The New Student's Reference Work/Cuttlefish

Cuttlefish, one of the mollusks, with a head surrounded by eight or ten arms, provided with cup-like suckers. Two of these arms are longer than the others, are enlarged on the ends and are called antennæ. They are related to the chambered nautilus, squid, etc. They have no shell externally, but underneath the skin of the back is found a limy structure called cuttlefish bone. It is often seen in bird-cages. The eyes are large and prominent, and there is a pair of horny jaws in the midst of the cluster of arms. The body is elliptical in outline, and has fins running along each side. It is surrounded by a mantle that also incloses a cavity for the gills, which are two in number. There is a funnel-like tube opening into the mantle-cavity, and the animal can, by contracting muscles, cause the mantle-cavity to close and then throw water out through the funnel or siphon in jets. It can swim forward by the use of the fins, and backward by throwing jets of water through the siphon. These animals also possess a bag of inky fluid, some of which can be thrown into the water when they become alarmed, and thus conceal their position while they swim away. Sepia and India ink were manufactured from this ink of the cuttlefish. They are carnivorous and seize their prey by means of their arms. The common squid of the Atlantic coast is closely related. It is commonly used for bait by the fishermen. The octopus or devilfish also is a near relative. See Octopus.