Cuttlefish
2 of the 6 encyclopedias on this shelf carry an entry for Cuttlefish. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
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. See Squid ; Octopus
Collier's New Encyclopedia (1921)
a genus and family of cephalopodous mollusks of the order Dibranchiata. The body is oblong and depressed, sack-like, with two narrow lateral fins of similar substance with the mantle; the whole shell is light and porous. The eyes are very large, and the head is furnished with eight arms, each of which has four rows of suckers and two long tentacles expanded and furnished with suckers on one side at the extremity.
What Has Changed in the Last Century
Aiton's 1910 account of colour change through pigment cells that "contract or expand" was broadly right: those cells are chromatophores, now known to be pulled open by radial muscles under direct nerve control from the brain, which is why the change is near-instant. The twist nobody in 1910 or 1921 suspected is that cuttlefish are colour-blind, having a single visual pigment, yet still match coloured backgrounds — they are also sensitive to polarised light, which may be part of the answer. The sepia ink Aiton's called "so indispensable to draftsmen" was displaced by synthetic pigments, and pounce by blotting paper and then ballpoints, though cuttlebone is still sold for cage birds. Where both entries treat the animal as a fishermen's pest, cuttlefish are now a major commercial catch, especially in East Asia and the Mediterranean, and a standard laboratory animal in studies of camouflage and cognition.
Written for this edition, 2026.