Guardian Nature School Team Contact Blog Project Noah Facebook Project Noah Twitter

A worldwide community photographing and learning about wildlife

Join Project Noah!
nature school apple icon

Project Noah Nature School visit nature school

Freshwater Hydra

Phylum Cnidaria, Class Hydrozoa


Barely macroscopic, about .5mm long, white. Photo taken at 10x magnification w/ compound light microscope, image being projected onto classroom SMARTboard.


Hydra are common in freshwater ponds and slow-moving streams. Some hydra possess zooxanthellae (symbiotic algae). This species does not appear to.


This specimen was found in one of my Corydoras catfish breeding tanks, attached to a piece of gravel. Upon closer inspection, there were several dozen, spread out on the gravel & one side of the tank glass. The tank does have a healthy population of Ulothrix algae - I assume that the hydra originated with the algae culture. It is unusual to spot one w/ the naked eye in a tank.

Species ID Suggestions

Sign in to suggest organism ID

1 Comment

BlueFerns 13 years ago

Wonderful documentation. thanks for all the information!

Spotted by

Hartford, Connecticut, USA

Spotted on Mar 4, 2011
Submitted on Mar 6, 2011

Related Spottings

Leeches Velvet worm Earthworm sponge

Nearby Spottings

Common Pond Snail Spotting Wood Betony Orb Weaver
Noah Guardians
Noah Sponsors
join Project Noah Team

Join the Project Noah Team