A broad, heavy cuttlefish reaching 43 cm (17 in) in the males, patterned in shifting zebra bars over a body edged by a continuous fin that ripples like a skirt. The pupil is a horizontal W, which is worth looking for: it is the field mark that separates a cuttlefish from every squid and octopus on the reef.
That eye is stranger than it looks. Cuttlefish have a single visual pigment and cannot see color in the way we do, yet they match colored backgrounds accurately. The leading explanation is that the odd pupil shape smears incoming light into its component colors, and the animal reads color from how far it has to focus - seeing hue through blur rather than through pigment.
Hunting is theater. Approaching a shrimp, the cuttlefish sends bands of dark pigment rolling forward along its body in waves while the arms are held in a stiff cone, and the prey stays put through what should be an obvious threat. Then two feeding tentacles fire out in about thirty milliseconds and pull it in.
Males fight over females with color, holding a display toward a rival on one side of the body while showing female patterning on the side facing the female - deception addressed to two audiences at once, on the same animal, in the same second. Females lay eggs in dark clusters under ledges and die shortly after. The whole life takes one to two years.
- horizontal W-shaped pupil
- a continuous fin running the whole length of the mantle, rippling like a skirt
- shifting zebra bars that roll forward along the body when hunting
- broad heavy body, males to 43 cm
Why it's threatened
Threat classification from the IUCN Red List.
