Sea Anemones and Corals (Anthozoa Group)

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                                                              Animals  > No Backbone (Invertebrate) > Sea Anemones and Corals (Anthozoa)

Where They Live (Range and Habitat): Sea anemones and corals live in water (aquatic habitats). They are mostly found in shallow water along a coastline (near shore).  Water along the coast is saltwater (marine). Some types of corals and anemones are found in freshwater. Freshwater places can be lakes, streams and wetlands.

What Their Body is Like (Anatomy): As adults, sea anemones, corals and hydras have a body shape with their mouth facing upward and their body beneath it and stuck (anchored) to the ground. This type of body shape is called a polyp. The mouth is surrounded by tentacles, which can sting prey and pull them into their mouth. Inside the body, the prey is digested.

In anemones, the stinging cells in the tentacles work with a little spring that is coiled and ready to pop out when they are touched by prey swimming by. The stinging cells have a toxin that stops prey from moving (paralyzes).

In coral, the coiled cells can be sticky threads that catch small prey or floating matter and pull it in to the mouth.

How They Act (Behavior): When threatened, sea anemones and corals may use their stinging cells to repel predators.

What They Eat (Diet): Sea anemones and corals are carnivores. They capture prey as it drifts through their tentacles. Any touch triggers the stinging cells that will paralyze prey. Then the tentacles pull it into the mouth and down into its body where it is digested. Waste is then spit out through the mouth with a sharp squeeze of the body.

Sea anemones stay as polyps their whole lives stuck to the sea floor. When they hatch from their eggs, they are at first free-swimming larvae. Then they will attach to the sea floor and develop into the adult polyps. Sea anemones can also "bud" –  which means they grow small versions of themselves that, when large enough, break away and live independently. They are exact genetic copies of the parent.

Corals have many forms. Most form little cup-shaped skeletons where the coral polyp can pull inside for shelter. These are called stony corals. Corals form the base on which coral reefs grow.

Corals live with an algae in its tissues. It’s called zooxanthellae. The algae feeds the coral and gives it oxygen while taking up the carbon dioxide it doesn’t need. The algae are what give coral its many pretty colors, but they are very sensitive to pollution or water temperature changes. If they die, the coral loses its pretty colors. This is called coral bleaching. It is a sign of an unhealthy coral reef.

Coral is also killed by people collecting them to sell. Tourists snorkeling on the reefs sometimes walk on the fragile plants and animals. Boaters pollute the water. Coral reefs are important so we need to protect them.

To color sea anemones and coral: LINK
To learn more about sea anemones: LINK