Octopus
Octopus 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.