A slender cylindrical body; snout narrow, moderately long, pointed; eyes about midway between snout tip and gill slits; 5 gill slits; moderate sized spiracles just behind eyes; nasal flaps short, slender, not reaching mouth, with a minute or no secondary lobe, inner corners of nostrils closer to snout tip than to mouth; eyes without nictitating membrane; teeth low and blade-like, similar sized on both jaws, with strongly oblique tips; 2 dorsal fins with ungrooved spines (shorter spine on first dorsal), 2nd smaller than first; origin of the first behind pectorals; pectoral fin narrow, sickle-shaped, posterior margin slightly concave, inner posterior tip slightly rounded; no anal fin; tail base with a pair of keels and a strong pit above; tip of tail fin without a notch on underside, rear of tail with angular notch separating two lobes; skin with small, 3 pointed denticles.
Color: grey above, white below; usually conspicuous white spots or bars on sides; dorsal fin edges dusky in juveniles, plain in adults.
Intertidal to 1460m; from the surface to the bottom, usually near the bottom; often in bays and estuaries.
Antitropical; Pacific, Atlantic and Mediterranean, also SW Indian Ocean. From Alaska to the tip of Baja; also in Chile