66 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



surface, which projects above the water, a raised parti-colored 

 crest, and on its under surface a tangle of various appendages, 

 some thread-like and others in grape-like clusters of little 

 bell- or pear-shaped bodies. Each of these parts is a peculiarly 

 modified polyp- or medusa-zooid, produced from budding 

 from an original central zooid. Many other kinds of colonial 

 jelly-fishes occur which show similar differences among the 

 different members of the colony. Some individuals enable 

 it to move through the water, some protect the colony, others 

 procure or digest food and still others are modified into re- 

 productive organs. The whole colony, or compound animal, 

 floats or swims at the surface of the water and performs all 

 the necessary functions of life as a single animal composed of 

 organs might. 



Most of the common large jelly-fishes belong to a second 

 group (class Scyphozoa: Gr. skyphos, cup; zoon, animal). They 

 often occur in great numbers on the surface of the ocean. 

 Others live in deeper waters, a few having been dredged up 

 from depths of even a mile below the surface. The umbrella- 

 shaped bodies vary in size from less than an inch to more than 

 six feet in diameter. From the underside of the central part 

 of the body hangs a mass of long tentacles which are provided 

 with stinging-threads. The small animals that become en- 

 tangled in these tentacles, which sometimes reach a length 

 of more than 100 feet, are stung by the stinging-threads and 

 serve as food for the jelly-fish. The body substance of some 

 jelly-fishes is more than 99 per cent, sea-water. Most of 

 them are nearly transparent, but some are beautifully colored 

 and many are phosphorescent. 



Sea-anemones and Corals. The most familiar examples of 

 the polyps and jelly-fish branch of animals are the multi- 

 colored sea-flowers, or sea-anemones, found along all ocean 

 shores. The petal-like tentacles, that surround the central 

 mouth-opening spread wide and seize and thrust into the 

 mouth any small animals that may walk or swim into this 

 living trap. Less common are the beautiful sea-pens, sea- 

 feathers and sea-fans which are closely related to the sea- 



