The Octopus breathes by means of gills. Water enters through a big hole
under the head, passes over the gills, and out again through a _funnel_,
or _siphon_. Now the Octopus can make good use of this siphon. Sometimes
he is attacked, and wishes to "make himself scarce." So he sends the
water rapidly through the siphon; the force is enough to jerk him
quickly backwards, his "arms" trailing behind.

The Octopus and his relations have another dodge as well. They possess a
bag of inky fluid. By mixing this ink with the spurt of water from the
funnel, the Octopus leaves a thick cloud behind him. The enemy is lost
in this dark cloud, while the Octopus darts safely away.

[Illustration: THE OCTOPUS--A MONSTER OF THE DEEP]

Having no armour to protect him, and no shelly home like that of the
snail, the Octopus is an easy prey to large fish, Seals and Whales. So
this trick of shooting backwards, hidden in a cloud of ink, must be of
great use. Soldiers and sailors use clouds of smoke to baffle their
enemy in battle. The Octopus uses clouds of ink.

Sharks, Conger Eels, and Whales are able to fight the Octopus and eat
his soft body; but small fish and Crabs keep away from the ogre if they
can. This is not easy, for he hides away under rocks, watching with his
great eyes for passing prey. If anything comes near enough, out flicks a
long, tapering, snaky arm, and holds the victim tight.

Down the inside of each arm are nearly three hundred round suckers. Each
one acts like those leather suckers with which boys sometimes play. Once
fixed, it is nearly impossible to unloose them, without chopping or
tearing the arm to pieces. First one and then another sucker takes hold,