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 w T ater, 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- 



