Coelacanth facts, pictures and in-depth information.
Coelacanths are sometimes known as ‘living fossils’; animals that have changed little over millions of years. These ancient fish are more closely related to four-limbed vertebrates (including humans) than they are to many fishes.
For many years coelacanths were only known from fossils – it was thought that they had become extinct around 70 million years ago.
Incredibly, a living coelacanth was caught off the coast of South Africa in 1938 – in effect, bringing the coelacanths ‘back from the dead’. Since then, numerous other coelacanths have been caught and today two living species are recognized. One of these – the West Indian coelacanth – is rated ‘Critically Endangered’; it is thought that fewer than 500 survive.
Read on to find out more about these fascinating fish …
Coelacanth Facts At A Glance
- Other name(s): Latimeria
- Animal Order: Coelacanthiformes
- Type of Animal: Fish
- Where Found: Northern Sulawesi and the eastern coast of Africa
- Length: Up to 2 m (6 ft. 6 in)
- Weight: Up to 90 kg (200 lb.)
- Conservation Status
- West Indian coelacanth: Critically Endangered
- Indonesian coelacanth: Vulnerable
Meet The Coelacanths: Introduction
Coelacanths belong to an order of fish – Coelacanthiformes – that was once only known from fossilized remains. It was believed that the last coelacanths become extinct around 66-70 million years ago, during the late Cretaceous period.
In 1938 the scientific world was rocked by the discovery of a living coelacanth. Today, two extant (living) coelacanth species are known: the West Indian coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis).
Approximately 80 coelacanth species are known from fossils.
Coelacanths are more closely related to tetrapods (four-limbed vertebrates) than to ray-finned fish (which make up the majority of other living fish species). It has been suggested that coelacanths form a direct evolutionary link between the groups. However, this theory is not supported by current evidence.
The coelacanths’ closest living relations are the air-breathing lungfishes, found in Africa, South America and Australia.
The name Coelacanthiformes is derived from Greek and means ‘hollow spine’.
What Do Coelacanths Look Like?
The two extant coelacanth species are very similar in appearance. Each has a large, stocky body that is protected with thick scales. Individual coelacanths have a unique pattern of white speckling.
The coelacanths have eight fleshy, lobed fins: a pair of dorsal fins, a pair of pectoral fins, a pair of pelvic fins and a single anal fin and caudal fin. The caudal (tail) fin is divided into 3 sections, with a secondary tail extending past the main one.
Female coelacanths are usually larger in size than the males, and modern coelacanths appear to be larger than their extinct relatives.
Unusual Anatomical Features
The coelacanths have several curious internal characteristics that are either unique to the order or rare in other vertebrates.
At the back of the coelacanth skull there is a hinged joint that allows the animal to open its jaws extremely wide. Instead of a backbone, a coelacanth has a fluid-filled, hollow notochord.
The heart of the coelacanth is shaped like a straight tube, and its braincase is filled mostly with fat (brain tissue takes up only 1.5% of the space). Instead of a swim bladder, the coelacanth has a fatty organ, and its 2 kidneys are fused together.
Where Are Coelacanths Found?
Coelacanths are found along the east coast of Africa and near Sulawesi, Indonesia.
The largest known population of the West Indian coelacanth is found near the Comoro Islands, which lie between the African mainland to the east of Mozambique, and Madagascar. Smaller breeding populations or individuals have also been found in the waters of Kenya, Tanzania, Mozambique, South Africa and Madagascar.
The Indonesian coelacanth has been observed off the coast Manadotua, an island near the northern tip of Sulawesi.
Coelacanths inhabit temperate waters (i.e. waters that are neither tropical nor polar). During the day, they are usually found in shallow underwater caves and crevices in volcanic slopes at depths between 150 and 240 m (500 and 800 ft.). At night they may swim to deeper waters.
Coelacanths are known to cluster together inside caves during the day, although no social interactions have been observed between individuals and the animals appear to avoid physical contact. During the night, coelacanths come out and hunt alone.
Coelacanths have a rostral organ in their snout, which can detect electric currents. It is unclear what the organ is used for, but it may play a role in avoiding obstacles, recognizing individuals or locating prey.
Coelacanths have a unique swimming style: their limb-like fins move in a synchronized, alternating pattern that resembles a horse galloping. Coelacanths are exceptionally agile and able to swim in any direction.
Coelacanth Life Cycle
Very little is known about coelacanth mating behavior, but each brood appears to be fathered by a single male. It’s thought that the male may use a modified organ to fertilize the female internally.
Coelacanths are ovoviviparous: the fertilized eggs remain inside the female’s body and the young are born fully formed. Gestation is thought to take between 13 months and 3 years, during which time the embryos get nourishment from the egg’s yolk sac.
Only 2 female coelacanths carrying young have been recorded: one had 5 pups and the other had 26 pups. The young (that were near full term) measured about 35 cm (14 in) and weighed roughly 500 g (18 oz.). Otherwise very similar to the adults in appearance, the young have eyes that are larger relative to body size, and the downward slope of their body is more prominent.
What Do Coelacanths Eat?
Coelacanths eat other fish as well as cephalopods such as cuttlefish and squid.
Although capable of fast movements, the feeding style of coelacanths is passive and opportunistic. Rather than pursuing prey, the animals tend to drift slowly, waiting for a suitably-sized morsel to appear close enough to their mouths for them to grab.
Humans are the only known predators of coelacanths, although the observed panic behavior when the coelacanths are approached by foreign bodies, together with the bite marks seen on some individuals, suggest that coelacanths are preyed upon by some large deep-water predators.
The color pattern of the coelacanths’ scales resembles the appearance of their cave habitats. This suggests that coelacanths avoid predators by blending into their environment.
Are Coelacanths Endangered?
The West Indian coelacanth is rated ‘Critically Endangered’ by the IUCN, while the Indonesian coelacanth is rated ‘Vulnerable’.
There may be fewer than 500 West Indian coelacanth individuals left in the world. The Indonesian coelacanth population size is estimated to be fewer than 10,000 individuals.
Coelacanths are considered worthless as human food (their flesh is slimy and difficult to digest). Although they are not targeted by fishermen they are often caught accidentally in gill nets and during deep-sea trawling.