Fisheries Science 63(6), 923-930 (1997)

Functional Morphology of Mouthparts and Foregut of the Last Zoea, Glaucothoe and First Juvenile of the King Paralithodes camtschaticus, P. brevipes and P. platypus

Fernando A. Abrunhosa and Jiro Kittaka

Research Institute for Marine Biological Science, Research Institute for Science and Technology, The Science University of Tokyo, Onnemoto, Nemuro, Hokkaido 087-01, Japan (Received March 24, 1997)

The feeding apparatus of the Paralithodes camtschaticus, P. brevipes and P. platypus during the transition zoea, glaucothoe and first juvenile stages were analyzed. The mandibles of zoeal larvae are well adapted for grinding of food. The mandibles of the glaucothoe are uncalcified and rudimentary, and the mandibular lateral lobes are apparently incapable of giving support to the masticatory move ment. The setae of endopods and endites of the maxillae and endopods of the first and second maxil lipeds are substituted for minute setae or denticles. The third maxilliped appear to be apparently devel oped, but the crista dentata on the ischium is still not formed. The first juvenile has well calcified mandi ble. The crista dentata on the third maxilliped is completely formed. The setose zoeal foregut has two chambers distinctively separated by a heavily setose cardiopyloric valve. The pyloric stomach has a well developed filter press. The glaucothoe has the foregut chambers and the cardiac pyloric valve unarmed or with few small setae present. The gastric mill and lateral teeth appear for the first time in the juvenile foregut. These observations indicate changing in the feeding of lithodids, in which they abstain from feeding during the glaucothoe stage. Key words: anomura, king , zoea, glaucothoe, 1st juvenile, morphology, mouthparts, foregut

The genus Paralithodes comprises the well-known fish puerulus and/or glaucothoe stages in regard to their sur eries resources known as in the North Pacific vival strategies before and after settlement. Larval culture Ocean: P. camtschaticus, P. brevipes and P. platypus.1) is much easier for king crab than spiny . Therefore, Research has been carried out to clarify the early life histo useful information may be provided by the studies on king ry and to establish a larval culture method for resource crab. In this study, detailed structural features of the management and enhancement.2,3) The larvae hatch out as mouthparts and foregut were investigated for king crab in zoea, metamorphose into glaucothoe and then moult to relation to the developmental stages. juveniles.2-6)Although the technology for culture has been developed to some extent, lack of detailed studies on mor Materials and Methods phological and physiological features of the digestive sys tem in relation to feeding habit makes it difficult to estab Larval Culture lish a mass culture method in the true sense. Egg-bearing females of P. camtschaticus, P. brevipes In early studies, the mouthparts of zoeal instars, glau and P. platypus were collected in northeastern Hokkaido, cothoe and first juveniles were described for P. camtschati Japan in December 1995. The larvae hatched out in March cus by Sato2) and for P. brevipes by Kurata4) and for P. 1996 for P. brevipes and P. platypus, and in April 1996 for platypus by Sato2) and Hoffman.6) These authors noticed P.camtschaticus. The newly-hatched zoea were trans atrophy of the mouthparts for the glaucothoe and as ferred to aerated tanks (capacity: 100-2000 1). Water tem sumed that it reflects a change in the feeding habits. Re perature was maintained at 8ß to 12•Ž. Zoeae were fed Ar cently, the results of culture experiments strongly suggest temia nauplii and cultured diatom (Thalassiosira sp.), ed that glaucothoe is a non-feeding stage.*1 The metabolicc separately or in combination. Glaucothoe were transferred mechanism during the non-feeding stage has an important t to separate tanks and no food was given. role in the settlement strategies of the glaucothoe and its understanding would be helpful in developing mass larval Gross Morphology culture methods. Mouthparts were examined from individuals and exu Evidence of non-feeding after metamorphosis has been viae of the last zoea, glaucothoe and first juvenile instars observed in the puerulus of spiny .7-11) It is im fixed in 10% formalin solution buffered with sodium phos portant to clarify the metabolic mechanism during the phate. Exuviae were dissected under a binocular micro-

