56 HYDY^, JELLYFISHES, SEA ANExMONES, CORAL POLYrS 



suspended, but is supported by numerous radial partitions 

 that extentl from it to the body walls. Between these are 

 other partitions that do not reach the gullet, one edge being 

 free (Fig. 25). The reproductive organs are attached to the 

 faces of these vertical partitions. The tentacles are hollow 

 and open directly into the body cavit)'. They are expanded 



by a contraction of the 

 body wall, which forces 

 the water contained in the 

 body cavity up into the 

 hollows of the tentacles, 

 thus causing them to ex- 

 tentl and enlarge. The 

 food is caught by the 

 tentacles and passed into 

 the mouth. The whole 

 body, when the animal 

 becomes alarmed, con- 



FiG. 25. — Diagram of a cross section of a tractS and shrinks Into a 

 sea anemone. ,. u i i ■ i 



shapeless mass, by aid 

 of its muscle fibers after the water is expelled. "^^Iien all 

 is quiet again, it slowly draws in water, and gradually 

 expands to its former size. 



Other sea anemones. — There are manj^ species of sea 

 anemones and they are of various sizes and colors. They 

 are abundant along the seacoast, and resemble flowers so 

 much that they are popularly known as "sea flowers." 

 Most sea anemones can detach themselves an<l move from 

 place to place. The tentacles are constantly but slowly 

 moving, and often, when stimulated by contact with foreign 

 substances, they attempt to carry the particles to the mouth 

 of the animal. 



