Octopus is not a fish. Although they can live in water, they do not breathe through their gills. Moreover, all fish have spines, and octopuses belong to mollusks, and their whole bodies have no bones. In addition, fish use fins to swim. Without fins, it is difficult for them to move in water, and fish have upper and lower jaws. Octopus crawls under the water with suction cups, and octopus has no upper and lower jaws and its mouth is not obvious. So octopus is not a fish. Although octopuses are not fish, they can grow normally in water, and they have high IQ. They not only protect themselves by jet ink, but also are good at camouflage and escape.

Octopus is a creature living at the bottom of the ocean, and they usually mainly feed on crustaceans. Such as shrimp, crab, shell and so on. Besides these, they also eat some planktonic creatures. Octopus has a high IQ. When they eat shellfish, crabs and other foods, they will first break the shell of the food and then eat the meat inside.

Octopus prey mainly depends on their tentacles. They have eight tentacles, and there are many suckers on these tentacles, through which they will absorb prey to their mouths. If the prey breaks free, they will tightly contract their tentacles until the prey dies.