What is a coelacanth?

The coelacanth is a rare fish belonging to the genus Latimeria . Once thought to be extinct for millions of years, a living specimen was discovered in 1938. They are characterized by their hollow fin spines. Coelacanths are large, averaging about 5 feet (1.5 meters) in length and weighing around 100 pounds (45 kg), and are known as powerful predators. These fish are slow-growing and can live up to 100 years, reaching sexual maturity between 40 and 69 years of age. They are live-bearers, with females carrying their young for about five years before giving birth. Coelacanths inhabit mesopelagic waters at depths of 650–1,300 feet (200–400 meters). The African coelacanth is considered a critically endangered species, while the Sulawesi coelacanth is classified as vulnerable.

Why are coelacanths considered special among fish?

Coelacanths are considered special among fish for several reasons:

Where were coelacanths first discovered?

The first living coelacanth was discovered in 1938. It was netted in the Indian Ocean near the southern coast of Africa. For years, scientists believed that coelacanths had gone extinct about 66 million years ago. In 1952, a second coelacanth was found near the Comoros Islands. The islanders were familiar with the fish, and they would eat the flesh dried and salted. They also used the scales as an abrasive. In 1998, a second species of coelacanth was discovered in Indonesia and is known as the Sulawesi coelacanth.

What do coelacanths look like and how do they move?

Coelacanths are lobe-finned bony fish with two known living species: the African coelacanth and the Sulawesi coelacanth. They have heavy, mucilaginous bodies and highly mobile, limblike fins, averaging about 5 feet (1.5 meters) in length and 100 pounds (45 kg) in weight. Coelacanths move using their paired pectoral and pelvic fins, which have fleshy stalks supported by segments of bone or cartilage. They also have a powerful three-lobed tail fin, with the posterior end of the notochord extending into the middle lobe. The primary form of locomotion among fish is swimming via lateral undulations of the body.

Why were coelacanths thought to be extinct?

Coelacanths were presumed extinct because the youngest known fossils dated back to the end of the Cretaceous Period, 145 million to 66 million years ago. However, this belief was overturned in 1938 when a living coelacanth, Latimeria chalumnae , was discovered in the Indian Ocean near South Africa. The unexpected rediscovery of this ancient fish, thought to have vanished with the dinosaurs, captured global attention. Later, in 1998, a second species, Latimeria menadoensis , was found in Indonesia. Both species are now considered threatened.

How do scientists study and protect coelacanths today?

Modern coelacanths, belonging to the family Latimeriidae, are of the genus Latimeria . Once believed to be extinct, two living species exist today: the African coelacanth ( Latimeria chalumnae ) and the Sulawesi coelacanth ( L. menadoensis ). Because both species are considered threatened, scientists study them to inform conservation efforts. Field research projects and an extensive array of technologies are deployed in gathering and analyzing data. Acoustic telemetry and satellite tags track the coelacanths' movements and transmit data such as depth, location, and heart rate. DNA bar coding is also used in cataloging collected specimens. Studies of growth rings in the scales of African coelacanths help determine their age and when they become sexually mature.

coelacanth

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Illustration of an African coelacanth (Latimeria chalumnae), a rare deep-sea fish with a thick, blue-scaled body, lobed fins, and a distinctive rounded tail.

Why do coelacanths' fins look like legs?

Illustration comparing two crossopterygian fishes: the long, slender, brown-and-green Devonian rhipidistian Eusthenopteron foordi above, and the robust, blue African coelacanth Latimeria chalumnae below.

Explore the dark undersea depths of Indonesian waters in search of prehistoric sea life and discover two coelacanths

Quick Facts

Related Topics:: deep-sea fish; African coelacanth; Sulawesi coelacanth

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coelacanth

fish

Also known as: Latimeria

Written and fact-checked by

Britannica Editors

Last updated

Oct. 1, 2026 •History

Top Questions

What is a coelacanth?
The coelacanth is a rare fish belonging to the genus Latimeria. Once thought to be extinct for millions of years, a living specimen was discovered in 1938. They are characterized by their hollow fin spines. Coelacanths are large, averaging about 5 feet (1.5 meters) in length and weighing around 100 pounds (45 kg), and are known as powerful predators.

These fish are slow-growing and can live up to 100 years, reaching sexual maturity between 40 and 69 years of age. They are live-bearers, with females carrying their young for about five years before giving birth. Coelacanths inhabit mesopelagic waters at depths of 650–1,300 feet (200–400 meters). The African coelacanth is considered a critically endangered species, while the Sulawesi coelacanth is classified as vulnerable.
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Why are coelacanths considered special among fish?
Coelacanths are considered special among fish for several reasons:
- Ancient lineage Coelacanths appeared roughly 400 million years ago during the Devonian Period.
- "Living fossils" They were thought to have been extinct for millions of years until a living specimen ( Latimeria chalumnae) was discovered in 1938.
- Evolutionary significance Coelacanths belong to a group of fish known as Sarcopterygii. Some believe that they are related to the ancestors of land vertebrates.
- Unique anatomy They have distinct features, such as fleshy, lobed fins, an intracranial joint, and a rostral organ with electroreceptive cells.
- Slow-growing and long-lived Coelacanths can live up to 100 years and reach sexual maturity between 40 and 69 years of age.
- Rarity There are only two known living species: the African coelacanth (Latimeria chalumnae) and the Sulawesi coelacanth (L. menadoensis), both of which are considered threatened.
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Where were coelacanths first discovered?
The first living coelacanth was discovered in 1938. It was netted in the Indian Ocean near the southern coast of Africa. For years, scientists believed that coelacanths had gone extinct about 66 million years ago. In 1952, a second coelacanth was found near the Comoros Islands. The islanders were familiar with the fish, and they would eat the flesh dried and salted. They also used the scales as an abrasive. In 1998, a second species of coelacanth was discovered in Indonesia and is known as the Sulawesi coelacanth.
1 Britannica Source
1. coelacanth
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What do coelacanths look like and how do they move?
Coelacanths are lobe-finned bony fish with two known living species: the African coelacanth and the Sulawesi coelacanth. They have heavy, mucilaginous bodies and highly mobile, limblike fins, averaging about 5 feet (1.5 meters) in length and 100 pounds (45 kg) in weight.

