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Hydra viridissima is commonly called green hydra due to its coloration, which is due to the symbiotic green algae Chlorella vulgaris which live within its body. [3] These creatures are typically 10 mm long and have tentacles that are about half of their length. [ 4 ]
Like other hydras, Hydra vulgaris cling to a base object with a "foot" pad, shaped like a disk. The Hydra moves by releasing its grip on its base and is carried away by the current. H. vulgaris can also move by bending over, grabbing a surface with its tentacles, releasing its grip with its "foot" and flipping over itself.
Hydra (/ ˈ h aɪ d r ə / HY-drə) is a genus of small freshwater hydrozoans of the phylum Cnidaria.They are native to the temperate and tropical regions. [2] [3] The genus was named by Linnaeus in 1758 after the Hydra, which was the many-headed beast of myth defeated by Heracles, as when the animal has a part severed, it will regenerate much like the mythical hydra's heads.
The relative length of the tentacles compared to the body is characteristic of the species and serves to differentiate it from any other brown Hydra of cool temperate waters. When a cold sensitive strain of H. oligactis is subjected to temperature stress, it undergoes a shift from asexual budding to sexual reproduction. [2]
Just prior to host spawning, Polypodium everts to the normal position of cell layers, revealing tentacles scattered along the stolon. [2] During eversion, the yolk of the host oocyte fills the gastral cavities of the parasite, supplying the future free-living stage with nutrients. [2] [8] The parasitic phase of its life cycle usually takes ...
In the class Hydrozoa, the polyps are indeed often very simple, like the common little fresh water species of the genus Hydra. Anthozoan polyps, including the corals and sea anemones, are much more complex due to the development of a tubular stomodaeum leading inward from the mouth and a series of radial partitions called mesenteries. Many of ...
Hydrozoa (hydrozoans; from Ancient Greek ὕδωρ (húdōr) 'water' and ζῷον (zôion) 'animal') is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water.
Marine worms vary in size from microscopic to over 1 metre (3.3 ft) in length for some marine polychaete worms (bristle worms) [42] and up to 58 metres (190 ft) for the marine nemertean worm (bootlace worm). [43]