Krill

Krill, small marine animal (genus Euphausia) resembling shrimp. There are over 90 species, ranging from 3/8 in (1 cm) to nearly 6 in (15 cm). Krill live in the open sea at depths of more than 6,600 ft (2,000 m). Most species have special organs (photophores) that make them visible in the dark. At night they swim in swarms of thousands to the surface to feed on microorganisms. Krill are an important food source for birds, seals, and whales, especially blue and finback whales. Rich in vitamin A, krill have been considered as a possible human food source.