Body slender, can be inflated; head wide and blunt; eyes large; nasal organ a short tube with 2 openings; teeth fused into a strong, parrot-like beak that lacks a front groove, large, opens widely at front; gill opening a vertical slit before pectoral base; pectorals large; fins without spines; no pelvic fins; dorsal fin high and round, 12-13 rays; anal 10-12 rays; pectoral angular, 20-22 rays; body and head covered with numerous short (< eye), fixed, 3-4 rooted spines that are triangular and flattened in cross-section, and, in some cases reduced to plates under skin, no spines on tail base; ~ 15 spines between snout and dorsal fin; pelagic juveniles with fleshy tentacle at base of each spine; tail fin with 9 rays.
Dark brown to grey-brown above, shading to white below; base of each spine on back in white spot, on sides in a yellow spot, on belly in a black spot, spots ~ pupil size; spines yellow; fins dusky, without spots; pelagic juveniles- eye-size black spots scattered over body.
