Cephalopod Habits

Most are wrapped in a membrane, which is transparent (octopus, calamari) or opaque (squid). Only octopuses have the habit of protecting eggs; the female octopus secretes a shell to protect the eggs. Unlike other molluscs, cephalopods have a large amount of yolk, and cleavage occurs only at one end of the egg.

The embryos of Sepia, Loligo, and Octopus have yolk sacs. The octopus eggs hatch in about 50 days and the squid eggs in about 40 days. They develop directly (larvae resemble adults) or go through a larval stage of floating life. The eggs of Octopus briareus are large, and the hatched larvae resemble adults and live on the bottom of the habitat; while the eggs of O. vulgaris are small and the larvae need to live for several weeks to float.

O. joubini and sepioidea (Sepioteuthis sepioidea) raised in the aquarium mature and lay eggs in about 5 months. The lifespan of small species along the coast is estimated to be no more than 1 year, or even 2 to 3 years. Cephalopods are mostly carnivorous and feed on crustaceans and small fish. The adult calamari of the genus Illex feeds on juvenile mackerel, and the adult of mackerel feeds on the juvenile of the genus Illex. Calamari are cannibalistic.

Octopus mainly feeds on bivalve and decapod crustaceans. Nautilus often gather in groups, and groups of octopus and squid are also reported. Squid breeds in shallow waters in spring and summer. Squid also sees similar migration.