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The First Breath

Gogonasus

Gogonasus, the 380-million-year-old fossil sarcopterygian fish from Gogo in Western Australia, had large spiracles on its head to enable it to breathe air. Illustration: Brian Choo

By John Long

The African reedfish Polypterus has revealed how breathing first evolved in terrestrial animals, and perhaps how the structures of the ear first formed.

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A 100-year-old controversy in science has recently been solved by a team of fish physiologists at the Scripps Institute of Oceanography in San Diego after careful observation of various species of African reedfishes (Polypterus) in controlled laboratory conditions. As a result, we now know more about how our ancient fish ancestors first began to breathe air and, perhaps surprisingly, how we developed our capacity to hear.

Because Polypterus is one of the most primitive of all the living bony fishes (Osteichthyes), I was asked to help out by comparing what the researchers found with other ancient fishes. The results were published in Nature Communications on 23 January 2014.

But the story really begins with Napoleon’s crushing defeat by the British at Alexandria in 1801. While the two navies were squaring off, one of Napoleon’s appointed naturalists, Etienne Geoffrey Saint-Hillaire, was busy studying a new kind of strange and primitive-looking fish that dwelt in the Nile. When things turned sour for the French, he had to conclude his work rapidly and he brought his specimens of the fish back to France with him.

He named the fish Polypterus, meaning “many fins”. It had robust fleshy limbs like the coelacanths, which are related to the Queensland lungfish. Saint-Hillaire thought Polypterus to be living relicts related to an extinct line of fossil fishes...

The full text of this article can be purchased from Informit.