*1 J. Kittaka: Non-feeding stage of some larvae and its implication in . The Fifth International Working Group on Crustace - an Nutrition Symposium, April 22-24, Kagoshima, Japan (1995) (submitted). 924 Fernando A. Abrunhosa and Jiro Kittaka

scope and diagrammatically illustrated (including illustra connective tissue, 14)and immersed in solution 1:1 of 70% tion of the larvae foreguts). The general description of the ethanol and glycerin. mouthparts was based on our observations and citations The terminology used in the description for foregut of of previous reports.2,4-6) metamorphosed forms follows Nishida et al.,7) and that of The setal types were described based on our observation Meiss and Norman,15) Suthers and Anderson,) and Icely and on the descriptions in previous reports for H. america and Nott17) for foregut of the first juveniles. nus.12,13) as follows: Serrulate type 1-Long and medium setae with short and Results rigid setules arranged in a row near the base to distal end ing and forming an angle of 180ß. The morphology of mouthparts and foreguts of the Serrulate type 2-Short and medium with setules similar three examined were remarkably similar in general to type I but arranged in a row from the medial to the dis terms. However, some specific features are included in the tal portion similar to serrulate type (F2) described for lar following descriptions. vae of H. americanus. Serrulate type 3-Similar to type (1) but shorter and stout . Gross Morphology of the Mouthparts er, and the setules shorter on the distal portion. Ia. Last zoea instar Plumodenticulate-Similar to plumose setae, but with set Mandibles (Fig. IA; 2A) ules on the final ending being short, forming an angle of The lateral lobes are enlarged and well developed; the 180ß. palp is anteriorly present, unsegmented and unarmed (ab The foreguts were observed from 10 individuals of each sent in the Alaska specimen P. platypus).6) The gnathal species fixed in 10% neutral formalin. The individuals lobes are asymmetrical, each with a flat incisor process and were immersed in 20 ml of 5% aqueous solution of KOH a large molar process. heated to 80•Ž for about 30 min for the zoeae and glau The right mandible has an incisor process bearing a cothoes and 12 h for the first juveniles. The foreguts were strong ventral tooth; the lateral margin has 3 or 4 cristae of removed with fine needles under a binocular microscope, acute teeth bordered with a series of denticles; the molar stained with 0.1% azorcarmine G or with aniline blue and process has 3 wide projections (inferior more prominent), orange G solution, which are staining solutions used for and several acute and blunt denticles on the distal and dor-

Fig. 1. Diagram of ventral view (left side) of the maxillipeds of last zoea instar, glaucothoe and first juvenile of the Paralithodes species: A, last zoea instar (Showing left mandible, 1st and 2nd maxillae and maxillipeds). Exopod of maxillipeds not drawn; B, glaucothoe and C, 1st juvenile (MP1•Œ and MP2•Œ showing in detail the 1st and 2nd maxillipeds, of the 1st juvenile, respectively). (Scale bar=0.5 mm) Abbrev.: CD=Crista dentata; MAD=Mandible; MPl=First maxilliped; MP2=Second maxilliped; MP3=Third maxilliped; MX1=First maxilla; MX2=Second maxilla.

