A flattened ambush fish with a lacy iris flap that hides the pupil.
A platycephalid to about 50 cm, the head broad and flattened almost to the horizontal and the body tapering behind it, mottled in browns, greens and cream to match rubble. It lies motionless on the bottom, and at a metre it is a piece of the substrate with two eyes in it.
Those eyes are the feature worth a close look. The iris carries a branched, lacy flap — an iris lappet — that hangs down over the pupil and breaks up its outline, so that the one part of an ambush predator that cannot be camouflaged is camouflaged anyway. The lappet expands and contracts with the light. It hunts by lying still and taking small fish that pass within reach, and it will hold position while a diver settles beside it, which makes it one of the more accommodating subjects on a muck site. Recorded from the shallows to about 30 m. The photograph is the eye, and it needs light coming from in front rather than above.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.