Underwater reefs are covered with small mollusk shells, calcareous tubes, coral thickets. The waters are teeming with these small creatures of a very strange shape.

These are corals, sea anemones, sponges. They are direct descendants of the most ancient living creatures that appeared on Earth. Billions of radiolarians live in the water - the smallest animals, consisting of only one cell and invisible to the naked eye. Their body is covered with a silicon skeleton similar to lace.

Jellyfish

These gelatinous umbrellas are called jellyfish. There are many types of them. Many of the jellyfish are dangerous because they can burn the skin if they are touched.

Cuttlefish

Among marine animals, you can find strange creatures with tentacles going straight from the head. These are cuttlefish, squid and octopus.

Five tentacles

The number of rays, or tentacles, in starfish is always a multiple of five. With rays they open shells and get mollusks hidden inside. The ancestors of starfish inhabited the Earth about 500 million years ago.

Colonies

Some of the simplest marine animals, such as sponges and corals, live in colonies: they are a single unit, united by an external skeleton - flexible or solid.

When the animals that make up the coral colony protrude slightly from the openings of their skeleton, they look like numerous white flowers.