1 Mouthparts of Larva and Postlarva of King Crab 925 sal surfaces. medium plumodenticulate setae distally and 1+2 short The left mandible has the incisive process bearing teeth plumodenticulate setae on the subdistal margin. on the lateral margin less prominent than those of the right Second maxilla (Fig. 2G) mandible; the molar process is larger than the incisor proc The scaphognathite has a well developed heavily setose ess with a rounded edge holding several denticles, and anterior lobe; the posterior lobe is rudimentary and un blunt teeth on the inner surface; and the ventral surface armed. The endopod is armed with 3+1 spaced plumose has a series of acute denticles (about 6) arranged in a semic setae on the distal and subdistal portions, and 2 spaced ircle. plumose and 1 simple long setae on the proximal margins. First maxilla (Fig. 2D) The basal and coxal endites are bilobed and armed with The endopod is 3-segmented with 3 long and spaced se long plumose and plumodenticulate setae distally and 1 tae on the distal segment, 1 long-spaced plumose on the subdistally. medial segment, and 2 short simple setae on the proximal First maxillioed (Fie. 1A) segment. The basal endite is wide with 4 to 6 strong cuspi The first maxilliped is 5-segmented and armed distally date setae distally and 2 medium plumodenticulate setae with long serrulate (type 1) setae and l medium plumose on the subdistal margin. The coxal endite is armed with 6 on the outer margin; the other segments have medium and

Fig.2. Diagram of the mouthparts of the Paralithodes species: A-C, mandibles; D-F, 1st maxillae; G-I, second maxillae; A, last zoea instar; B, glau cothoe; C, 1st juvenile; D, last zoea instar; E, glaucothoe; F, 1st juvenile; G, last zoea instar; H, glaucothoe; I, 1st juvenile. (Scale bar =0.2 mm) Abbrev.: BE=Basal endite; CE=Coxal endite; END=Endopod; GL=Gnathal lobe of mandible; LL=Lateral lobe of mandible; MAP=Man dibular palp; SCA=Scaphognathite. 926 Fernando A. Abrunhosa and Jiro Kittaka long plumose setae on the inner margin, and plumose setae um seta. (on 3rd, 4th and 5th) on the outer margin. The basal endite 1 c. First Juvenile (basis) has long and medium plumose setae distally, and Mandible (Fig. 2C) medium simple and plumose seta on the medial and prox The lateral lobe is staff-shaped and calcified solidly; the imal margins. The coxal endite has I medium to long palp is 3-segmented with the distal segment heavily armed plumose seta. with short hamate setae. The gnathal lobes are asymmetri Second maxilliped (Fig. 1A) cal, well developed, blade-shaped, having blunt teeth dor The second maxilliped is 4-segmented and armed distal sally. ly with long serrulate (type 1) setae and 1 medium plumose on the outer margin; the other segments have 1 medium to The endopod has the proximal and distal segments with long plumose and I strong medium serrulate (type 3) setae an acute spine-like seta distally. The basal endite is heavily on the inner margin, the 2nd and 3rd segments have 1 long armed with strong teeth distally and plumose or plumoden plumose seta on the outer margin. The basal endite has I ticulate setae on the subdistal and lateral margins. The cox medium plumose and 1 medium serrulate seta (type 3) onn al endite is more enlarged, and the distal and lateral mar the distal margin and 1 medium serrulate (type 2) on the gins are fully setose with serrate and plumose setae. medial margin. No setae are present on the coxal endite. Second maxilla (Fig. 21) Third maxillived (Fig. 1A) The endopod ends in a distal acute spine and a plumose The third maxilliped is rudimentary with 2 distinct seg seta medially. The basal and coxal endites have a larger ments; the distal segment is shorter than the 2nd segment number of setae, which are a compound of mainly medi with I medium serrulate (type 1) seta distally and I long um to long plumodenticulate setae; the proximal lobe of plumose subdistally; the 2nd segment has a long serrulate the coxal endite has long plumose setae in the lateral mar (type 1) seta distally. No setae are present on the basal and gin; the distal lobe of the coxal endite is encircled with coxal endites. medium plumose setae on the lateral and medial portions. lb. Glaucothoe First maxilliped (Fig. IC, see detail MPI•Œ) Mandibles (Fig. 2B) The endopod is indistinctly segmented with 3 to 5 long The lateral lobe is rudimentary and uncalcified; the palp plumose setae marginally. The basal and coxal endites are is 3-segmented, unarmed or with few small denticles on the heavily setose with strong spines, medium serrulate setae distal segment. The gnathal lobe is spoon-shaped, lacking (type 2) and plumose setae marginally. teeth, and similar in form to that of the first juvenile; the Second maxillived (Fig. 1C. see detail MP2•Œ) incisive and molar processes are indistinguishable. The shape is similar to that of previous instars. The dac First maxilla (Fig. 2B) tyl has strong medium serrate setae distally, and medium The endopod has minute spine-like setae present on the and short serrulate marginally; the propodus has the distal tip, rarely in the other segments. The basal endite has 3 to portion enclosed with long serrulate setae; the merus has 4 small setae on the lateral margin. The coxal endite is larg long plumose setae on the inner margin; the ischium and er than that of previous instars with 4 to 5 minute setae dis coxal endites have 2 and 4-8 long plumose setae marginal tally. ly, respectively. The number of setae in the basal and coxal Second maxilla (Fig. 2H) endites of endopod increased; the basal endite has 4 to 5 The scaphognathite has the anterior and posterior lobes long plumose setae. well developed and heavily setose. The endopod lacks se Third maxilliped (Fig. 1C) tae, although a minute spine-like simple seta sometimes is The shape is similar to those of previous instars. The car present in P. camtschaticus. The basal and coxal endites pus increased in setae number; the ischium has a promi are similar to that of the last zoea instar in shape but lack nent tooth and a strong serrate seta on the inner dorsal setae or have few short plumose or hamate setae. margin, and a row of 6 to 8 blunt teeth (crista dentata) ven First maxilliped (Fig. 1B) trolaterally. The first maxilliped is reduced in size. The endopod is in distinctly segmented, lacks setae or has few minute spine 2. Gross Morphology of the Foregut like setae along the inner margin. The basal and coxal en 2a. Last zoea (Fig. 3A; 4A) dites are incompletely fused bearing few minute spine-like The foregut wall is chitinous and flattened laterally. The or small setae marginally. cardiac and pyloric stomachs are separated by a prominent Second maxilliped (Fig. 1B) cardiopyloric valve. The second maxilliped is short. The endopod is 4-seg The cardiac stomach is narrow and long (about 1.5 mented. The basal and coxal endites lack setae or have few times longer than the pyloric stomach), lacking gastric minute simple or spine-like setae on the inner margin. teeth, and is covered heavily with numerous long setae Third maxilliped (Fig. 1B) (blisters); the cardiac floor is rugged and apparently lacks The endopod is 5-segmented, well developed and heavi brushes. The cardiopyloric valve is V-shaped, bent to the ly armed with long and medium setae; the dactyl has 4 to 5 pyloric stomach, and armed with strong spines surperficial long serrate setae distally, and a tuft of medium serrate se ly. tae are arranged in a row on the inner margin; a tuft of ser The pyloric stomach is rectangularly shaped and slightly rate setae is present on the propodus and carpus; the me larger than the cardiac stomach; the dorsal surface and rus is armed with few medium and short simple setae; the posterior portion have long spines; the median portion is ischium has a stout denticle ventrolaterally (the crista den armed with a vestigial and uncalcified anterior and the mid tata is not developed). The coxal endite has a single medi- dle pleuropyloric ossicles; the filter press is well developed Mouthparts of Larva and Postlarva of King Crab 927

