Thursday, 18 October 2007

Fish out of water

The world contains many wonders that creationists ought to have a hard time explaining. Forest-dwelling penguins, almost-flightless bats, and my all-time favourite, the tree kangaroo. I mean, what sort of twisted deity would create a kangaroo that lives up a tree? The poor things keep falling out and breaking their legs. Not too surprising, then, that scientists have also found the ultimate evolutionary oxymoron: the ground-dwelling tree kangaroo.

A new gold-medal contender for biological weirdness, however, now enters the lists: the tree fish.

Scientists discovered this unlikely creature, a species of mangrove killifish, hiding in rotting branches in swamps in Florida and Belize. They (the fish, that is, not the scientists) had slithered up from drying pools of water around mangrove roots, and into cavities made out by insects, where they were found lined up "like peas in a pod". To cope with their un-fishlike habitat, they had developed specialised gills and excreted through their skin.

Odd things, these killifish. They're also the only known vertebrate capable of fertilising itself. They develop both male and female organs, and their eggs are (almost uniquely for fish) fertilised inside their bodies before being deposited in the water.

"They really don't meet standard behavioural criteria for fish.", said Dr Scott Taylor, of Florida, announcing the discovery. Nuff said.

Full story: from The Telegraph.