296 ANIMALS WITH SPINY SKINS— THE ECHINODERMS 



The sand dollars are little disc-shaped echinoderms that have a tradi- 

 tional star-shape outlined on both the oral and aboral surfaces. A dried 

 one lying on the sand on the beach could be mistaken at a distance for 

 a silver dollar. 



Sea Cucumbers — Holothurioidea 



These are the sea cucumbers which are found along the bottom of the 

 sea in shallow water in tropical regions. They do resemble the cucum- 

 ber in appearance and differ from the other members of this phylum in 



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Photo by Winchester 



Fig. 20.6. Sand dollars. These disc-shaped echinoderms are often washed up on the 



sand of the beach. 



having a flexible outer skin that feels more like a piece of soft leather 

 than the hard spiny skin of the starfish. A number of tentacles come out 

 around the mouth which are waved in the water until sufficient food par- 

 ticles adhere to them ; then they are turned down into the mouth, the 

 mouth is closed, and the tentacles are withdrawn sucking the food off, 

 very much like a child would stick his fingers in a can of molasses and 

 then suck them. In oriental countries they are in great demand for soup 

 making, and a great industry in the Philippines consists of collecting and 