with the dorsal brush bearing long setae . 2b. Glaucothoe (Fig. 3B; 4B) The foregut is chitinous, quite similar in shape to that of the last zoea instar. The cardiac stomach has few minute setae on the oe sophageal valve; the cardiac wall is unarmed, rarely bear ing fine minute setae; the cardiac floor has the dorsal sur face of lateral ridge similar to the last zoea; the cardiopyloric valve has reduced denticles (absent in P. brevipes). The pyloric stomach has numerous small setae present on the dorsal and posterolateral walls; the vestigial an terior and middle pleuropyloric ossicles are present and armed with small denticles and setae almost undetected un der microscope; the filter press is flatter than previous in stars with fine small setae and minute spinules present on the dorsal brush. 2c. First Juvenile (Fig. 3C:.4C) The foregut is very complex. The gastric mill has ossicles solidly calcified, mainly on the cardiac stomach. The cardiac stomach (about 1.5 times larger than the pyloric stomach) is enlarged dorsolaterally by heavily cal cified mesocardiac, urocardiac, pterocardiac and zygocardic ossicles. Each zygocardiac ossicle (one pair) has a screw-shaped lateral tooth (Fig. 4D) (the medial teeth were not observed); the supporting ossicles (prepecti nal, postpectinal, pectinal and sedentary ossicles) and the ventral and inferior lateral cardiac ossicles are present; the posterior, anterior and lateral plates are present. The cardiopyloric valve is similar to that of previous instars in shape. and armed dorsally with snipe-like setae. The pyloric stomach is more complex than those of the previous instars, the pyloric ossicles are less calcified than the cardiac ossicles; the filter press is apparently smaller than that of the last zoea foregut.

