True blue living fossils

19 August, 2010

Two Australian Lungfish
Two of the Australian Lungfish on display in 600 Million Years: Victoria Evolves at Melbourne Museum.
Image: Benjamin Healley
Source: Museum Victoria

The museum’s preparators create models of prehistoric animals that are so vivid and lifelike that you almost expect the displays to move. But in 600 Million Years: Victoria Evolves, the prehistoric fish do move, because they’re alive!

The Australian Lungfish, Neoceratodus forsteri, is often called a ‘living fossil’ since its basic body form has changed very little in 150 million years. Alongside models of early tetrapods like Acanthostega, three live lungfish are part of the museum’s display about the evolution of land vertebrates. “We’ve had some wonderful moments because visitors think they’re all models,” said Alan Henderson of Live Exhibits. “They sit still for quite a while, with the models next door, but then one of the lungfish moves!” Every few minutes, the fish rise to the water surface to gulp air into their single lungs.

The lungfish came from Macquarie University researcher Professor Jean Joss, who bred them in captivity 16 years ago. They belong to a group called the lobe-finned fish (or Sarcopterygii) that first arose in the Silurian Period around 418 million years ago. Their fleshy, strong fins were the precursor to the basic limb structure shared by all vertebrates, including ourselves. Only a handful of lobe-finned fish survive today; most living bony fish belong to the Actinopterygii or ray-finned fish, such as tuna, salmon and carp.

Professor Joss studies the biology of lungfish because they are the closest living relative to our ancient ancestors. By learning more about lungfish we learn more about all tetrapods (the four-limbed animals with a backbone, namely birds, mammals, reptiles and amphibians). The Australian Lungfish is a protected species and is found only in a few rivers in south-eastern Queensland, so the museum is grateful to Professor Joss for providing three of these rare and amazing creatures. Wild Australian Lungfish populations are falling due to drought, habitat destruction by human activity and invasive fish species.

Since arriving in June, the fish have settled in well and are surprisingly active; as Jessie Sinclair from Live Exhibits explained. “They do enjoy their food. We’re finding they’ve got a decent appetite and spend a lot of time grazing like vacuum cleaners. They seem to polish off anything they can get their mouth around.” The Live Exhibits keepers monitor what each fish eats and hand-feed them earthworms and fish pellets. A bacterial filtration system and regular monitoring ensures the water remains balanced and conditioned for good health.

Their tank is a roomy 2.5m long to give them lots of room to grow. “They’re only in their teens and they have a long way to go,” explained Jessie. “They do a lot better when they live in groups which is why we have three fish.” Australian Lungfish can live for decades and reach over a metre in length. This large tank will suit them for many years before they will require a bigger enclosure.

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