Embryonic development of the red snow crab <italic>Chionoecetes japonicus</italic> (Decapoda: Oregoniidae), inhabiting the meso and bathypelagic zones of the Sea of Japan.

This study investigated the seasonal changes in embryonic development of the red snow crabs inhabiting the deep sea using wild and captive ovigerous females. The embryonic stages were categorised into 14 groups based on their external morphology. Females with recently spawned eggs (between stage 1 and early stage 3), those with the eggs at the midterm stage (mainly stages 7 and 8), and those with eggs just before hatching (stage 14) were observed simultaneously from January to March indicating a 2-year reproductive cycle. These findings aid in understanding and identifying the spawning years of the red snow crabs sampled from their natural habitats. [ABSTRACT FROM AUTHOR]