The statement that a shark keeps swimming because it doesn't have a swim bladder is true.

Sharks do not have swim bladders. Instead of being able to float up and down in the water like a normal fish, they have to keep swimming and in doing so control their bodies in the water.

1. When sharks swim, they rely mainly on their body and tail fins to swing forward, so most sharks can only move forward, not backward, and are therefore easily caught in human gill nets. Sharks do not have swim bladders, so their specific gravity is determined mainly by the amount of oil stored in their livers.?

2. Sharks live in the ocean, and different species have different diets. Whale sharks are oceanic fish, mainly feeding on plankton. Flathead Hanna sharks, narrow-grained tiger sharks and other species living on the sea floor, mainly feeding on shellfish, crustaceans and other benthic animals.

3, ferocious species generally live in the middle and upper layers of the ocean, to a variety of fish and other large marine animals for food, a few species can even attack people.

4, sharks do not have swim bladders, coupled with the fact that most sharks are relatively large in size, and the density of sharks is slightly greater than the water, do not actively swim, it will sink to the bottom of the sea. Therefore, in order to be able to ensure that they are always in a body of water, and thus get a sufficient amount of food, the sharks will have to swim non-stop all the time.