Squid

Lore & Background

Squid are soft-bodied molluscs with a head and foot at one end of a long body, functionally anterior during movement. They have eight arms and two longer tentacles surrounding the mouth, each bearing suckers often stiffened with chitin and sometimes with denticles. The two tentacles are retractile and used to grab prey, while the arms hold and control it; the beak cuts food into suitable chunks. Squid are rapid swimmers using jet propulsion, expelling water from the mantle cavity through a funnel, and largely locate prey by sight. They can change color for camouflage and signaling, and some species are bioluminescent for counter-illumination or eject ink to distract predators.

Reader's Guide

Squid are significant as key open-water predators that occupy a similar role to teleost fish in size and behavior, and they play an important role in the marine food web. They are among the most intelligent invertebrates, with Humboldt squid observed hunting cooperatively. Squid have been used for human consumption in commercial fisheries in Japan, the Mediterranean, the southwestern Atlantic, the eastern Pacific, and elsewhere, and appear in cuisines worldwide as calamari. They have featured in literature since classical times, especially in tales of giant squid and sea monsters. Their evolutionary divergence from other cephalopods occurred during the Jurassic, with true squid emerging to prominence around 100 million years ago. Fossil remains are rare due to soft bodies, but discoveries from the Yezo Group in Japan have clarified their presence in the Late Cretaceous.

Did You Know?

• Squid have a small internal skeleton called a gladius or pen, made of chitin.
• Some squid species can 'fly' for short distances out of the water.
• The vampire squid is more closely related to octopus than to any squid.
• Squid beaks are extremely fragile and can be destroyed during rock preparation.