The only surviving member of the Neoceratodontidae family is the Australian lungfish, also known as the Queensland lungfish, Burnett salmon, and barramunda. It is the outgroup to all other members of the Devonian lineage and is one of six extant representatives of the ancient air-breathing Dipnoi (lungfishes) that lived during the Devonian period about 413–365 million years ago.

A man holding Australian lungfish
credit:abc.net.au

The five remaining freshwater lungfish species, four of which are found in Africa and one in South America, are physically significantly different from N. forsteri. Ceratodus, a small town in Queensland, takes its name from the Australian lungfish. The species was named after William Forster, a squatter and politician.

This group’s fossil records go back 380 million years, roughly when the higher vertebrate classes started to emerge. In northern New South Wales, fossils of lungfish that are nearly identical to this species have been discovered, showing that Neoceratodus has stayed practically unaltered for well over 100 million years, making it a living fossil and one of the world’s oldest vertebrate genera.

The existence of a single dorsal lung, utilized to augment the oxygen supply through the gills, is a distinguishing feature of the Australian lungfish. The lungfish can rise to the top and swallow air into its lung during periods of high activity, drought, or high temperatures, when water becomes deoxygenated, or when prevailing conditions prevent normal gill function.

When it employs the lung as a supplemental organ of respiration, more frequent air-breathing is linked to times of higher activity at night. Unlike other fish, the Australian Lungfish has the unique ability to breathe air with just one lung when streams grow stagnant or water quality deteriorates during dry periods.

Only the Mary and Burnett River basins in south-eastern Queensland are home to the Australian lungfish. In the last century, it has been successfully dispersed to other, more southerly rivers, including the Brisbane, Albert, Stanley, and Coomera Rivers, as well as the Enoggera Reservoir. The Australian lungfish has been introduced to the Pine, Caboolture, and Condamine Rivers, however, its current survival and reproduction success is unknown. At one time, there were at least seven different species of lungfish in Australia.

Body Structure

Australian lungfish navigating through it habitat
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Their bodies are elongated and stout, and their heads are flattened with small eyes. The mouth is tiny and situated subterminally. Lungfish can reach a maximum length of 150 cm and a weight of 43 kg. It’s usually around 100 cm long and weighs around 20 kg. The back, sides, tail, and fins of Australian lungfish are olive-green to dull brown, and the underside is a pale yellow to orange.

They have a reddish coloration on their sides that is significantly brighter in the males during the breeding season, according to reports. The lungfish’s only differentiating sexual trait is its coloration. Females grow to a somewhat bigger size than males, although both sexes have identical growth trends.

Habitat

This species prefers slow-moving rivers and quiet water with some aquatic vegetation growing along the banks. It grows on the bottoms of dirt, sand, or gravel. Lungfish live in small groups under submerged logs, dense banks of aquatic macrophytes, or underwater caves formed by soil being washed away under tree roots on river banks. They are commonly found in deep pools of 3–10 m depth and live in small groups under submerged logs, dense banks of aquatic macrophytes, or underwater caves formed by soil being washed away under tree roots on river banks.

The lungfish is cold-tolerant but prefers water temperatures between 15 and 25 degrees Celsius. The Australian lungfish cannot endure complete habitat desiccation, but it may survive for several days without water provided the surface of its skin is kept moist. Protopterus, unlike African species, does not withstand dry seasons by secreting a secretion.

A species of Australian lungfish in its territory
credit:labroots.com

Spawning

From August to December, the species spawns at night, with October being the busiest month. Fertilized eggs cling to aquatic plants for three weeks before hatching. Young grow slowly, reaching a length of 6 cm after 8 months and 12 cm after two years.

Feeding

Frogs, tadpoles, tiny fish, snails, shrimp, and earthworms are the most common food items. It will also consume plant matter. The Australian Lungfish’s eyesight is said to be weak, and the location of prey is supposed to be determined by scent rather than sight.

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