The octopus is a member of the phylum Mollusca, the class Cephalopoda.

And amphibians and mammals belong to the same phylum Chordata! For temperate mollusks, living underwater, adapted to the water temperature can not be lower than 7 ℃, seawater specific gravity of 1.021 is most suitable, low salinity environment will die. Can ingest large animal plankton and growth. Widely distributed in the world's oceans of tropical and temperate waters.

Breeding:

Octopus in the ocean breeding time is generally concentrated in the spring and fall, spring and fall seawater temperature of about 16 ℃. Octopus like to spawn in conch shells, so the rope can be threaded through the red conch shells sunk to the bottom of the sea, extracted on time to catch. Autumn and winter often burrow in deeper waters in the sediment.

Octopus dioecious. The male has a specialized wrist, known as the stem wrist or copulatory wrist, which is used to place the sperm packet directly into the female's coat cavity.

Every breeding season, the female octopus lays eggs, about 0.3 centimeters long, totaling more than 100,000, under rocks or in caves. The female guards the eggs during incubation, using a suction cup to get the eggs clean and stirring them with water. The female octopus needs the young to hatch 4-8 weeks after the one-time egg laying. The juvenile octopus is shaped like an adult but small, and after hatching needs to drift with the plankton for a few weeks before sinking to the bottom to hide.