Most abundant animal type

Copepods are crustaceans and are found almost everywhere where water is available. They include over 12,000 species and, with krill, form the most important members of zooplankton. They form groups that can reach a trillion individuals. Most are very small, less than 1 mm (0.04 in) long, but some rare oceanic species are over 1 cm (0.4 in).  Copepods have colonised almost every habitat from 10,000 m (32,800 ft) down in the deep sea to lakes 5,000 m (16,400 ft) up in the Himalayas and from subzero polar waters to hot springs. They can even be found on land in damp moss and in subterranean habitats such as caves and groundwater. Over 200 families and 1,600 genera exist. They are the most plentful multicellular group on the planet, outnumbering insects (which include more species but less individuals). Zooplankton is the first link of the aquatic food chain, although not all of them feed on phytoplancton. Some are carnivorous (when large) and a few are parasites. They provide the basic diet for many whales, seals, fish, aquid and seabirds. Also, they are the only known animal with just one eye. SIZE=3<>