Creek Running North

Everyone other than Lauren should look below the fold.

Cute little thing, isn’t it? It’s a Neoceratodus forsteri, the Queensland lungfish. Neoceratodus is one of six species of lungfish still living, all of them hailing from old Gondwanaland: Australia, Africa, and South America. Of all living fish, lungfish are the ones most closely related to Lauren, and to me, and to every other mammal and reptile and bird and amphibian on the planet.

Neoceratodus is, in a sense, one of the transitional forms the creationists yammer on about us not having. It’s called a lungfish because it can breathe air, an adaptation that arose in the Devonian and — as I understand current thinking — allowed our mutual ancestors to thrive in shallow, stagnant and thus unoxygenated swamps by sticking their heads out of the water and into the atmosphere, an act roughly equivalent to our learning how to breathe on the moon.  A number of other animal lineages made the jump as well, the insects and chelicerates, crustaceans and molluscs and I’m certainly neglecting others. But what we biased tetrapods tend to think of as terrestrial animals — elephants and dinosaurs and Lauren and frogs and bats and Zeke and Dick Cheney and goats — we’re all here because an ancestral population of lungfish poked their heads out of the water, liked what they saw, and pushed themselves up onto land on stumpy ventral limbs that eventually evolved into hands and feet and wings and talons and flippers.

I’ve never really liked the phrase “living fossil.” You and the Queensland lungfish are equally distant, after all, from those Devonian colonizers. But Neoceratodus has, as a genus, remained more or less unchanged through perhaps 100 million years of evolution, more than a quarter of the length of time since the Devonian. They’ve evolved away from the first lungfish just like we have, but studying them provides a pretty good glimpse into what those ancient fish might have been like, from bones to behavior to genome.

And PZ informs us that the Queensland lungfish is threatened. Its range in the Mary and Burnett river systems in northeastern Australia has been targeted for development as reservoirs to slake the thirst of new Oz suburbs. Neoceratodus breeds in shallow foliage-filled areas not entirely unlike the swamps from which the Devonian lungfish hauled themselves, but reservoirs’ water levels fluctuate too much to maintain such shallows. Neoceratodus breed slowly, and cutting off their breeding habitat may doom them. A dam on the Burnett River is underway, and a dam on the Mary was approved last week.

PZ’s got email addresses of relevant Australian officials who need your (polite) letters in defense of the lungfish here, along with much more information on this fascinating critter. He’s asked for your help: Go take a look.

[Geographical error corrected: see comments. — C]