Understanding the Immortal Hydra

by Greg Watry

Hydra under microscope

Hydra, which measure just millimeters in length, are studied by biologists for their regenerative capabilities and uncharacteristic longevity. Stefan Siebert/Juliano Lab

The hydra is a small freshwater invertebrate named after the fearsome monster of Greek mythology that grew two new heads for each one cut off. Now the real hydra’s ability to regrow pieces of itself is attracting growing interest from regenerative biologists as this tiny, jellyfish-like creature may hold within its genomic code the key to biological immortality.