On the chromosomes of three species of deep-sea crabs

Abstract

The present paper deals with the chromosomes in the male germ cells of the following three species of the deep-sea crabs (Decapoda, Reptantia), which were obtained from the Suruga Bay, west of Izu Peninsula, at depths of 200 to 400 meters; Macrocheira kampferi, Nephropsis carpenteri and Nephrops japonicus. The numerical relations of the chromosomes existing in these species of crabs here investigated and morphological features of their chromosomes may be clearly understood from the following table and by reference to the accompanying figures (cf. Figs. 1-14).It is noteworthy that the tetrads (bivalent chromosomes) observed in the primary spermatocyte of Nephropsis carpenteri do not assume the usual type of compact dumbbell shape widely seen in Decapoda in general, but each consists of well differentiated quadripartite chromatic elements. The fact that about a half of all the tetrads in the closely related species, Nephrops japonicus, possess a similar quadripartite structure, seems to suggest a systematical relationship existing between the two species.In none of the cases described above, was there any evidence for the presence of the particular chromosomes, either in behaviour or in structure.