Details
Hydra vulgaris
Hydra is a tiny freshwater cnidarian that anchors to plants or stones. It waits with tentacles spread to catch minute animals.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It lives in ponds, lakes, and slow freshwater across the Palearctic and Nearctic. Plants, stones, leaves, and artificial surfaces provide attachment sites.
Length 0.5-3 cm; weight 0.01-0.1 g. A tubular body bears a ring of fine tentacles around the mouth, with a basal disc at the opposite end. It stretches and contracts dramatically.
Cathemeral and solitary, it usually waits while attached. It can also move by looping or somersaulting across a surface.
A carnivore, it stings water fleas, tiny crustaceans, and larvae with its tentacles. Captured prey is bent toward the mouth and swallowed whole.
Under good conditions it buds new individuals from the body wall. Sexual reproduction with eggs and sperm occurs when conditions become less favorable.
It is listed as Least Concern. Its remarkable regenerative ability makes it important in studies of development and aging.
