Why do Gonatid Squid Berryteuthis magister Lose Tentacles on Maturation ?

Abstract

Bathymetric distribution, maturity condition, and food and feeding of the common gonatid squid Berryteuthis magister are described for the off-shore population in the Sea of Japan, based on specimens trawled on off-shore banks in May-June 1970. Its wide depth ranges over 200-1,200 m and extremely poor feeding are confirmed. Active reproduction at depths below 1,000 m by distinctly large specimens is conspicuous. Frequent occurrences of “eight-armed specimens” that have lost both tentacles are discussed with special reference to copulation as a primary factor responsible for this unusual phenomenon. Its possible significance is also considered. © 1993, The Japanese Society of Fisheries Science. All rights reserved.