Body slender, compressed; ridge over eye expanded at rear; tongue tip in 2 lobes;slightly oblique, top jaw reaches under middle of eye; shoulder girdle before base of pectoral fin with 1 (rarely 2) skin flaps; dorsal fin V (IV-VI) + I, 15-17 rays; anal fin I, 14-16 rays; pelvics form a cup, inserted under base of pectoral fin; scales very small, smooth, imbedded in skin, absent on head, nape, throat and base of pectoral.
Light tan; under head with black stripe; bright white patches at upper corner of mouth and chin tip; sides of body peppered with fine dark dots: an iridescent blue-black blotch on gill cover; anal fin with central broad black stripe; dorsal fins red-brown with white margin, each ray with black dots that form several stripes; tail fin rust colored above and below, with grey center and white margin, and about 5 wavy brown bars in center; lower rays of pectoral fin and edges of median fins bright white.
Size: reaches 6.4 cm.
Habitat: intertidal sand bottoms in bays and estuaries.
Depth: 0-7 m.
Northern California to Baja and the western and northeastern Gulf of California.