Discussion

Last Zoea Instar 1. Mouthparts In decapod larvae, the mandibles are the main food processing mouthpart.181 The mandibles of the examined species, remarkably large and complex, and appear well adapted for the grinding of planktonic food. In zoea lar vae mandibles are the only structure with such a function Fig. 3. Diagram of lateral view of foregut of the Paralithodes species: in the digestive system. A, last zoeal instar; B, glaucothoe and C, first juvenile. Some types of setae found in the three lithodid species, (Scale bar: A and B=0.33 mm and C=0.5 mm) unlike those described for H. americanus,12,13)mainly have Abbrev.: AMP=Anterior mesopyloric ossicle; AP=Anterior those relative to the position of the setules. The long and pleuropyloric ossicle (a pair); C=Cardiac stomach; CF=Cardiac specialized setae observed in the first and second maxillae floor; CPV=Cardiopyloric valve; EXP=Exopyloric ossicle; suggest that the larvae are adapted for manipulating food FP=Filter press; I=Intestine; ILC=Inferior lateral cardiac ossicle; LPV=Lateral pyloric valve; LT=Lateral tooth (a pair); MP=Mid including retention of small particles, such as microalgae. dle pleuropyloric ossicle (a pair); MSC=Mesocardiac ossicle; However, the survival of the larvae in this experiment was OES=Oesophagus; P=Pyloric stomach; PC=Pectinal ossicle; negatively affected when they were fed exclusively with PIV=Posterior pyloric valve; PIV=Pyloric intestinal valve; Thalassiosira sp. Similar results were obtained when PLCP=Posterior lateral cardiac plate; POP=Postpectinal ossicle; Paralithodes camtschaticus were fed exclusively Skeletone PP=Posterior pleuropyloric ossicle; PPC=Prepectinal ossicle; ma costatum.191 The best development was observed, in the PRP=Propyloric ossicle; PSA = Posterior supra ampullary ossicle; PTC=Pterocardiac ossicle; PY=Pyloric ossicle; SD=Subdentate present experiment, for larvae fed Artemia nauplii and dia ossicle; UP=Uropyloric ossicle; URC=Urocardiac ossicle; tom (Thalassiosira sp.), in combination, mainly for P. ZYC=Zygocardiac ossicle. camtschaticus. The endopods of the second and third maxillipeds are well adapted for capturing prey. A detailed description for 928 Fernando A. Abrunhosa and Jiro Kittaka

Fig. 4. Light microscope photographs of foregut of the Paralithodes species: A, zoea foregut of P. platypus (•~ 100); B, glaucothoe foregut of P. platypus (•~ 100); C, first juvenile foregut of P. camtschaticus (•~40); D, Detail of lateral tooth in the first juvenile of P. camtschaticus foregut (•~ 400). Abbrev.: c = Cardiac stomach; cpv = Cardiopyloric valve; fp =Filter press; It =Lateral tooth (a pair); oes=Oesophagus; p=Pyloric stomach.

