This strange and mesmerizing sea creature can age in reverse when times get tough, in a move that would make Benjamin Button ...

But starting in 2008, a series of studies rocked the base of the animal tree, suggesting that ctenophores (comb jellies) were the ancestral model instead. Yesterday (November 30), an international ...

Central to this debate is the question of which group represents the first branch of the animal family tree: sponges, the simple filter-feeders, or ctenophores, also known as comb jellies ...