Sea Anemone Features
Sea anemones use their tentacles to catch food. The sting capsule or nematocyst, in the tentacles contains a coiled, hollow filament that is usually barbed and contains poison. When triggered by touch or chemical stimulus, the internal fluid pressure in the stinging cells increases rapidly and forces the thread-like filament to shoot out.
These barbed threads pierce the skin of the sea creature and inject poison. The anemone moves all the nearby tentacles around the creture to hold and sting it before moving the creature towards the mouth.
The victim is paralyzed by the stinging tentacles and dragged into the digestive cavity within the body. The creature is digested and absorbed, and any remains such as bones or shell are excreted through the mouth.
Sea anemones feed on plankton, crustaceans - like crabs, shrimps and prawns, mussels, worms and even sea urchins. They are generally not palatable to others but they are preyed upon by grey sea slugs and some fish such as the butterfly fish. The sea slugs are not immune to the anemone's sting but their digestive tracts do have a protective coating.
Sea anemones use their stinging tentacles for defence. They protect the anemone from being bitten or swallowed and are also used in territorial fights with other anemones. When two colonies come into contact, the touching anemones sting eachother repeatedly until one withdraws or dies. Eventually, a narrow strip of bare ground forms between the colonies and they can live in harmony.
Sea anemones often remain in the same place for days, weeks or even months. They live attached to firm objects in the sea such as the sea floor, rocks or coral but can move around in three different ways when they need to:
- by sliding or creeping around on their basal disc very slowly.
- by inflating, detaching and letting the currents and tides take them into a new location.
- by uprooting themselves and using a flexing motion to swim away.
Some sea anemones can even burrow. Most sea anemones seldom move around once they have found a suitable place to settle but if conditions become unfavourable, they will roll or be carried a considerable distance.