What’s a hydra?

A hydra is a freshwater-dwelling cnidarian no more than a half-inch long that eats mostly insect larvae and crustaceans and is equipped with the ability to regenerate its body — even its head. Researchers at the University of California, Irvine, pinpointed the genetic machinery behind some of these tiny creatures’ powers of regeneration, which practically make them immortal. Their research was published in Genome Biology and Evolution on Dec. 8, 2021.