Latimeria is a rare genus of fish which contains the only living species of coelacanth. It includes two extant species: the West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis). They follow the oldest known living lineage of Sarcopterygii (lobe-finned fish and tetrapods), which means they are more closely related to lungfish and tetrapods (amphibians, reptiles and mammals) than to the common ray-finned fishes and cartilaginous fishes. They are found along the coastlines of the Indian Ocean and Indonesia. Since there are only two species of coelacanth and both are threatened, it is one of the most endangered genera of animals in the world. The West Indian Ocean coelacanth is a critically endangered species. Biological characteristics Based on growth rings in the creatures' ear bones (otoliths), scientists infer that individual coelacanths may live as long as 80 to 100 years. Coelacanths live as deep as 700 m (2300 ft) below sea level, but are more commonly found at depths of . Living examples of Latimeria chalumnae have a deep blue color which probably camouflages them from prey species; however, the Indonesian species (L. menadoensis) is brown. Coelacanth eyes are very sensitive, and have a tapetum lucidum. Coelacanths are almost never caught in the daytime, but have been caught at all phases of the moon. Coelacanth eyes have many rods, receptors in the retina that help animals see in dim light. Together, the rods and tapetum help the fish see better in dark water. Coelacanths are opportunistic feeders, hunting cuttlefish, squid, snipe eels, small sharks, and other fish found in their deep reef and volcanic slope habitats. Coelacanths are also known to swim head down, backwards or belly up to locate their prey, presumably using their rostral glands. Scientists suspect that one reason this fish has been so successful is that specimens are able to slow down their metabolisms at will, sinking into the less-inhabited depths and minimizing their nutritional requirements in a sort of hibernation mode. The coelacanths which live near Sodwana Bay, South Africa, rest in caves at depths of during daylight hours, but disperse and swim to depths as shallow as when hunting at night. The depth is not as important as their need for very dim light and, more importantly, for water which has a temperature of . They will rise or sink to find these conditions. The amount of oxygen their blood can