THE POST-EMBRYONIC DEVELOPMENT OF THE COMMON PANDALIDS OF BRITISH COLUMBIA

Abstract

The paper deals with the post-embryonic development of the five most common pandalids in British Columbia, namely. Pandalus danae, Pandalus borealis, Pandalus hypsinotus, Pandalus platyceros, and Pandalopsis dispar, in greatest detail with the first species, with which the others are compared. The first stage of post-embryonic development was obtained for each species by hatching the eggs in the laboratory. Later larval stages were obtained from plankton collections, and all known stages were described and illustrated. All five species tend to be more fully developed on hatching than is normal for Caridea. The individuals of each species all undergo a change of sex, functioning first as males and later as females, the time spent in each phase varying in different species. Pandalus danae spends about eighteen months in the male phase, P. borealis and P. hypsinotus each spend about thirty months, while P. platyceros and Pandalopsis dispar are about forty-two months old before they begin to change to the female phase. The rate of growth is similar in all for the first summer, and then begins to vary. Differences in the rates of growth of the different species may partly be caused by variations in the rapidity with which they mature as males, and in the length of time spent in the male phase. Only for Pandalus danae has the rate of increase of weight been considered, and it was found to increase approximately as the cube of the length.