Tag : Gills

Washington: Well before evolving to help vertebrates breathe underwater, gills played an early and equally important role in regulating the salt and pH balance of blood, according to surprising new research. But surprising new research published in Nature is adding a new, early chapter to the evolutionary story of gills. "Our work suggests that the early, simplified gills of our worm-like ancestors played an important role in ion regulation. And that role might have originated as early as the very inception of gills, well before they played any role in breathing," says Dr. Michael Sackville, a zoologist who led the study while with the University of British Columbia (UBC). "This really does flip the script on our understanding of how gills and gill function evolved." The evolution of gills and lungs has fascinated biologists, including Darwin, for more than 100 years. Prior to this study, gills were thought to be first used for breathing and ion regulation near the very beginning of vertebrate life. In this traditional timeline, these two functions shifted from the skin to the gills in tandem, helping vertebrates transition from small, worm-like creatures to larger, active fishes. This transition from "small and wormy" to "big and fishy" is an iconic event in vertebrate evolution. The study traced the evolutionary journey of gills by comparing three animals that are alive today, but belong to different lineages: lampreys, which are vertebrates, and amphioxus and acorn worms, which are close relatives of vertebrates. The researchers assumed that any gill functions shared between the animals were inherited from a common ancestor, which is believed to be when simple gills first appeared well over 500 million years ago. "We found tha ...