Cuttlefish
a well known mollusk with out an external shell. The cuttlefish is known to zoologists as a cephalopod. It is related to the squid and the octopus. The body is oval, but is somewhat flattened. A thin flap of skin like a frilled fin runs down each side. The animal has two prominent eyes. The mouth is surrounded by eight short arms and two long tentacles, or feelers. Each arm carries four rows of raised suckers. The two long arms, or tentacles, terminate in circular, saucer-shaped suckers. The cuttlefish uses these arms to attach itself to objects and to seize prey. The cuttlefish "walks" by laying hold of stones and other objects with its suckers and dragging the body about. By expelling water forcibly from a tube beneath the head, the animal is able to dart backward with unexpected rapidity.
The common cuttlefish of the British coast is a pest to fishermen. It ruins the fish in their nets and is difficult to catch. When alarmed the animal ejects an inky liquid which discolors the water for yards, and enables the cuttlefish to escape unseen. This liquid is the sepia ink of commerce, so indispensable to draftsmen. An internal shell at the back of the body is the cuttlefish bone fed canaries. It is also crushed to form a powder, called pounce, which was shaken on a newly written page to dry the ink before blotters were invented. Pounce is still used for tooth powder, and in the making of molds for silver castings. Clusters of cuttlefish eggs are cast ashore by the waves and are sometimes called sea grapes.
A very curious habit of the cuttlefish is the way it changes its color. This it can do at will. If it happens to find itself on a sandy bed, where the pebbles are variously colored, yellow and black, it can change its color so that it takes a keen eye to distinguish the animal from its surroundings. If it moves into a region where dark rocks abound, the little spots, specks, or stripes with which it was adorned a half-hour before disappear, and a dark, nearly black animal is seen. These sudden changes in color are brought about by means of large cells in the skin, which are filled with coloring matter; as these cells contract or expand, the color of the animal changes.