Jaw-Dropping Discovery in Jawless Fish

At a quick glance, jawless fish such as the lamprey above don't appear to have much in common with jawed fish or any other back-boned creature.

But, by looking beneath the skin, researchers have identified a jawless fish--the most ancient vertebrates at 500 million years old--that has evolved the means of generating extensive diversity in immune receptors, a trait previously believed to exist only in jawed vertebrates.

Immune receptors stud the surface of many types of immune cells and help control their behavior. While jawless fish immune receptors function in strikingly different ways than their jawed cousins', the receptors are similar and are governed by the same gene.

This research is detailed in the Dec. 23 issue of the journal Science.