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Squid and Octopus


phytoplanktonSquid are mollusks like clams and oysters but they have no shells on the outside of their bodies! They have a shell inside their bodies called a pen.

There are about 375 species of squid. Squid have 10 arms. Two of their arms are longer than the other eight and are called tentacles. Squid range in size from under an inch to more than 60 feet in length! They have long, tubular bodies and little heads. Squid are very fast swimmers and use a kind of jet propulsion to move.

Squid suck water into a long tube called a siphon and then push it back out. They can aim the water in any direction. Squid have very good eyesight and may even be able to see in color. The squids' two tentacles are specially adapted for feeding and they use them to grab their prey. They have a sharp beak on their mouths that they use to break open shells.

Squid have some unique adaptations. Some can change color, some use bioluminescence to create light, and some shoot ink to cloud the water and lose predators. Squid usually travel in  groups and  can be found in the sunlit zone and the twilight zone.

phytoplanktonOctopus are mollusks like squid. There are about 200 species of octopus. There are two large groups of octopus. The cirrata or finned octopuses live in the deep sea at depths of between 1000 and 24,000 feet. About 85% of octopus are in the incirrata group. They have no fins and live in shallow water in caves or crevices.

Octopus have no shell at all, not even an inner one. They have eight tentacles. The tentacles have suction cups on them and are used to hold onto prey. The tentacles also have taste sensors that let the octopus know if what it grabbed is worth eating.  

The octopus' mouth is in the center of its tentacles. It has a sharp beak on its mouth that it uses to crack shells. Some species may also inject prey with a toxic substance. Because it has no shell, an octopus can squeeze into very small spaces. Octopus live alone and, like the squid, some species can shoot ink and change colors.



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