| Main Sections: Physiology |
Physiology Squids are invertebrates, meaning they have no backbone, and they are also mollusks, meaning they have shells. The squid has adapted to having its shell on the inside of its body. A squid has a cigar-shaped body with two fins on either side that keep the squid balanced and aid in swimming. Like the octopus and other cephalopods, the squid has the ability to change color. It can go from orange to red to brown and from blue to green. It also can make itself almost transparent when it is in open ocean waters. Squids range in size from 8 inches (20 centimeters) to 56 feet (17 meters) and weigh up to three tons. Squid have 10 arms, two of which are tentacles with flattened ends covered with suckers. Suckers are also line the underside of the arms. Like all cephalopods, squids have well-defined eyes. But, a squid's eye is more well-defined than all the other invertebrates, with complete corneas, lenses, and retinas. Habitat Squids are found in all the world's oceans. The larger varieties are found in the North Atlantic and a little in the Arctic. Most species live in the open ocean at different depths. It is rumored that a giant squid, over 100 feet long, lives in the deeps of the Atlantic Ocean. There are some squids that live close to shore like the North American Squid, which is commonly eaten by humans. Diet Squids eat a large variety of fish and invertebrates. They capture the fish with their tentacles. Squids live and hunt in groups called schools. These schools have been known to follow schools of fish on which they feed on. In pursuing their prey a squid can reach a top speed of 23 miles per hour (20 knots). Predators Squids are hunted by many creatures, such as dolphins, sea lions, and sharks. Sperm whales are notorious for eating giant squid. Humans also eat squids on occasions. Japan alone catches 650,000 tons of squid in one year. In north America 700,000 tons of squid are caught in the fishermens' nets. The squid is either eaten or used as fish bait. To escape predators the squid uses basically the same methods as the octopus. Squids can change color to blend in with the environment, or they shoot out ink which temporarily blinds the predator, allowing the squid to use its miraculous speed to escape. Reproduction Squid reproduce in large spawning groups that can number in millions. They gather from November to April off the coast of California and other coast lines through out the world. After mating the female travels to the bottom of the ocean and lays 10 to 50 egg strings. These egg strings may contain hundreds of eggs. The egg strings are attached to the bottom of the ocean and left alone by the female. After breeding the adult squids leave the spawning site and soon dies. After 10 days the eggs hatch into miniature squids. A squid can live 1 to 3 years before it becomes sexually mature and dies.
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