The Starfish is one of the most curious creatures in the sea.

    The Starfish is one of the most curious creatures in the sea. It is called an " Echinoderm", which means it is spiny-skinned. In the middle of their bodies on both the top and bottom, are button-shaped disks. Through these disks they draw in or expel sea water. The disks on the underside act as mouths. Their eyes are at the tips of their arms and are protected by a circle of spines. Along the underside of their arms are grooves, and along these are arranged little tubelike sucker feet. These are used both for moving about and as organs of smell.

    One amazing thing Starfish can do is open an Oyster. They do this by attaching their sucking disks to either half of the oyster shell and pulling until the shell eventually opens.

    Coelenterata are a group of small animals including sea anemones and corals. Most of them live in the sea and have arms covered with stinging cells. They feed on plankton.

    海星是海洋中最古怪的動(dòng)物之一。它是一種棘皮類動(dòng)物，身上皮膚長滿刺。在它們身體的中間，上下都有紐扣狀的吸盤。它們通過這些吸盤吸水排水。內(nèi)側(cè)的吸盤是嘴。它們的眼睛位于手臂的頂端，被一圈骨刺保護(hù)著。沿著手臂內(nèi)側(cè)長有一些凹槽，里面長有吸管狀的吸足。這些是吸足既可以用來移動(dòng)，也是嗅覺器官。

    奇特的是海星能夠打開牡蠣。它們把吸足貼到牡蠣的兩片殼上，用力的拉，直到打開為止。

    腔腸動(dòng)物體型都比較小，包括海葵和珊瑚蟲。它們中的大多數(shù)生活在海洋中，手臂上鋪蓋著蟄刺細(xì)胞，以浮游生物為食。