capturing prey by the endopod of the maxillipeds in Glaucothoe anomuran larvae was reported by Gonor and Gonor.20) 1. Mouthparts The endopod of the 2nd maxilliped (Fig. IA) is more Drastic morphological changes in the mouthparts and robust than the 1st maxilliped and seems well adapted for foregut of the larvae of crustacean decapods are observed holding prey because of the features of serrulate setae after moulting of the last zoea instar. Recently, this mor present on the inner margin. The third maxillipeds set dis phological change has been suggested to indicate that the tantly from the mandibles having rudimentary endopods puerulus of spiny lobsters is a non-feeding stage.7,8,10) and basipods and do not execute any feeding function. The external feeding apparatus of glaucothoes are ana 2. Foregut tomically different from those of the last zoea instar. They The zoea foreguts of the three species have no lateral resemble in shape the respective parts in the first juvenile teeth and ossicles of the gastric mills are still not devel but with endopods of the maxillae and maxillipeds (except oped. However, the foregut wall, cardiopyloric valve and the third maxilliped) unarmed or bearing small setae or the filter press are largely setose. These features are similar denticles. The mandibles are uncalcified and with the later to those of related palinurid species in which the function al lobe rudimentary and apparently incapable of giving of the foregut was considered to be not for grinding but support to the normal masticatory movement of the mandi for the mixing of food 7,10,21) Similar observations were ble. reported for the zoea larvae of the stone crab Menippe mer Alterations occur also in the position of the maxillipeds. cenaria.18.22) The mandibles and maxillae of the glaucothoes are co vered by the maxillipeds (Fig. 1B) like in adult of anomu rans and brachyurans. The manipulation and ingestion of food are mainly accomplished by the coordinator action Mouthparts of Larva and Postlarva of King Crab 929 of the mandibles and teeth on the ischium of the third max Non feeding Behaviour in the Glaucothoe Stage illipeds (crista dentata) in adult Homa The anatomy of the mouthparts and foreguts of the rus americanus,131 and in adult for examined glaucothoes suggests that the glaucothoe stage peronii.'t For an analogy, though the distal segments of abstains from feeding during this instar and that they cor glaucothoes (dactyl, propodus and merus) are well devel respond to those reported for the puerulus of the spiny lob oped, the crista dentata on the ischium is still not formed, ster. This is consistent with the facts that individuals suggesting that it does not have a masticatory function. reared in the laboratory showed no feeding behavior and 2. Foregut successfully developed into the first juvenile stage. The general form of the foregut in glaucothoe is not al The absence of feeding in the glaucothoes was also sug tered after metamorphosis. However, the quantity and gested in pagurid Pagurus benhardus from biochemical size of pectinate setae (=bristles) are reduced in the cham analyses, 24)and from rearing experiments in P. midden bers of the foregut. The glaucothoes have no lateral teeth, dorfii and P. pectinatus. *2 It will be necessary, however, to and no alterations are observed in the rudimentary ossicles examine evidence of non-feeding during the glaucothoe in the zoea larvae. The absence of setae for mixing food in stage in other anomuran species. glaucothoe, in contrast to their presence in zoea larvae, Some lithodids have, however, complete lecithotrophic and the absence of gastric mills in glaucothoe foregut sug development. Larvae of the northern stone crab, Lithodes gest that the glaucothoe stage is a non-feeding stage. These maja,25) and golden king crab, L. aequispinus, *3 successful facts are similar to those of the puerulus of the spiny lob ly developed from hatching to the first benthic instar ster. 7,8,10) without feeding. Similar development was reported for the lithodid Paralomis granulosa,26) which, when either First Juvenile starved or fed larvae, successfully developed into glau 1. Mouthparts cothoe. However, both groups of glaucothoe failed to The laminar structure of the