Classification of Hydra – the Phylum Cnidaria
#Hydra meaning how to#
Finally, you will also learn where and how to collect a hydra for your microscopic project. We will also see what happens to a sick hydra. I will show you several interesting behaviors when a hydra feeds or move. In this article, you will learn about this fantastic creature in detail: by definition, classification, and cellular structure. Upon contact with prey, the contents of the stinging cells are explosively discharged, firing stings that can paralyze small animals.īiologists are especially interested in hydra because of their remarkable regenerative ability – they do not appear to die of old age, or to age at all. Each tentacle is clothed with many stinging cells. These tentacles can greatly extend to catch the prey or use for locomotion. Hydra is characterized by its tentacles around the mouth opening. This is why the hydra is often mistaken for a plant or alga. Typically, hydras remain attached to some underwater objects, waving their tentacles slowly with the current. It is visible to the naked eyes when fully extended. Hydra has a cylindrical, radially symmetric body from 2 to 20 mm in length. Hydra is a genus of tiny fresh-water organisms that are classified under the phylum of Cnidaria.
Hydras have been known to feed on the organic material of the substrate when the food supply is insufficient. The organism is then taken in through the mouth, which is star-shaped or circular. This is considered the key mechanism in digestion. The prey is brought to the mouth (proctostome) by the tentacles, a response that is induced glutathione. Hydra capture their food by paralyzing and killing the food organism by means of nematocysts, which are discharged into the prey. Hydra oligactis, as in all Cnidaria, are strictly carnivorous and eat many different kinds of small metazoans, including annelids, copepods, cladocerans, and insects. In general, the behavior is characterized by its mechanical nature, great independence of parts, lack of integration, and lack of exact responses. When there is an insufficient supply of oxygen, hydras move to regions of higher oxygen content. The hydras usually move by looping and somersaulting, by attaching the tentacle ends and pulling themselves along.
#Hydra meaning free#
Free hydras can move from place to place by basal gliding. For no apparent reason, contractions and expansions of the body occur at intervals and the tentacles are constantly in motion. When the hydra remains undisturbed, its body is extended and the tentacles spread. The brown hydra rarely is found at depths exceeding 1.5 m.
Hydras attach to stones, twigs, vegetation, or debris. Following unfavorable conditions, such as injuries or periods of scarce resources, hydras occasionally reproduce through transverse and longitudinal fission. Buds are produced every two to three days under favorable conditions. The bud then pinches off and a new individual becomes independent. The bud begins as a hemispherical outpouching that eventually elongates, becomes cylindrical, and develops tentacles. Buds originate at the junction of the stalk and gastric regions.
The common asexual method of reproduction by hydras is budding. Hydras are are well known as the faunas of ponds, spring brooks, unpolluted streams, rivers, and the littoral zone of lakes. The brown hydra is commonly found in the Northern Hemisphere and parts of Australia.
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