The eight headed fish is the octopus. Octopus, also known as octopus, English name is Octopus.
It is a kind of mollusk, which is evolved from the Neopoda mollusk. The body is generally very small, with eight slender and long tentacles, hence it is also known as the "octopus".
Octopuses, like the familiar cuttlefish, are not fish, they all belong to mollusks.
What sets octopuses apart is that they have eight legs that are as long as ribbons and float in the water in a zigzag manner, hence they are also referred to as "octopuses".
八爪鱼=章鱼（Octopus）
For temperate molluscs,
living under water,
the suitable water temperature can not be lower than 7 ℃, the specific gravity of seawater is 1.021, and the environment with low salinity will die. Can feed on macrozoa and grow up.
It is widely distributed in tropical and temperate seas of the world's oceans.
（为温带性软体动物，生活在水下，适应水温不能低于7℃，海水比重1.021最为适宜，低盐度的环境会死亡。能摄食大型动物性浮游生物而成长。广泛分布于世界各大洋的热带及温带海域。）
