Polyp - Classes

Classes

In the class Anthozoa, comprising the sea anemones and corals, the individual is always a polyp; in the class Hydrozoa, however, the individual may be either a polyp or a medusa, with most species undergoing a life cycle with both a polyp stage and a medusa stage. In class Scyphozoa, the medusa stage is dominant, and the polyp stage may or may not be present, depending on the family. In those scyphozoans that have the larval planula metamorphose into a polyp, the polyp, also called a "scyphistoma," grows until it develops a stack of plate-like medusae that pinch off and swim away in a process known as strobilation. Once strobilation is complete, the polyp may die, or regenerate itself to repeat the process again later. With Cubozoans, the planula settles onto a suitable surface, and develops into a polyp. The cubozoan polyp then eventually metamorphoses directly into a Medusa.

Famous quotes containing the word classes:

“When we of the so-called better classes are scared as men were never scared in history at material ugliness and hardship; when we put off marriage until our house can be artistic, and quake at the thought of having a child without a bank-account and doomed to manual labor, it is time for thinking men to protest against so unmanly and irreligious a state of opinion.”
—William James (1842–1910)

“Between richer and poorer classes in a free country a mutually respecting antagonism is much healthier than pity on the one hand and dependence on the other, as is, perhaps, the next best thing to fraternal feeling.”
—Charles Horton Cooley (1864–1929)

“What’s the greatest enemy of Christianity to-day? Frozen meat. In the past only members of the upper classes were thoroughly sceptical, despairing, negative. Why? Among other reasons, because they were the only people who could afford to eat too much meat. Now there’s cheap Canterbury lamb and Argentine chilled beef. Even the poor can afford to poison themselves into complete scepticism and despair.”
—Aldous Huxley (1894–1963)