Genus Hydra Linnaeus, 1758

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External Links

• Hydra Linnaeus, C. 1758. Systema naturae per regna tria naturae, secundem classes, ordines, genera, species, cum characteribus, differentis, synonymis, locis. Editio decima, reformata. Holmiae : Laurentii Salvii Vol. 1 10, 824 pp.

Introduction

Hydras are the most characteristically recognised Hydrozoans in Australia. They are found in a variety of colours including; green, brown, white, grey, tan or red. Their body plan is simple - a tubular body, a disc attached to the substrate, and a circle of three to eight tentacles containing nematocysts (stinging cells) used for defence and feeding. The mouth at the centre of the tentacle structure is the only opening to the gut cavity, so food is taken in and waste expelled from the same cavity.

There are 81 hydra records compiled on the World Register of Marine Species (WoRMS), there are likely many more, presently two are described from Australia:

Hydra oligactis Pallas, 1766
Hydra hexactinella von Lendenfeld, 1886

Distribution

Extra Distribution Information

Ubiquitous throughout Australia.

Ecological Descriptors

Freshwater.

History of changes