Coelacanth - An Example of a Lazarus Taxon

Coelacanths are a group of ancient fish that first appeared more than 360 million years ago. It was believed to have gone extinct from the fossil records about 66 million years ago, but only for it to be rediscovered in 1938 off the coast of South Africa. Furthermore, coelacanths are of special interest to palaeontologists because they consider this species a “living fossil”. This means that the species has essentially remained unchanged from earlier geological times. Interestingly, coelacanths are more closely related to tetrapods and lungfish than other ray-finned fish.

Species

Currently, there are two extant species of coelacanths: the West Indian Ocean Coelacanth (Latimeria chalumnae) and the Indonesian Coelacanth (Latimeria menadoensis). The latter (Latimeria chalumnae) is considered by the IUCN to be critically endangered, with an estimated population size of 500 or fewer individuals. On the other hand, IUCN considers Latimeria menadoensis to be Vulnerable, with a population size of 10,000 individuals or less.

Description

Coelacanths are relatively large fish, often growing more than 6.6 ft in length and weighing around 90 kilos. This species also has a long lifespan, with individuals reaching 60 years of age or more. Coelacanths are carnivorous and hunt at night. Their diet primarily consists of fish and cephalopods such as squids. Interestingly, these fish are known as “passive drift feeders”, which means they drift along with the currents and feed on whatever prey they encounter. They also show sexual dimorphism, with females growing larger in size than males. Coelacanths are also ovoviviparous animals, which means the females hold the fertilized eggs within their body while the embryos develop.

Also Read:

• What is a Lazarus Taxon?
• What Is Extinction? – Causes And Examples

Explore more fascinating topics on Coelacanth or discover other interesting topics by registering at BYJU’S Biology.