The smalleye pygmy shark (Squaliolus aliae) is a little-known species of dogfish shark in the family Dalatiidae, found in water 150–2,000 m (490–6,560 ft) deep near Japan, the Philippines, and Australia. It migrates vertically daily, spending the day in deep water and the night in shallower water. One of the smallest shark species, the smalleye pygmy shark is known to reach only 22 cm (8.7 in) long. It has a blackish, spindle-shaped body with relative small eyes, and a spine preceding the first dorsal fin but not the second. There are bioluminescent photophores on its underside, which may serve to disguise its silhouette from predators.