DEVELOPMENT OF THE OMMASTREPHID SQUID TODARODES PACIFICUS, FROM FERTILIZED EGG TO RHYNCHOTEUTHION PARALARVA

The present study establishes for the first time an atlas for the norm al development of Todarodes pacificus Steenstrup, 1880, from fertilize d egg to rhynchoteuthion paralarva. In the course of the study, observ ations on embryogenesis and histological differentiation in T. pacific us were made for consideration of the developmental mode of the Oegops ida, which is a specialized group with a reduced external yolk sac. It appears that differentiation of the respiratory and digestive organs is relatively delayed in the Oegopsida, with reduction of the yolk sac as well as the egg size. These characters could be related to a repro ductive strategy for paralarval dispersion in the open ocean.