Most marine organisms swim by pushing water behind them. This can be done with a variety of body structures, including fins, tails, and jets. Some marine organisms, such as jellyfish, swim by contracting their bodies.

The number of limbs that a marine organism has does not necessarily determine how it swims. For example, some fish have only two limbs, but they can swim very well by using their fins. Other marine organisms, such as squid, have eight limbs, but they swim by using their jets.

Here are some examples of how different marine organisms swim:

* Fish: Fish swim by using their fins to push water behind them. They can also use their tails to help them swim.

* Dolphins and whales: Dolphins and whales swim by using their tails to push water behind them. They can also use their flippers to help them swim.

* Jellyfish: Jellyfish swim by contracting their bodies. This creates a jet of water that propels them forward.

* Squid: Squid swim by using their jets. They can also use their arms to help them swim.

* Sea turtles: Sea turtles swim by using their flippers to push water behind them. They can also use their shells to help them swim.