Tag: Regeneration

Hydras might look like they’re visitors from outer space, but they’re actually Earth-dwelling animals that can be found in fresh water, like ponds or gentle streams. The body of a hydra consists of a thin tubelike stalk that’s about an inch long with several tentacles extending from one end. Some hydras can grow an armlike extension that eventually pops off the main stem to become a new hydra.

Humans have studied hydras for hundreds of years. Antonie van Leeuwenhoek, one of the earliest known microscopists, first described them in 1703 when he looked at water samples under a microscope. You can see hydras—whose bodies are about the length of a paperclip—without them, but microscopes help researchers see their shape in better detail. Scientists commonly use hydras as research organisms because of their incredible ability to regrow lost body parts after injury through a process called regeneration.

The friendly-looking axolotl (Ambystoma mexicanum) doesn’t seem to have much in common with its namesake, Xolotl—the Aztec god of lightning, death, and fire. In fact, axolotls can regrow lost limbs and other body parts like organs and parts of their central nervous systems—which goes against the concept of death!