Resumen de Earth's first animals were made of jelly
Recent analyses of single genes had suggested that ctenophores could challenge sponges for the crown of most primitive animals. "People didn't believe it," says Ryan, admitting that he was among the skeptics. For more evidence, Ryan and his colleagues sequenced a full ctenophore genome, belonging to the species Mnemiopsis leidyi. Of the five groups of primitive animals that sit at the base of the animal tree--sponges, jellyfish, comb jellies, placazoa and bilaterians--ctenophores were the final group to have a genome sequenced.
