The spine on its forehead locks. The first dorsal spine hinges up into position and a second, much smaller spine slots in behind it and jams it there, so that raising it is reversible for the fish and not for anything pulling on it. Triggerfish are named for the same mechanism and filefish inherited it: the animal reverses into a hole in the coral, raises the spine against the roof, and becomes very difficult to extract.
It is solitary and secretive, never far from cover, and it comes in three quite different patterns: plain dark brown, mottled gray-brown, and gray covered in a fine net of polygons, which is where the name honeycomb comes from. All three carry a white spot at the base of the rear dorsal fin and blue lines across the head.
The young live somewhere else entirely, drifting in open water under mats of floating Sargassum, and settle onto a reef later.
The skin is the other family trait: dry, rough, covered in minute spinules. Dried filefish skin was once genuinely used as sandpaper.
The species. Cantherhines pardalis (Rüppell 1837) - like a leopard. ETYFish
- first dorsal spine locks upright, held by a smaller spine behind it
- white spot at the base of the rear dorsal fin
- blue lines across the head and a yellowish tail
- three color patterns: plain brown, mottled, or gray under a net of polygons
- up to 25 cm
