Hydra oligactis

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Hydra oligactis
Scientific classification
Kingdom: Animalia Phylum: Cnidaria Class: Hydrozoa Order: Hydroida Family: Hydridae Genus: Hydra Species: H. oligactis
Binomial name
Hydra oligactis Pallas, 1766

Hydra oligactis, also known as the brown Hydra, is a species of hydra found widely dispersed in the northern temperate zone. It is a common organism found in still waters from early Spring to late Autumn.

It is commonly found attached to the stems of water plants, the undersides of leaves , submerged twigs and on the surface of stones. When disturbed it retracts to a small brown blob which is easly overlooked. Gently sweeping through a clean weedy pond and allowing the collected water and leaves to stand in a jar will often reveal Hydra emerging after only a few minutes.

When in feeding mode, the fully extended tentacles are very long and may exceed 1 inch (25 mm) in length. In this condition the tentacles are very difficult to see with the naked eye and are often only revealed when a prey animal such as Daphnia is caught.