Light shed on fish gill mystery

[n2doc]

By Victoria Gill (Now That's an appropriate name!)
Science reporter, BBC News

Biologists have cast doubt on the long-held theory that fish gills evolved primarily for the purpose of breathing.
The researchers studied the development of gills in rainbow trout larvae.
Their experiment suggests that it is likely that fish evolved gills for the primary purpose of regulating the chemicals in their bodies.
The team reports in the Royal Society journal Proceedings B that this developmental study gives an insight into the evolution of fish gills.
Clarice Fu, a zoologist from the University of British Columbia in Canada, led the study.
She and her colleagues found, as the larvae matured, their gills developed the ability to regulate the chemicals in their blood earlier than they began to take up oxygen.
To discover this, the team measured the uptake of ions, which are charged chemical particles, such as sodium.

more

http://news.bbc.co.uk/2/hi/science/nature/8454592.stm