Coelacanths move using their paired pectoral and pelvic fins, which have fleshy stalks supported by segments of bone or cartilage. They also have a powerful three-lobed tail fin, with the posterior end of the notochord extending into the middle lobe. The primary form of locomotion among fish is swimming via lateral undulations of the body.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why were coelacanths thought to be extinct?
Coelacanths were presumed extinct because the youngest known fossils dated back to the end of the Cretaceous Period, 145 million to 66 million years ago. However, this belief was overturned in 1938 when a living coelacanth, Latimeria chalumnae, was discovered in the Indian Ocean near South Africa. The unexpected rediscovery of this ancient fish, thought to have vanished with the dinosaurs, captured global attention. Later, in 1998, a second species, Latimeria menadoensis, was found in Indonesia. Both species are now considered threatened.
1 Britannica Source
1. coelacanth
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do scientists study and protect coelacanths today?
Modern coelacanths, belonging to the family Latimeriidae, are of the genus Latimeria. Once believed to be extinct, two living species exist today: the African coelacanth (Latimeria chalumnae) and the Sulawesi coelacanth (L. menadoensis).

Because both species are considered threatened, scientists study them to inform conservation efforts. Field research projects and an extensive array of technologies are deployed in gathering and analyzing data. Acoustic telemetry and satellite tags track the coelacanths' movements and transmit data such as depth, location, and heart rate. DNA bar coding is also used in cataloging collected specimens. Studies of growth rings in the scales of African coelacanths help determine their age and when they become sexually mature.
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Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

coelacanth, (genus Latimeria), any of the two living lobe-finned bony fishes of the genus Latimeria. Traditionally, however, coelacanth was the name applied generally to any member of the order Coelacanthiformes, subclass Crossopterygii. Members of the related but extinct suborder Rhipidistia are considered to have been the ancestors of land vertebrates. In some systems of classification, the coelacanths and rhipidistians are considered separate orders, members of the subclass Crossopterygii. There are two living species: the African coelacanth (Latimeria chalumnae), found in the Indian Ocean near the coasts of southeastern Africa, Madagascar, and the Comoros; and the Sulawesi coelacanth (L. menadoensis), which inhabits the waters near northern Sulawesi in Indonesia.

Modern coelacanths belong to the family Latimeriidae. The name refers to their hollow fin spines (Greek: koilos, “hollow,” and akantha, “spine”). The modern coelacanths are bigger than most fossil coelacanths and are powerful predators with heavy mucilaginous bodies and highly mobile limblike fins. They average 5 feet (1.5 metres) in length and weigh about 100 pounds (45 kg). Coelacanths are slow-growing and long-lived; studies of growth rings in the scales of African coelacanths suggest that these fishes become sexually mature when they are between 40 and 69 years old and may live as long as 100 years. They are live-bearers that give birth to well-developed young. One study reports that female African coelacanths carry their young about five years before giving birth. Though once thought to be deepwater fishes, coelacanths are now known to inhabit mesopelagic waters, below the continental shelf, at depths of some 650–1,300 feet (200–400 metres).

Coelacanths appeared about 400 million years ago during the Devonian Period and were abundant over much of the world. The largest known forms included members of the genera Mawsonia and Rebellartrix that lived during the Cretaceous and early Triassic periods, respectively, and grew to between 4 and 6 metres (13.1 and 19.6 feet) long.Coelacanthus, the genus from which the order Coelacanthiformes was derived, has been found as fossils in rocks from about 259 million to about 252 million years ago, from the late Permian Period to the beginning of the Triassic Period. Coelacanthus, like other coelacanths, showed a reduction in bone ossification and a general trend toward a marine mode of life away from the earlier freshwater environment. The youngest known fossil coelacanths date to the end of the Cretaceous Period, 145 million to 66 million years ago.

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It was long supposed that coelacanths became extinct about 66 million years ago, but in 1938 a living member (Latimeria chalumnae) was netted in the Indian Ocean near the southern coast of Africa. Rewards were offered for more specimens, and in 1952 a second (named Malania anjouanae but not separable from Latimeria) was obtained near the Comoros Islands. Numerous others have been caught in that area. It was later discovered that these fishes were well known to the islanders, who considered the flesh edible when dried and salted; the rough scales were used as an abrasive. A second species of Latimeria was discovered in Indonesia in 1998. Known commonly as the Sulawesi coelacanth, its scientific name, L. menadoensis, derives from the island of Manado Tua, from which it was collected. Both species are considered threatened by the International Union for the Conservation of Nature and Natural Resources, the African coelacanth being classified as a critically endangered species and the Sulawesi coelacanth being classified as a vulnerable species.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Adam Augustyn.

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