|A selection of sea anemones,|
painted by Giacomo Merculiano, 1893
Sea anemones are Cnidarian animals that live in the sea. They are polyps, one of the basic forms of the phylum. They are predatory animals, which paralyse their prey with stinging nematocysts which fire a harpoon-like structure which delivers a dose of neurotoxins. To eat the fish, or crustacean, they move the prey into their stomach, where they are slowly digested.
Anemones are sessile. This means they like to stay in one area. They can move very slowly along the bottom. Some types can swim to a new location by using flexing movements. Reasons to move might be for safety (attack by a predator) or being in a too dry environment.
An anemone has an oral disk on the top of its body. The sea anemone’s mouth and gut are in the middle of the oral disk. The tentacles surround the oral disk. The pedal disc is on the bottom of the sea anemone.
Some sea anemones live in symbiosis with other animals. Clownfish, Incognito goby, and Arrow crabs find shelter among the tentacles of the anemone. Hermit crabs often have sea anemones on the shell they inhabit. Some anemones have a symbiosis with a type of algae which lives inside them. This is the same thing many corals do. The dinoflagellate algae use sunlight to make food, and the anemone uses some of the food.