HOW STAR-FISH WALK. 
85 
pet against the glass on his road you will see a curious 
sight. He will glide gently over it as though it were 
a mere stone, till his mouth is just above it, then the 
middle of the body will rise a little, and the feet all 
round the mouth fixing themselves firmly to the 
mussel will draw it into the opening, where it will 
remain till all its soft body is sucked out, and then 
the empty shell will return. 
If, however, the shell-fish is too large to go into 
the mouth, the star-fish will apply its lips to it and 
often push its stomach-bag (S, Fig. 37) out at the 
opening and half cover its victim, and after a time 
when it draws back, the soft animal will be gone and 
only the shell remain. 
Fig. 37. 
Section of the centre and one ray of a Star-fish. — Rytner /ones. 
A, The central body. S, The stomach, m, The mouth, k, Per- 
forated hole where water is taken in. r, Ring round the centre through 
which the water passes to the feet. B, The ray. sp, Spines set in the 
leathery coat, c, The snapping claws. <?, Eye at end of the ray. 1 1, 
Tube feet, v v, Vesicles or waterbags supplying the tube feet with 
water, *, Liver. 
The star-fish then is a kind of walking stomach, 
borne along by hundreds of tiny feet ceaselessly 
moving in each of its five rays, and it is the working 
of these feet which we must now explain. To picture 
to yourself the inside of a star-fish, imagine a round 
central dome -covered hall (A, Fig. 37"), in the floor 
7 
