CORAL REEF SYSTEM.

Auckland Star, Volume LV, Issue 307, 27 December 1924, Page 5

CORAL REEF SYSTEM.

HARD WORK FOR TINY ANIMALS.

At the first glance the sea anemones i arc more flower-like than animal-like. These delicate, richly coloured organisms with their numerous tentacles have received names derived from; flowers—sea anemones, passion-flower ' anemones, crimson anemones, etc., are : names which characterise their outer appearance correctly, for they change! the naked rocks of the shore to flower ■ beds. But, says "Nature Magazine," of i Washington, the life of these animals is in no way flower-like. They are very voracious, catch young fish, worms,, crayfish, snails, etc., which are often i much larger than themselves. They have peculiar protective ability in their tentacles, which also serve to daze their P rey - These are stinging organs, tiny, microscopical, bottle-shaped glands filled with a burning alkaline fluid." When touched, hollow coiled threads suddenly project, dart toward the touching object with their tiny hooks, and press out the fluid of the capsule, which then enters j the wound. Such stinging glands are j very numerous on each tentacle; in fact, thousands being located in one. Sea anemones which have congregated in groups, and live in colonies and have excreted a more or less hard skeleton, whose branches have become calcareous, i are corals. Every coral branch or colony has its beginning in one individual which happened to attach itself to that par- j ticular place and grew up in the shape of a tiny sea anemone. Upon the under surface of the eylin- | drical body the animal secretes calcare-j ous plates which join it intimately to its support. Then the calcareous plates i grow upward radially, and the outer side of the animal is bounded by a,] skeleton of lime wliich grows higher: and higher, drawing the polyp before it,' Thus it happens that at the branches of a coral colony often thousands of animals continue to build upward, while the lower animals have long since died. In this way these delicate little animals build mighty reefs, and many tropical islands are built by unceasing and. Un- j tiring work. _ .. j