The market squid (Loligo opalescens) is a small cephalopod found in the Eastern Pacific Ocean. In the spring and fall, huge schools of the squid enter Monterey Bay to spawn. They lay large, communal egg masses on the sandy seafloor and then die.These spawning squid are targeted by fishermen who attract the animals to the surface with large lights. The market squid population supports an important fishery along the coast of California. 



Loligo opalescens is a useful organism for the study of developmental biology because it develops rapidly within large, clear eggs and can be easily observed. Market squid are direct developers and hatch out of their yolky eggs as a 'paralarva,' a miniaturized forms of the adult.