The cuttles employ these suckers for two purposes. In the first place, they use them in walking. When a cuttle is crawling along at the bottom of the sea it pushes one or two tentacles forward, takes firm hold of a rock or a large stone with the suckers underneath them, pulls up the body, and then thrusts them forward again. And in the second place, they use them in catching their prey. Quite large victims are often seized by cuttles, and when once the deadly suckers have fastened upon them there is no hope of escape. In spite of their struggles one tentacle after another comes closing in, till they are completely surrounded by the long, slimy arms, soft almost as jelly, yet strong as steel. Then they are pushed down against the sharp, strong beak, by which they are quickly torn in pieces.
On the upper part of the head of the cuttle there is another curious organ known as the siphon, which consists of two tubes lying side by side together, like the barrels of a double-barreled gun. This organ is used in three different ways.
First, it is used in breathing. The cuttles, like the fishes, breathe water, by means of gills. These gills lie inside the head, and the water passes down to them through one of the siphon-tubes, and then out again through the other.
Next, it is used in swimming. When cuttles are not in a hurry they crawl along by means of their long tentacles, as we told you just now. But if they are startled, or alarmed in any way, they fold all their tentacles together in a straight line, fill both the siphon-tubes with water, and then squirt it out again as hard as they possibly can. The result is, of course, that they are driven rapidly backward by the recoil, just like the dragonfly grub, of which we have read.
But the third use of the siphon-tubes is the most curious. If you discover a small cuttle hiding in a rock-pool, you will very likely find that the water all round it suddenly grows dark as night, just as if a quantity of ink had been poured into it. The fact is this. Inside its body the cuttle has a bag filled with a quantity of a deep-black liquid called sepia. This bag is surrounded by strong bands of muscle, and opens into the siphon-tubes. So, you see, when the animal suddenly contracts the muscular bands, the sepia is squirted out through the siphon into the water, which is immediately darkened for some little distance all round. And under cover of the darkness the animal escapes.
The eggs of the cuttle are laid in a very curious way, for they are fastened by little stalks to a stem of seaweed, so that they look very much like a bunch of grapes. Fishermen, indeed, nearly always speak of them as "sea-grapes."
The cuttles which are found in the British seas are always quite small. But in some parts of the ocean these creatures grow to a giant size. Fragments of the tentacles of an enormous cuttle, for instance, have been found lying on the coast of Newfoundland; and by careful calculation it was shown that if the animal to which they belonged had stretched them out at right angles to its body, they would actually have measured more than eighty feet from tip to tip!
These huge creatures seem to form the principal food of the spermaceti-whale.
The Chambered Nautilus
This animal is a near relation of the cuttles. It lives in a shell, which cannot increase in size. The mollusk itself grows, however, and soon becomes too big to live in its home; so it forms a second and larger compartment outside the first one. Time after time this happens, till at last the shell consists of about thirty-six chambers, only the outside one being inhabited by the nautilus.