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’ system. 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. Onsome 
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. 
