The Pygmy shark, Euprotomicrus bispinatus, the smallest of all the shark species, is a sleeper shark of the Dalatiidae family, the only member of the genus Euprotomicrus, found in subtropical and warm temperate oceans worldwide, from the surface to depths of 1.12 mi (1,800 m). Their length is up to about 10.63 in (27 cm) for females and about 8.66 in (22 cm) for males.
The pygmy shark has a large head and under-slung jaw, strangely shaped caudal fin, and a very small first dorsal fin set far back on the body. The shark has no spines in front of the dorsal fins. The shark is black with a slightly paler belly and white borders to the fins.
The lower body is luminescent, which is thought to help in disguising the fish’s dark silhouette from upward-looking predators below.
The shark undertakes vertical migrations from the lower levels of its depth range to the surface each night. They follow the deep-water crustaceans, squids, and bony fish which rise at the same time to feed on surface plankton in comparative safety.
Pygmy sharks are ovoviviparous and produce about 8 young in each litter.
Illustration by Dr Tony Ayling