An ancient lobe-finned fish
Coelacanths belong to the lobe-finned group Sarcopterygii. Their closest living relatives are lungfish, although relationships among ancient lobe-finned fish remain an active area of study.
4u2Stay · Nature’s Explorers · Deep marine science
The Coelacanth: A Living Window into Deep Time
A coelacanth is not a fish frozen unchanged in the past. It is a living, highly specialised lobe-finned fish whose lineage reaches back hundreds of millions of years.
In 1938, a strange blue fish brought ashore in South Africa changed the history of natural science. Today, the African or West Indian Ocean coelacanth, Latimeria chalumnae, is one of the extraordinary animals associated with the deep waters of the western Indian Ocean and the iSimangaliso Marine Protected Area.
Explore the coelacanth chapters
What is a coelacanth?
Remarkable anatomy
Features include fleshy paired fins supported by internal bones, a special electrosensory rostral organ, a hinged skull, a persistent fluid-filled notochord, an oil-filled buoyancy organ and a distinctive three-lobed tail.
Use “living fossil” carefully
The phrase is a useful public nickname, but living coelacanths are modern animals that have continued evolving. They are not unchanged fossils and they are not direct human ancestors.
From fossils to a living fish
Deep-time lineage
The earliest known coelacanth fossils date to approximately 420 million years ago in the Devonian period. Fossil coelacanths were more diverse than the two living species known today.
The 1938 South African discovery
On 22 December 1938, Marjorie Courtenay-Latimer noticed an extraordinary fish among a trawl catch brought ashore in South Africa. J.L.B. Smith recognised its relationship to coelacanth fossils and described Latimeria chalumnae.
Two living species
Latimeria chalumnae is the African or West Indian Ocean coelacanth. Latimeria menadoensis is the Indonesian coelacanth. They are related but genetically distinct.
Coelacanths and iSimangaliso
The iSimangaliso story extends from lakes, estuaries, wetlands and beaches into deep offshore ecosystems.
Jesser Canyon and Sodwana
On 28 October 2000, mixed-gas divers Pieter Venter, Peter Timm and Etienne le Roux discovered living coelacanths at approximately 104 metres in Jesser Canyon off Sodwana Bay. The site is within the iSimangaliso Marine Protected Area.
Not St Lucia Estuary
Coelacanths should not be described as living in the St Lucia Estuary. The relevant South African records concern deep offshore marine habitats, particularly submarine canyons around Sodwana and the iSimangaliso marine area.
ACEP research
The African Coelacanth Ecosystem Programme supports multidisciplinary work using mixed-gas diving, submersibles, remotely operated vehicles, research vessels, mapping, telemetry, imagery and environmental DNA.
Life in the deep
Rocky habitat
Coelacanths are associated with steep rocky slopes, overhangs and submarine caves. These environments are difficult and expensive to study, so major questions remain about behaviour and population sizes.
Feeding and movement
They are generally slow-moving near the seabed and are described as passive drift feeders, but can move quickly to capture prey or avoid danger. Their diet includes fish and cephalopods such as squid, cuttlefish and octopus.
Environmental DNA
eDNA can detect genetic material released into water without requiring every animal to be seen. It indicates DNA in sampled water; it does not by itself count the population or reveal an exact total.
Reproduction and conservation
Unusual reproduction
Scientific and museum sources describe internal fertilisation, eggs developing inside the female and live birth of fully formed young. Important questions remain about mating, gestation, birth sites and newborn survival.
Conservation challenges
Deep habitat, accidental capture, fishing pressure, disturbance and limited monitoring make protection difficult. Conservation must support non-invasive research and protect confidential locations.
No guaranteed sighting
A coelacanth is not a guaranteed sighting for visitors to St Lucia, Sodwana or iSimangaliso. Responsible tourism puts the animal and habitat ahead of access or photography.
Nature’s Explorers family learning
The coelacanth story connects deep time, fossils, living animals, scientific evidence, local marine knowledge and conservation.
Questions to explore
How do scientists know what lived millions of years ago? What changes when a fossil species is found alive? How can DNA in water help researchers without disturbing animals?
Evidence, not fantasy
The aim is not to turn the coelacanth into a fantasy creature or promise a sighting. It is to show how fossils, museums, divers, universities, local knowledge and modern research build understanding.
Scientific references
Explore the science responsibly
Ask 4u2Stay about the Sodwana and iSimangaliso marine story, Nature’s Explorers learning and family-friendly destination planning.