74 STAR-FISHES, SEA-URCHINS, ETC. 



either drawn forward, or the object of its search 

 drawn to it. The system of vessels which supplies 

 the tubules with water, governing as it does the 

 walking apparatus of tube-feet, is known as the 

 ' ambulacral' sj'stem. The area, again, along which 

 the tube-feet (ambulacra) are placed has been 

 called the ambulacral zone, and the intermediate 

 spaces — ^the sides and backs of the arms — the inter- 

 ambulacral. On the back of the animal, a little 

 sub-central, and in the angle between two of the 

 arms, is a tumid little body, of a bright orange 

 color, called the ' madreporic tubercle,' through 

 which the sea-water gains access to the ambulacral 

 system of vessels. 



Star-fishes are voracious animals, and they have 

 a method of securing their food which is at once 

 novel, and, to say the least, effective. Seizing their 

 prey, which consists largely of shell-fish, they arch 

 themselves over it, turn their stomachs inside out, 

 so as completely to envelop the delicate morsel, and 

 then deliberately proceed to make a meal. On some 

 of our northern coasts the star-fish is the principal 

 enemy of the oyster and scallop, vast quantities of 

 the former being annually gobbled up by this five- 

 armed demon. According to the reports of fisher- 

 men the appearance of the star-fishes on the coast 

 is frequently dependent upon the earlier appearance 

 there of the scallop. Star-fishes are very tenacious 

 of life, and they will bear much injury without suc- 

 cumbing. Indeed, each individual ray, when torn 

 from the body, has the power of reproducing the 

 entire animal. 



