Image shows a juvenile Hydra at an advanced stage of budding from the "parent" Hydra.

Hydra

Phylum:   Cnidaria

Class: Hydrazoa (Coelenterates)

Hydra are one of the few commonly observed freshwater coelenterates.  They are found in unpolluted waters where they attach to aquatic vegetation, fallen leaves, and submerged stones.  They possess stinging cells called nematocysts.  These stinging cells are used to inject a numbing poison into microcrustaceans such as water fleas or other copepods that brush up against the Hydra's tentacles.  Hydra have five to eight tentacles that vary in length from species to species.  They range in colour from colourless to green or brown.  Hydra reproduce asexually by budding.

See also Hydra Culture Medium CM12

Click here to download care instructions (pdf, 0.1M, new window)

Download a movie file that shows a colony of hydra (some budding) as they feed on brine shrimp - opens in a new window, mp4 file, 2.5M, opens with QuickTime or iTunes (may be played on a video iPod).

Note:  The movie image has been enhanced (green contrast) for improved viewing.  The actual colour of these hydra was light brown.

Download the free Quicktime player

View details of student project:  A Study of Hydra vulgaris and the Effects of Melatonin on Heat Stress  (new window)