What is plankton?

Plankton (浮游生物) is a mass of plants and animals that float near the surface of the ocean. Most plankton are very small. Many cannot be seen without a microscope.

Plankton plants make food by using energy from the sun. Plankton animals eat the plankton plants. Larger animals eat the plankton animals. This is called a food chain. Without the sun shining on plankton plants most ocean animals could not exist.

Do sharks have skeletons?

Most sharks are fast swimmers with razor-sharp teeth. Usually they eat ocean animals like crabs, fish, seals —— even other sharks.

Sharks do not have bones like other fish. Their skeleton is made of cartilage(软骨). This is the same bendable material that is in your ears and the tip of your nose. Some of these sharks have killed people but the number is very, very small. The biggest of all sharks are the whale sharks. They are not whales but they are named after whales because they are so big.

Other animals in the ocean

Although there are many other animals in the ocean they are not fish. These animals are dolphins, whales, seals and walruses. They are warm-blooded mammals like horses, dogs and human beings.

Most fish lay eggs but mammals do not. Mother mammals give birth to live young and feed their babies with milk.