Marine fish with cartilaginous skeleton. Thin, fusiform body; Relatively large eye. Snout relatively short, broad, not very pointed. Nasal openings on the sides of the muzzle. Teeth long, narrow, not sawn, relatively straight; 5 long gill opening, all in front of the breastplate. Origin of the first dorsal fin behind the breastplate. Second dorsal fin and anal very small, origin of the anal under the final part of the base of the second dorsal. Pectorals very long, of the same length as the head, tail almost symmetrical, semilunar. Base of the tail flattened, with a large keel that extends over the tail: Deep blue back and sides, white stomach, dark color under the muzzle and mouth. It measures up to 4.27 m.