FISHERY BULLETIN: VOL. 74, NO. 2 



ing a segmented scale. Laboratory-reared Stage I 

 zoeae known by me to possess a segmented scale 

 are Pandalopsis dispar, Pandalus stenolepis, P. 

 goniurus, P. borealis, P. danae, P. hypsinotus, and 

 P. platyceros. Berkeley obviously failed to recog- 

 nize the segmented scales on her specimens. 

 Therefore, Price and Chew's (1972) suggestion 

 that Lebour's grouping for classifying the early 

 stages of pandalid zoeae using segmentation of 

 the antennal scale be disregarded is valid. 



In most Decapoda, the development of func- 

 tional pleopods provides a convenient and clear 

 distinction between the zoeal and postzoeal 

 stages because it is accompanied by several other 

 abrupt changes in morphology, such as loss or re- 

 duction of some or all of the thoracic exopodites 

 and changes in shape and body proportions. In 

 the Pandalidae, however, there is not always an 

 abrupt metamorphosis at this molt. Pike and 

 Williamson (1964) discussed how in P. montagui 

 the pleopods may become fully functional before 

 the exopodites on the pereopods show any 

 reduction; in P. danae the exopodites on the 

 pereopods and the third maxilliped degenerate 

 before the pleopods become functional; and in P. 

 kessleri Czernaivski the exopodites on the per- 

 eopods never become functional. In my zoeae the 

 development of functional pleopods occurred at 

 Stage VII, but other morphological changes 

 normally associated with postzoeal metamorpho- 

 sis occurred earlier, especially at the molt to 

 Stage IV. Morphological changes that occurred at 

 the molt to Stage VI are reduction of thoracic 

 exopodites; loss of supraorbital spines; changes in 

 color; changes in shape of rostrum, mandibles, 

 and second maxilliped; and segmentation of 

 carpopodite of the second pereopod. Depending 

 upon one's definition of "megalopa," it may be 

 valid to consider Stage VII of P. hypsinotus as the 

 megalopa; or one may consider stages IV through 

 VII are all megalopal or the term "megalopa" is 

 not strictly applicable to P. hypsinotus. 



In addition to the morphological changes noted 

 above, abbreviated development of zoeae of P. 

 hypsinotus is also indicated by the occurrence of 

 thoracic exopodites on pereopods 1 and 2. In con- 

 trast, most Pandalidae without abbreviated de- 

 velopment have thoracic exopodites on pereopods 

 1-3. A notable exception is zoeae of P. platyceros, 



which have thoracic exopodites on pereopods 1-3 

 but only four zoeal stages and 8 + 8 telson setae in 

 Stage I rather than the usual 7 + 7. Another 

 feature of abbreviated development in P. hypsi- 

 notus is the proximal extension and occurrence of 

 17 setae on the exopodite of the maxilla in Stage 

 I. Usually the exopodite of the maxilla in Stage I 

 of the Caridea has no proximal extension and 

 only five setae, as in the protozoea of the 

 Peneidea and most British Pandalidae (Lebour 

 1940; Gurney 1942). The abbreviated develop- 

 ment of zoeae of P hypsinotus agrees with the 

 findings of Berkeley (1930), who noted that zoeae 

 of most Pandalidae of the northeast Pacific tend to 

 be more developed when they hatch than is normal 

 for Caridea. 



ACKNOWLEDGMENTS 



D. I. Williamson of the University of Liverpool, 

 England, and C. Nyblade of the University of 

 Washington, Seattle, read an earlier version of 

 this manuscript and offered suggestions for 

 improvement. 



LITERATURE CITED 



Berkeley, A. A. 



1930. The post-embryonic development of the common 

 pandalids of British Columbia. Contrib. Can. Biol. 

 6:79-163. 



Gurney, R. 



1942. Larvae of decapod Crustacea. Ray Soc. Publ. 129, 

 306 p. 

 KURATA, H. 



1964. Larvae of decapod Crustacea of Hokkaido. 3. Pan- 

 dalidae. Bull. Hokkaido Reg. Fish. Res. Lab. 28:23-34. 

 Lebour, M. V. 



1940. The larvae of the Pandalidae. J. Mar Biol. Assoc. 



U.K. 24:239-252. 

 MODIN, J. C, AND K. W. Cox. 



1967. Post-embryonic development of laboratory-reared 



ocean shrimp, Pandalus jordani Rathbun. Crustaceana 



13:197-219. 



Pike, r. b., and D. L Williamson. 



1964. The larvae of some species of Pandalidae (Decapo- 

 da). Crustaceana 6:265-284. 



Price, V. A., and K. K. Chew. 



1972. Laboratory rearing of spot shrimp larvae (Pandalus 

 platyceros) and description of stages. J. Fish. Res. Board 

 Can. 29:413-422. 



Williamson, D. I. 



1969. Names of larvae in the Decapoda and Euphausia- 

 cea. Crustaceana 16:210-213. 



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