The lungfish are a successful subclass of widespread lobe-finned fish from the Early Devonian-Holocene of the entire world. They, as a whole, were named in 1844 by Johannes Peter Müller. They are one of the most successful groups of animals to ever live (living for about 400 million years and still living today), and are famed for their ability to go onto land and form mucous cocoons in order to survive droughts.
Physiology[]
Lungfish are unique lobe-finned fish. They have a large, bulky body, a semi-small head with small jaws, and large, fleshy, lobe-like fins; however, instead of genuine teeth, they have large odontodes (dermal teeth) extending from their jaws, and their dorsal, anal, and caudal (tail) fins are all fused into one large caudal fin. Their bodies are covered in scaly skin.
Diet[]
Lungfish are omnivores, feeding on insects, crustaceans, worms, mollusks, amphibians, smaller fish, and plant matter. Even though they lack teeth, the odontodes extending their jaws are used for different purposes, depending on the order; some are designed for crushing hard food, while others are designed for cutting up small prey.
Lungfish genera (note that those are not all the ones that exist)[]
Dipterus[]
Dipterus is a dipterid dipteriform lungfish from the Late Devonian-Late Triassic of Belgium and the United States of America. It was named in 1828 by Adam Sedgwick & Roderick Murchison. Unlike modern lungfish, its dorsal, anal, and caudal fins were still separated; as well as this, its fins faced backwards and its caudal fin faced upwards, allowing it to gain small bursts of speed (as well as reducing any chance of its tail rubbing the bottom of its river habitat.
Ceratodus[]
Ceratodus is a ceratodontid ceratodontiform lungfish from the Late Triassic-Eocene of the entire world. It was named in 1837 by Louis Agassiz. It was one of the most successful lungfish genera to exist, surviving the deadly extinction events of the Triassic, Jurassic, and Cretaceous, and surviving up to the middle Paleogene; as well as this, the sharp true teeth on its jaws possibly indicate that it was more carnivorous than other lungfish genera.
Neoceratodus (Australian Lungfish)[]
The Australian lungfish (Neoceratodus forsteri) is a neoceratodontid ceratodontiform lungfish from the Oligocene-Holocene of Australia. It was named in 1870 by Johann Ludwig Gerard Krefft. It is the only surviving genus of ceratodontiform lungfish (all the other surviving genera are lepidosireniforms), and has gone unchanged for more than 28 million years (making it more of a living fossil than the West Indian Ocean/Indonesian coelacanth); as well as this, it is unable to secrete a mucous cocoon, and so, it is incapable of surviving droughts. This makes it different enough from the African lungfish (Protopterus species), which can secrete a mucous cocoon; this also makes it different enough from the South American lungfish (Lepidosiren paradoxa), which does not secrete a mucous cocoon, but does burrow into the mud and slow down its metabolism into a complete state of hibernation.