FOOD TAKING AND NUTRITION 
171 
151. Locomotion. — Locomotion in the starfish is ac¬ 
complished by means of the four rows of tube feet which 
extend from the rays on the oral surface. The tube feet of 
the arms in front are attached to the surface over which the 
starfish wishes to move. Then the tube feet of the arms to 
the rear are released and the starfish draws up these arms, 
raising the disk region 
up. The tube feet in the 
arms to the rear are at¬ 
tached to the surface 
while the arms to the 
front are released and 
pushed ahead as the disk 
is lowered to the surface. 
This motion is carried on 
slowly until the starfish 
has reached its destina¬ 
tion. Each tube foot has 
an adhesive disk and is 
connected with a small 
reservoir inside of the 
arm. 
152. Food Taking and 
Nutrition. — The starfish 
takes its food in an un¬ 
usual manner. Most ani¬ 
mals move the food to 
Figure 160. — The Embryo of the 
Starfish. 
It develops into a free swimming larva 
that does not look at all like the parent. 
After a time the young starfish is formed. 
move 
the mouth, swallow it or engulf it, and digest it within the 
body cavity. In the case of the starfish we find that the 
stomach is projected through the mouth and made to sur¬ 
round its food. In this position it digests and assimilates 
the food and then withdraws its stomach through the mouth 
and moves on slowly to some other place. A common food 
of the starfish is the clam. Various explanations have been 
offered as to how the starfish is able to secure the soft flesh 
