Fish
Australian Lungfish
Neoceratodus forsteri · also called australian lungfish, queensland lungfish, barramunda
The Australian lungfish is a big, heavy-scaled fish that has been swimming in Queensland’s rivers, essentially unchanged, since long before there were people, cattle, or grass on the plains around it. Fossils more than 100 million years old are nearly identical to the living animal. It breathes air through a single lung when the water turns bad — but, unlike its African and South American cousins, it cannot survive its pool drying up.
Overview
The Australian lungfish is native only to the Mary and Burnett rivers of southeast Queensland, with a few populations moved elsewhere by people. It grows to about 1.5 m and 40 kg, with a stout body, large overlapping scales, and paddle-shaped, almost limb-like paired fins. It eats frogs, small fish, snails, shrimp, and insect larvae, crushing them between horny tooth plates.
One lung
Where African and South American lungfishes have paired lungs, this species has a single lung running along its back. It breathes water through its gills most of the time and rises to gulp air only when its pool is warm, stagnant, or short of oxygen. Crucially, it cannot aestivate: it needs permanent water and dies if its river pool disappears, which makes it far more exposed to drought and water extraction than its relatives.
A living fossil
The genus Neoceratodus appears in the fossil record from over 100 million years ago in a form almost indistinguishable from the living fish. Lungfishes as a whole go back roughly 400 million years and sit close to the origin of land vertebrates. The Australian species is simply one of the least changed backboned animals on Earth.
A long, slow life
It matures at 15–20 years and can live for many decades. A captive lungfish named “Granddad,” held at an aquarium in Chicago, was estimated to be over 90 when he died in 2017.
Status
Listed as Endangered, the Australian lungfish is squeezed into a tiny natural range where dams, weirs, water extraction, and the loss of aquatic plant beds have cut the survival of young fish. Many populations now hold mostly ageing adults. The species is protected under Australian law.
Australian Lungfish: common questions
Why is the Australian lungfish called a living fossil?
Because the living animal looks almost exactly like its relatives did in the age of the dinosaurs. Fossils of the genus Neoceratodus from more than 100 million years ago show the same body shape, the same large scales, and the same distinctive crushing tooth plates as the fish swimming in Queensland rivers today. Lungfishes as a group are even older, going back some 400 million years, and they sit close to the point where the ancestors of land vertebrates split from other fish. The Australian species has simply changed very little over an enormous span of time, which is what the term living fossil is meant to capture.
Can the Australian lungfish breathe air like a land animal?
It can breathe air, but it cannot live out of water. It has a single lung along its back, and when its river pool becomes warm, still, or low in oxygen it rises to the surface and gulps air with a characteristic sound. This lets it stay active in conditions that would suffocate an ordinary fish. However, unlike the African and South American lungfishes, it cannot burrow into mud and survive a dry season, and it cannot move across land. Take it out of the water for long and it will die, so its air-breathing is a supplement to gill breathing, not a replacement.
How is it different from African and South American lungfish?
Several ways. The Australian lungfish has one lung; the others have two. It has large flipper-like paired fins; the others have thin, whip-like ones. It cannot aestivate, meaning it cannot survive its water drying up by cocooning in mud, whereas the African species famously can for months or even years. It also looks much more like the ancient fossil lungfishes than they do. Genetically the Australian lungfish branched off earliest, and the African and South American species are each other's closer relatives, a pattern that matches the break-up of the southern supercontinent.
Why is the Australian lungfish endangered?
Its natural range is tiny, just two river systems in southeast Queensland, and those rivers have been heavily modified. Dams and weirs block the fish from moving to spawning areas and change the flow and temperature of the water. Water extraction for towns and farms lowers river levels. And the fish will only breed successfully where there are dense beds of clean aquatic plants in flowing, oxygen-rich water, exactly the habitat that dams, sediment, and weed clearance tend to remove. As a result, many populations now contain mostly old adults with very few young fish coming through, and the species is protected under Australian law.