300 Animal Biology 



Fig. 103. — Brittle star (oral view) of the phylum Echinodermata, class Ophiuro- 



idea. 



TUBE FEET 



Fig. 104. — Starfish from the oral or under side, showing the rows of tube feet 

 extending from the ambulacral grooves. The long, movable ambulacral spines 

 protect the tube feet when the latter are retracted within the groove. Similar 

 oral spines surround the mouth for protection. (From Parker and Clarke: An 

 Introduction to Animal Biology, The C. V. Mosby Co.) 



