sapidus as idus has a higher bell-shaped dome above shown in Tables 3 and 4. The scaphogna- the lateral carapace spines than C. similis thite of the maxilla from the 4th zoeal stage (Fig. ], G). The same area in C. similis is to the megalopa has more plumose setae in flatter and broader (Fig. 1, F). Further- C. simi/is than in C. sapidus (Table 5). more, the cndopodite of the antennae, leg buds and pleopod buds in zoeal stages V- Differences between megalopa of VIlI are generally longer and more devel- Callinectes similis and C. sapidus oped in C. sapidus than in C. similis. The clearest differences between the 2. TELSONS. In the first three zoeal megalopa of the two species are given in stages of C. similis and C. sapidus there is Table 6. In general C. similis megalopa has no perceptible difference in the telsons ex- a shorter carapace than C. sapid us, and C. cept for slight differences in length and similis has a longer rostrum and antenna width. From zoeal stages IV to VIII, how- (Table 6). The base of the prepod to the ever, there are generally more short spines in base of the dactylopod of the claw of first the central arch of the telson in C. similis leg of the two species is approximately equal, than in C. sapidus (Table 5). but the distal portion of the propod from the base of the dacty10pod to the tip is longer in 3. MAXILLlPEDS.The number of natatory C. similis than C. sapidus. The dactylopod plumose setae on the exopodites of the 1st of C. similis is also longer than that of C. and 2nd maxillipeds of C. similis and C. sapidus (Table 6). In the megalopa of C. sapidus are the same in the first four zoeal similis there are fewer plumose setae on the stages, but in zoeal stages V to VIII C. exopods of the first three pairs of pleopods similis generally has more natatory setae on and more hooked spines on the endopods of the exopodites of the maxillipeds (Table 5). the first four pairs of pleopods than in C. The three lobes of the 3rd maxilliped in sapidus. There are also differences in the zoeal stages V-VIII are slightly larger and number of setae on the scaphognathite, in 728 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.4, 1977 the long simple setae of the epipodite of the Kurata, Hiroshi. 1975. Larvae of Decapoda 3rd maxilliped, and in the aesthetascs of the Brachyura of Arasaki, Sagami Bay V. The swimming crabs of the subfamily Portuninae. antennules of the two species (Table 6). Bull. Nansei Reg. Fish. Res. Lab. 8: 39-65. ---, and S. Nishina. 1975. The zoeal stages ACKNOWLEDGMENTS of the swimming crabs, Charybdis japonica and The authors wish to express their appreciation Port un us hastatoides reared in the laboratory. to Mrs. Doris King for assistance throughout this Bull. Nansei Reg. Fish. Res. Lab. 8: 21-27. study and to Mrs. Roselind Cronin and Miss Judy ---, and T. Midorikawa. 1975. The larval Clarke Edwards for their technical assistance in stages of the swimming crabs, Portunus the initial stages of the research. pelagicus and P. sanguinolentus reared in the The research was supported in part by the Duke laboratory. Bull. Nansei Reg. Fish. Res. Lab. Research Council and by the U.S. Atomic En- 8: 29-38. ergy Commission (Grant No. AT-(40-1)-4377). Thomas, W. J. 1970. The setae of Austropota- It constitutes a contribution of the Zoology De- mobius pal/ipes (Crustacea: Astacidae). 1. partment, Duke University, and the Duke Uni- Zoo I. London. 160: 91-142. versity Marine Laboratory. Williams, Austin B. 1965. Marine decapod crustaceans of the Carolinas. Fish. Bull. Fish LITERATURE CITED Wildl. Servo U.S. 65: 1-298. 1974. The swimming crabs of the Bookhout, C. G., and J. D. Costlow, Jr. 1974. genus Cal/inectes (Decapoda: portunidae). Larval development of Portunus spinicarpus Fish. Bull. 72: 685-798. reared in the laboratory. Bull. Mar. Sci. 24: Yatsuzuka, K. 1952. The metamorphosis and 20-51. growth of the larva of Charybdis japonica Costlow, J. D., Jr., and C. G. Bookhout. 1959. A. Milne Edward. Bull. lap. Soc. Scient. The larval development of Callinectes sapidus Fish. 17-22. Rathbun reared in the laboratory. BioI. Bun. 1957. Study of Brachyuran zoea, artifi- Mar. BioI. Lab. Woods Hole, 116: 373-396. cial rearing and development. Sursagaku 1960. A method for developing brachy- Shusei, pp. 571-590. Univ. of Tokyo Press. uran eggs in vitro. Limnol. Oceanogr. 5: (In Japanese.) 212-215. Franks, 1. S., 1. Y. Christmas, W. L. Siler, R. Combs, R. Waller, and C. Burns. 1972. A DATE ACCEPTED: September 17, 1976. study of nektonic and benthic faunas of the shallow Gulf of Mexico off the state of ADDRESSES:(CCB) Department of Zoology, Duke Mississippi as related to some physical, chemi- University, Durham, North Carolina 27706; (iDC) cal and geological factors. Gulf Res. Rep. Duke University Marine Laboratory, Beaufort, 4: 1-148. North Carolina 28516.