Coelacanths

Coelacanths are a lineage of lobe-finned fishes in the order Coelacanthiformes, belonging to the family Latimeriidae. They are among the closest living relatives of the first animals to colonize land and are often described as living fossils. Two extant species are recognized: Latimeria chalumnae, found in the western Indian Ocean, and Latimeria menadoensis, described from Indonesian waters.

They inhabit deep, cool ocean waters on continental shelves, typically at depths of about 150 to 700 meters, sometimes deeper, where they shelter in caves or under ledges and ledges of underwater slopes. Their geographic ranges are disjunct: L. chalumnae along the eastern African coast and around Madagascar, and L. menadoensis in the region near Sulawesi.

Physiology and morphology: Coelacanths have robust bodies with distinctive lobed pectoral and pelvic fins that move in a limb-like fashion. They possess cosmoid scales, a hollow notochord, and a unique intracranial joint in the skull. A diphycercal tail, a fatty buoyancy organ, and a rostral organ in the snout (thought to aid in electroreception) are characteristic features. Their coloration and patterns help camouflage them in deep-water habitats.

Reproduction and biology: Coelacanths are ovoviviparous; eggs are fertilized internally and hatch inside the female, with a small number of large, well-developed young born after a lengthy gestation. They are slow-growing and long-lived, with lifespans estimated in decades.

Discovery and conservation: The living coelacanth was famously rediscovered in 1938 off South Africa, ending millennia of assumed extinction. A second species was described in 1999 from Indonesian waters. Their restricted ranges and slow life history make them vulnerable to human impacts such as bycatch and habitat disturbance, leading to ongoing conservation concerns and protective measures in some regions.