Octopus is not a fish.

The octopus is a mollusk, living underwater, the body is short ovoid, sac-like, no fins, the head and the carapace is not clearly demarcated, usually crawl with the wrist, inhabiting the rocky seabed in the caves or crevices, when in danger, it will be spewed out of the ink-like substance.

The octopus is widely distributed in the world's oceans of tropical and temperate waters, can feed on large animal plankton. Octopus is also known as octopus, octopus, octopus, sitting octopus, stone residence, dead cow, carnivorous, to valve gills and crustaceans for food. Octopus like to spawn in the shell, fall and winter often burrow in the deeper waters of the mud and sand, adapted to water temperatures higher than 7 ℃, seawater salinity low environment will die.

Octopus characteristics

Octopus body surface warts densely packed, skin pigment cells distributed throughout the body, can change with the surrounding environment, body color and body length, in the rocks and seaweed show good mimicry. The octopus crawls along the seabed with a sucker, but when frightened, it will eject water from the body tube, thus moving rapidly in the opposite direction. When in danger, it spews an ink-like substance that acts as a smokescreen, and some species produce a substance that can paralyze an attacker's sensory organs.

Octopus sensory organs of the most developed is the eye, the eye is not only very large, and open bulging, motionless, like an owl. The structure of the eye and very complex, in front of the cornea, surrounded by sclera, and a developed lens comparable to vertebrates.