A squid is a mollusc characterized by an elongated soft body, large eyes, eight arms, and two tentacles. They belong to the orders Myopsida, Oegopsida, and Bathyteuthida but may be broadly categorized. As cephalopods, they have distinct heads, bilateral symmetry, and a mantle, with a small internal skeleton known as a gladius made of chitin.
Squid diverged from other cephalopods during the Jurassic period and serve as open water predators. They are important to the marine food web, using their tentacles to catch prey and their beaks to break it down. Squids are fast swimmers, utilizing jet propulsion and good vision to locate food. They exhibit high intelligence, with some species observed hunting cooperatively. Natural predators include sharks, sea birds, seals, and sperm whales.
Squid can change color for camouflage and signaling, with some species being bioluminescent or capable of ejecting ink to evade threats. They are commonly harvested for human consumption in various regions, including Japan and the Mediterranean.
