|Year of Publication:||2004|
|Keywords:||Cephalopod, color pattern changes, defense strategiesmollusks, marine invertebrates, mating behaviors, squid|
Squid are soft-bodied invertebrates known for their eight arms and two long feeding tentacles. They also have sharp, parrotlike beaks and three hearts--a central heart and two additional ones that pump blood through the gills. Squid and their relatives belong to a class of mollusks known as cephalopods, which includes the cuttlefish, octopus, and nautilus. Cephalopods are smart and agile, possessing sophisticated senses and the remarkable ability to instantly change the color pattern of their skin, enabling them to easily pounce on their prey or hide from their predators. These characteristics set squid and their kin apart from the average clam or oyster, also mollusks. Squid families include 280 species that range in size from tiny to monstrous and roam the oceans from Cape Cod to Venezuela to California. Some of these mollusks have a delicate beauty, while others look like sea monsters. Squid have the largest brains among all invertebrates, an indication of high intelligence. The ability to change skin color pattern allows squid to court mates, challenge rivals, and communicate with one another. A male Caribbean reef squid, for example, splits into two patterns during courtship; its coppery right side is oriented toward the female, and its silvery left side is used to ward off rival males. Most squid live for only a year or so and must reproduce quickly. Different species use different reproductive techniques. The female opalescent inshore squid uses mass production, laying more than 50,000 eggs in hundreds of fingerlike egg cases; the female Caribbean reef squid deposits only three or four eggs per case, which she carefully hides among stinging coral. One of the biggest squid species is the Humboldt, or jumbo, squid, which can grow up to 12 feet. Humboldts are fierce marine predators that will attack anything from sardines to scuba divers and even its own kind. When camouflage does not work, these aggressive squid usually spew ink as a defense strategy.