This shark is also called the cigar shark and luminous shark. It is a large-eyed predator that lives in deep tropical ocean waters worldwide, at depths of about 3500 m. This shark occurs in warm, oceanic waters worldwide, particularly near islands, and has been recorded from as deep as 3.7 km (2.3 mi). It migrates vertically up to 3 km (1.9 mi) every day, approaching the surface at dusk and descending with the dawn. Reaching only 42–56 cm (17–22 in) in length, the cookiecutter shark has a long, cylindrical body with a short, blunt snout, large eyes, two tiny spineless dorsal fins, and a large caudal fin.