Coelacanth

The coelacanths constitute a rare order of fish that includes two extant species in the genus Latimeria: the West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis). This species was rediscovered in 1938. Coelacanths belong to the subclass Actinistia, a group of lobed-finned fish related to lungfish and certain extinct Devonian fish such as osteolepiforms, porolepiforms, rhizodonts, and Panderichthys.

They follow the oldest known living lineage of Sarcopterygii (lobe-finned fish and tetrapods), which means they are more closely related to lungfish, reptiles and mammals than to the common ray-finned fishes.

They average 5 feet (1.5 metres) in length and weigh about 100 pounds (45 kg). They are live-bearers that give birth to well-developed young. Though once thought to be deep-water fishes, coelacanths are now known to inhabit mesopelagic waters, below the continental shelf, at some 650–1,300 feet

During the daytime, coelacanths rest in caves anywhere from 100 to 500 meters deep while others migrate to deeper waters. By resting in cooler waters (below 120 meters) during the daytime, coelacanths reduce metabolic costs. 

The current coelacanth range remains primarily around the eastern African coast, although the Latimeria menadoensis was discovered off the coast of Indonesia. Coelacanths have been found in the waters of Kenya, Tanzania, Mozambique, South Africa, Madagascar, Comoros, and Indonesia.