Welcome to ...

The place where the world comes together in honesty and mirth.
Windmills Tilted, Scared Cows Butchered, Lies Skewered on the Lance of Reality ... or something to that effect.


Monday, May 11, 2015

Cave-Climbing Fish Found—Is It Evolution in Action?

Filmed shimmying up a cave wall in Ecuador, the catfish is likely a known species with a never before seen behavior, a new study says.
The catfish (seen climbing a 75-degree wall) likely uses water pressure and structures in their mouths and skin to stay attached.

This impressive climbing ability is due to "a number of modified structural elements of their fins, skin, and mouths," said Hoese, a naturalist and speleologist based in Austin, Texas.
"The thin film of water flowing over them as they climb likely provides pressure to help hold them to the wall, and these various structures help keep them from sliding down," he added. "They can then wriggle their way up, or also down, as you can see in the video."
Traveling Fish?
The puzzling thing about the new-found cave-climbing fish is that they don't appear to be adapted for underground life. These fish weren't colorless or blind, for instance, unlike other fish adapted to live in caves.
So what was C. microps doing down there in the darkness?
"This species is known to primarily eat algae, and as there's no sunlight in the caves, there's not much algae, so it seems unlikely that they are there to feed," Hoese said.
"The simplest explanation is that they simply occupy the fullest extent of the range they can reach," he added.
Picture of cave climbing fish 
Scientists suspect the cave-climbing fish is C. microps, a known species of suckermouth armored catfish.
Hoese noted the fish live in an Amazonian region where rivers are born in springs that issue from caves in the foothills of the Andes Mountains.
Maybe the catfish "just continue up the streams and into the springs, and on into the caves," he said.
Going to the Dark Side
Many fish have a natural instinct to head upstream, in order to breed, for example.
Another possibility is that the climbing catfish mark the beginnings of an evolving species of permanent cave-dwellers.
"Evolution is a process that's constantly at work," Hoese said. "It's interesting to look at examples where there may be changes, such as here, where we have a surface fish exhibiting specific behaviors and occupying an unusual habitat."
A model for comparison is another suckermouth catfish that the expedition team recorded, Astroblepus pholeter. A colorless species with miniscule eyes, it's already made the transition to cave life.
Right now there isn't the evidence to suggest C. microps is going to the dark side, but, said Hoese, "It's an exciting possibility."  

No comments: