Head to head
Lungfish vs Coelacanth
Lungfish and coelacanths are the last of the lobe-finned fishes, the group from which every land vertebrate descends. They took opposite paths, one into shallow, seasonal fresh water, the other into the deep sea.
| Lungfish | Coelacanth | |
|---|---|---|
| Living species | Six | Two |
| Where it lives | Fresh water; Africa, S. America, Australia | Deep sea, 100 to 500 m; E. Africa and Indonesia |
| Breathing | True lungs; must breathe air (African, S. American) | Gills only |
| Reproduction | Lays eggs | Gives birth to live young |
| Drought survival | Seals in a mud cocoon for months to years | Not applicable; deep-sea |
| Rediscovery | Never lost | Found alive in 1938 after 66 million years |
| Closest to land animals | Yes, by most genetic evidence | Close, but slightly less so |
| Genome | Among the largest of any animal | Large, slowly evolving |
Lungfish vs Coelacanth: common questions
Are lungfish or coelacanths the ancestors of land animals?
Neither is a direct ancestor, but both are close relatives of the line that gave rise to tetrapods. Land vertebrates evolved from lobe-finned fishes in the Devonian, through now-extinct forms such as Tiktaalik, and the lungfish and the coelacanth are two surviving side branches of that broad group. For a long time the coelacanth was cast as the closest living link, but genetic and anatomical work over the past few decades has shifted the consensus toward the lungfish, which, unlike the coelacanth, have lungs, fleshy fins used for a bottom-walking gait, and other features that echo the fish-to-land transition. So a lungfish is currently the best living stand-in for the kind of animal from which legs and land life emerged.
How was the coelacanth rediscovered?
In December 1938, a museum curator in East London, South Africa, named Marjorie Courtenay-Latimer was called to look at the catch of a local trawler and spotted an extraordinary blue fish with limb-like fins among the pile. She could not preserve it in time and only a mounted skin and drawings survived, but the ichthyologist J. L. B. Smith identified it as a living coelacanth, a group known only from fossils up to 66 million years old, and named it Latimeria in her honour. A second population was found in the Comoro Islands in 1952, and a completely separate species was discovered in Indonesian markets in 1997. The find is often described as the zoological equivalent of meeting a living dinosaur.
Do lungfish and coelacanths ever occur together?
No. They live in entirely separate habitats. Lungfish are freshwater fish of swamps, floodplains, and slow rivers, mostly in warm, shallow, often seasonal water. Coelacanths are marine fish of cool, dark water on steep rocky slopes and in submarine caves, typically 150 to 250 metres down, and they cannot tolerate warm or shallow water, which is one reason they went unnoticed for so long. The two lineages last shared a common ancestor around 400 million years ago and have not overlapped since, so any resemblance between them reflects that deep shared ancestry rather than a shared way of life.