344 



Descriptive Zoology. 



the tube feet. Sometimes the radial symmetry is more 

 or less altered, for some of these forms so habitually rest, 

 or creep, on one side that they are said to have a dorsal 

 and a ventral surface. A sea cucumber may be compared 

 to a sea urchin that has been drawn out in the direction 

 of the poles that is, from mouth to anus and further 

 to have lost most of the ossicles in the body wall so that 

 it is now flexible instead of being rigid. There are many 



Tube feet 



Tentacles 



FIG. 193. SEA CUCUMBER. 



microscopic spicules in the integument that give it rough- 

 ness and sometimes some degree of stiffness. Various 

 forms of holothurians are found along the Atlantic coast. 

 Some of the holothurians are so extremely elongated that 

 they are frequently mistaken for worms. Among the 

 Chinese and other West Pacific peoples, sea cucumbers, 

 under the name trepang, are variously prepared for food. 

 They are used principally for soups, and are considered 

 a great delicacy. 



