#Hydra animal free

level 2 – interconnected ganglion cells synapsed to epithelial or motor cells.

level 1 – sensory cells or internal cells and,.

The structure of the nerve net has two levels: Nerve nets connect sensory photoreceptors and touch-sensitive nerve cells located in the body wall and tentacles. Hydra does not have a recognizable brain or true muscles. The nervous system of Hydra is a nerve net, which is structurally simple compared to more derived animal nervous systems. Respiration and excretion occur by diffusion throughout the surface of the epidermis, while larger excreta are discharged through the mouth. If the Hydra is sliced into many segments then the middle slices will form both a 'head' and a 'foot'. When a Hydra is cut in half, each half will regenerate and form into a small Hydra the 'head' will regenerate a 'foot' and the 'foot' will regenerate a 'head'. Hydras have two significant structures on their body: the 'head' and the 'foot'. These stem cells will continually renew themselves in the body column. A single Hydra is composed of 50,000 to 100,000 cells which consist of three specific stem cell populations that will create many different cell types. Hydramacin is a bactericide recently discovered in Hydra it protects the outer layer against infection. The cells making up these two body layers are relatively simple. The outer layer is the epidermis, and the inner layer is called the gastrodermis, because it lines the stomach. The layers are separated by mesoglea, a gel-like substance. Hydra has two main body layers, which makes it ' diploblastic'. This can paralyze the prey, especially if many hundreds of nematocysts are fired. Upon contact with prey, the contents of the nematocyst are explosively discharged, firing a dart-like thread containing neurotoxins into whatever triggered the release.

At the narrow outer edge of the cnidocyte is a short trigger hair called a cnidocil. Cnidocytes contain specialized structures called nematocysts, which look like miniature light bulbs with a coiled thread inside. Each tentacle, or cnida (plural: cnidae), is clothed with highly specialised stinging cells called cnidocytes.

#Hydra animal free

Gland cells in the basal disc secrete a sticky fluid that accounts for its adhesive properties.Īt the free end of the body is a mouth opening surrounded by one to twelve thin, mobile tentacles. Hydra has a tubular, radially symmetric body up to 10 mm (0.39 in) long when extended, secured by a simple adhesive foot known as the basal disc. Schematic drawing of a discharging nematocyst Biologists are especially interested in Hydra because of their regenerative ability they do not appear to die of old age, or to age at all. They are native to the temperate and tropical regions. Hydra ( / ˈ h aɪ d r ə/ HY-drə) is a genus of small, freshwater organisms of the phylum Cnidaria and class Hydrozoa. * Hydra salmacidis Lang da Silveira et al., 1997.* Hydra madagascariensis Campbell, 1999.* Hydra intermedia De Carvalho Wolle, 1978.