mandibles of the first moult into first juveniles. The external feeding appendages juveniles suggests that the mandibles are well adapted for of glaucothoes described for L. aequispina27) and Paralo cutting food and apparently they do not grind as they were mis hystrix28) are similar to those observed species in the observed to do in the zoea larvae. The setae on the end present study, in that the mandibular palp, the endopods opods and maxillipeds, mainly those on the proximal seg and endites of the maxillae and the first and second maxil ments (coxa, base and ischium), are increased in number lipeds have reduced number of setae. These facts suggest and become specialized. The crista dentata on the ischial that some anomuran species have interesting feeding segment in the third maxilliped is completely formed. The habits. Further studies are needed to understand their feed feeding apparatus of the first juvenile of edwardsii is ing characteristics and nutrition. capable of masticating large, hard or soft materials.7) The same conclusion can be applied to the first juvenile stage Acknowledgments We would like to express our sincere thanks to Dr. of the species in this study. In our laboratory, the first S. Nishida of the Ocean Research Institute, University of Tokyo for his valuable suggestions on the present study and to Mr. S. Onoda and Mr. juvenile stages of P. camtschaticus and P. brevipes have R. Kudo who worked in the larvae culture in Nemuro and supplied the been successfully cultured on a diet of mussels and pellets samples of P. camtschaticus and P. brevipes investigated in this study. A used for juveniles of the Penaeus japonicus. part of this study was supported by a Grant-in-Aid for Scientific 2. Foregut Research (c) (No. 07660257) from the Ministry of Education, Science, The enlargement of the cardiac foregut suggests the Sport and Culture of Japan. juveniles are well adapted for eating large food particles. The ossicles of the gastric mills are similar to those of References adult anomurans and brachyurans described by Meiss and Norman,15)and to those of the first juvenile stage of stone 1) W. E. Dawson: King crabs of the world (Crustacea: Lithodidae) crab Men lime mercenaria described by Factor.22) and their fisheries. A comprehensive bibliography. Miscellaneous Publication 101, New Zealand Oceanographic Institute, Wellin Several studies have clarified the grinding function of gton, 1989, p. 338. the lateral teeth of decapod . 13,16-18,22,23)The 2) S. Sato: Studies on larval development and fisheries biology of king function of gastric mills can be divided into two move crab, Paralithodes camtschatica (Tilesius). Bull. Hokkaido Reg. ments, biting and grinding. These movements are conduct Fish. Res. Lab., 17, 1-102 (1958) (in Japanese). ed by specific muscles related to the medial and lateral 3) T. Nakanishi and M. Naryu: Some aspects of large-scale rearing of teeth.23)In the palinurid I. peronii, the major masticatory larvae and post-larvae of the king crab (Paralithodes camtschatica). Bull. Japan Sea Reg. Fish. Res. Lab., 32, 39-47 (1981). action of the gastric mill is a cutting action of the lateral 4) H. Kurata: The larval stages of Paralithodes brevipes (, teeth.16)The screw-shaped lateral teeth (see detail, Fig. 4D) Anomura). Bull. Hokkaido Reg. Fish. Res. Lab., 14, 25-34 (1956) of the three first juveniles species observed in this study ap (in Japanese). pear to be well adapted for grinding large and hard food. 5) H. Kurata: Larvae of Decapod Crustacea of Hokkaido. 6. Lithodi This fact was confirmed by the feeding behavior showed dae (Anomura). Bull. Hokkaido Reg. Fish. Res. Lab., 29, 49-65 by the first juveniles of P. camtschaticus and P. brevipes (1964) (in Japanese). reared in the laboratory. 6) E. G. Hoffman: Description of laboratory-reared larvae of (Decapoda, Anomura, Lithodidae). J. Res. Fish. Bd. Canada, 25, 439-455 (1968).

*2 F. A. Abrunhosa and J. Kittaka: Abst. Metg. Japan. Soc. Fisheries Sci., September, 1995, p. 85. *3 C . T. Shirley and S. Zhou: Lecithotrophic development of the golden king crab Lithodes aequispinus (Anomura, Lithodidae). J. Crust. Biol. (in press). 930 Fernando A. Abrunhosa and Jiro Kittaka

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