HOW ANIMALS EAT. | 
the adhesive power of the tentacles, and probably also 
emit a fluid, which paralyzes the victim; the mouth, 
meanwhile, expands to an extraordinary size, and the creat- 
ure is soon ingulfed in the digestive bag. 
In the next stage, we find no tentacles, but the food is 
brought to the mouth by the flexible lobes of the body, 
commonly called “arms,” which are covered with hun- 
dreds of minute suckers; and if the prey, as an Oyster, is 
too large to be swallowed, the stomach protrudes, like a 
proboscis, and sucks it out of its shell. This is seen in the 
Star-fish (Fig. 207). 
A great advance is shown by the Sea-urchin, whose 
mouth is provided with five sharp teeth, set in as many 
jaws, and capable of being projected so as to grasp, as well 
as to masticate, its food. 
In Mollusks having a single shell, as the Snail, the chief 
organ of prehension is a strap- 
like tongue, covered with mi- 
nute recurved teeth, or spines, 
with which the animal rasps its — 
food, while the upper lip is arm- 
ed with a sharp, horny plate 
(Fig. 27). In many marine spe- 
cies, as the Whelk, the tongue is 
situated at the end of a retractile 
proboscis, or muscular tube. In 
the Cuttle-fish, we see the sudden 
development of an elaborate sys- 
tem of prehensile organs. Be- 
sides a spinous tongue, it has a 
pair of hard mandibles, resem- Fre. 15.—Suckers on the Tentacles 
. ; of a Cuttle-fish: a, hollow axis of 
bling the beak of a Parrot, and the arm, containing nerve and ar- 
ror Torta = tery; ¢, cellular tissue; d, radiat- 
wo king a tically ? and around ing fibres; A, raised margin of the 
the mouth are eight or ten pow- ‘isk around the aperture 7 9, 
P F which contains a retractile mem- 
erful arms furnished with numer- _ brane, or “piston,” 
