Is an octopus a fish, a social animal

No, octopus, like fish, live in water, and their name also carries "fish", but they are not real fish, but mollusks. Fish must meet the following four conditions: first, they have a spine; Second, there are fins, and you can swim with fins; Third, there are upper jaw and lower jaw; Fourth, have gills and breathe with gills. However, octopus does not meet these four conditions, so it can be seen that they do not belong to fish. 1、 Is octopus a fish? Like the surrounding fish, octopus live in water, and their name also has the word "fish", so many people will think octopus is also a fish. In fact, octopus is not a fish, but a kind of mollusc. The difference between mollusks and fish is relatively large and can not be confused. Generally speaking, fish have four prominent characteristics: first, the spine is a necessary part; Second, fish have fins and can swim with them; Third, fish have upper jaw and lower jaw; Fourth, fish have gills and need to breathe with gills. However, octopus does not have these four characteristics, so it can be seen that they are not fish. 2、 Is octopus a social animal? A social animal refers to an animal that takes the collective as the unit when carrying out various activities, such as predation, sleep, migration and other activities. Octopus itself is a kind of marine organism with research value. Although they live in the same environment as fish, they belong to molluscs. In the process of studying their habits and characteristics, researchers found some Octopus nests underwater, in which many Octopus live. Therefore, it can be seen that octopus may also be a social animal. However, it is often seen that a single octopus is distributed on the seabed. They have high IQ, can change color, and have strong predatory ability. （ZhangYuShiYuMa，ShiQunJuDongWuMa）