ANIMALS WITH SPINY SKINS— THE ECHINODERMS 297 



drying the sea cucumber for shipment to China and other far eastern 

 countries for this purpose. When sold for human consumption they are 

 called beche-de-mer (worm of the sea). Most of us would probably be 

 more likely to eat them if they were called sea cucumbers. 



They have a very interesting method of protecting themselves from 

 enemies. Since their skin is not hard like that of the other echinoderms 

 they are more liable to injury, but have adopted another method of pro- 

 tection that is very effective. Inside the body is an extensively branched 

 respiratory tree which helps to remove oxygen from water which is 

 sucked into the anus for this purpose. When attacked by an aggressive 



Photo by Winchester 



Fig. 20.7. A sea cucumber. The resemblance to the familiar vegetable from which it 

 gets its name is quite evident in this photograph. The small structures coming out of 



the body are tube feet. 



enemy, such as a large crab, these respiratory organs may be thrown out 

 through the anus forming a tangled mass of threads which ensnares the 

 crab's legs and pinchers while the sea cucumber leisurely crawls away 

 and regenerates another set of organs. 



Sea Lilies — Crinoidea 



The name of this class means lily-like and members of this class 

 are commonly called the sea lilies. Most of the animals in this class 

 have a stalk which is attached to a rock or similar underwater structure 

 and five arms with branches coming out around the mouth. The sea 

 lilies are very abundant animals, but not as well known as the other 

 echinoderms because many of them inhabit the deep regions of the 

 seas where human beings cannot venture except with specially built 

 devices that can withstand the great pressure of the water. In these 



