? Squid is not a fish. Although it is customarily called a fish, it is only a mollusk, belonging to the decapod order of mollusks. Although the squid lives in the water and breathes with its gills, it lacks fins and a spine. The body of a squid consists of a head, a neck, and a trunk. The squid has well-developed eyes and brachiopods on both sides of its head. Squid can be eaten and is a common delicacy on the table. Squid is rich in nutrients, such as phosphorus, calcium and other elements.
of fish? 1. Fish live in sea water or fresh water all their lives, have body shape and fins suitable for swimming, breathe with gills, and have a single blood circulation.
2. The body of the fish will be covered by fish scales, which can protect the fish from external objects damaging the skin. Look carefully, there will be a layer of mucus on the surface of the scale, which helps the fish save energy and reduce resistance when swimming. Slime also prevents fish from being injured in complex environments.
3. There is a swim bladder in the body of the fish. The swim bladder helps the fish to adjust the specific gravity of the body. Under the combined action of the swim bladder and the fin, the fish can stay in different water layers.
4. There is a line of lateral line on both sides of the fish's body. The lateral line is closely connected with the nerve, which can measure the direction and sense the running water.
