A vocabulary of landscape — a landscape of words
1139 entries
cuttlefish
The cuttlefish is a mollusk related to squid and octopus, with eight arms, two long retractable tentacles for striking, and a W-shaped pupil. Its skin carries color cells it can expand and contract, layered over reflective cells beneath, so it can change color and pattern in a fraction of a second and run waves of moving stripe down its body while hunting. It is almost certainly colorblind, and how it matches colors it cannot see is not fully explained.
Etymology
The name is Old English cudele with fish attached later, which is the same thing that happened to shellfish, starfish, jellyfish, and crayfish. In every case English added fish to mean simply a thing that lives in the sea. The Latin name for the genus, Sepia, is the Greek word for the animal, and it became the name of the brown ink made from it, which is now the name of a color and of a photographic tone.
Notes
One proposal for the color problem is that the W-shaped pupil spreads light of different wavelengths across the retina at different focal depths, so the animal could read color from focus rather than from pigment. Male cuttlefish have been recorded displaying courtship colors on the side facing a female and a rival male’s pattern on the side facing a competitor at the same time.