Meet The World’s Oldest Fish—Presumed Extinct For 60 Million Years, Then Rediscovered In A Small Fishing Town

Prior to 1938, if you had asked a zoologist to name some of the oldest fish known to science, you’d probably hear about an oddly named lobe-fish, known as the coelacanth. The name itself sounds ancient. Coelacanths first evolved into existence during the early Devonian period, a little over 400 million years ago.

What this zoologist would not have told you is that this ancient fish could still be found in the ocean today. In fact, they probably would have chuckled at the idea. Scholars, prior to the coelacanth’s rediscovery in 1938, presumed that the coelacanth had gone extinct during the late Cretaceous period, 65-70 million years ago.

The coelacanth is an example of a “Lazarus taxon,” an animal that seemingly disappears from the fossil record only to be rediscovered in its same form millions of years later. This can happen for a number of reasons. More often than not, it highlights how sporadic and incomplete the fossil record is, especially when the number of individuals in a given taxon is low.

In the case of the coelacanth, the zoological community was upended in 1938 when a 32-year old museum employee, Marjorie Courtenay-Latimer, working in the small South African town of East London, was presented with a fish that could not be identified. It was caught by a local fisherman while fishing just outside of the mouth of the Chalumna River on the Eastern Cape of South Africa.

Courtenay-Latimer couldn’t identify the fish either, so she had it taxidermied and sought out the opinion of an expert–Professor James Leonard Brierley Smith, a university lecturer and an expert in marine life. When Brierley Smith received Latimer’s sketch and notes on the unidentified fish by mail, he responded via telegram with a now famous message: “MOST IMPORTANT PRESERVE SKELETON AND GILLS = FISH DESCRIBED.”

When Brierley Smith arrived in East London, he confirmed his hunch–the fish was indeed an ancient coelacanth. It was a discovery that sent shockwaves through the zoological community, earning both Brierley Smith and Courtenay-Latimer international recognition.

Interestingly, a second specimen wasn’t discovered for another 15 years. The second coelacanth was found in 1952 by two fishermen of the Comoro Islands–a small island chain nestled in between Madagascar and mainland Africa.

In the 1990s, scientists made another noteworthy discovery, finding a second species of coelacanth in the Indonesian islands. Thus, as it stands today, coelacanths fall into one of two species: the West Indian Ocean coelacanth (Latimeria chalumnae), primarily found near the Comoro Islands off the east coast of Africa, and the Indonesian coelacanth (Latimeria menadoensis).

Here are a few of the reasons why the ancient coelacanth has been able to stand the test of time.

• Adaptations. Coelacanths have a number of unique physiological traits that have suited them well over millions of years. For instance, their lobed pectoral fins, which are thought to be precursors to the limbs of terrestrial vertebrates, are well-adapted for maneuvering in deep, complex underwater environments.
• Stable environment. Coelacanths inhabit deep, stable environments, like underwater caves and the deep sea, which have not changed much over geological time. These environments have fewer predators and less competition, helping the coelacanth avoid drastic evolutionary pressures.
• Low metabolism. Coelacanths have a relatively low metabolic rate, which allows them to survive in environments where food may be scarce. Their slow metabolism contributes to their ability to withstand long periods of environmental change.
• Specialized niche. Their ecological niche—typically in deep, cold waters—hasn’t changed much. This stability in their habitat means they’ve faced less pressure to adapt compared to species living in more variable environments.

Overall, the coelacanth’s combination of evolutionary adaptations, environmental stability, and specialized ecological niche has helped it persist through significant changes in Earth’s history.