POLYMORPHISM IN CNIDARIANS EBOOK DOWNLOAD

Cnidarian: Cnidarian, any member of phylum Cnidaria (Coelenterata), are polymorphic, differing in morphology (form and structure) and/or physiology. The body form of a cnidarian is constructed following two basic body plans, the polyp form and the medusa form. (Polymorphism). • Both forms have tentacles. Jump to Polymorphism - Polymorphism refers to the occurrence of structurally and functionally more than two different types of individuals within the same organism. It is a characteristic feature of Cnidarians, particularly the polyp and medusa forms, or of zooids within colonial organisms like those in ‎: ‎Cnidaria; ‎Hatschek‎,


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POLYMORPHISM IN CNIDARIANS EBOOK DOWNLOAD


These appear between or sometimes on top of the muscle cells.

POLYMORPHISM IN CNIDARIANS EBOOK DOWNLOAD

Sensory cells appear between or sometimes on polymorphism in cnidarians of the muscle cells, [9] and communicate via synapses gaps across which chemical signals flow with motor nerve cells, which polymorphism in cnidarians mostly between the bases of the muscle cells.

These are found between the bases of muscle cells. In some species it also contains low concentrations of cnidocytes, which are used to subdue prey that is still struggling.

POLYMORPHISM IN CNIDARIANS EBOOK DOWNLOAD

It is a characteristic feature polymorphism in cnidarians Cnidariansparticularly the polyp and medusa forms, or of zooids within colonial organisms like those in Hydrozoa. Cnidocytes[ edit ] These "nettle cells" function as harpoonssince their payloads remain connected to the bodies of the cells by threads.

Polymorphism in Coelenterata

Three types of cnidocytes are known: Most species have nematocysts. Ptychocysts are found only in the order Cerianthariatube anemones. Spirocysts do not have cilia. A tough capsule, the cnidawhich houses the thread, its polymorphism in cnidarians and a mixture of chemicals that may include venom or adhesives or both.

In hydrozoans, the polyp phase is more conspicuous than the medusa phase in groups such as hydroids and hydrocorals. Hydromedusae are smaller and more delicate than scyphomedusae or cubomedusae; they may polymorphism in cnidarians completely absent from the life cycle of some hydrozoan species.

Some other species produce medusae, but the medusae never separate themselves from the polyps. Cubozoans have medusae commonly known as box jellyfishfrom their shape.

Zoology info: POLYMORPHISM IN CNIDARIA

Some of these are polymorphism in cnidarians for human fatalities, mostly in tropical Australia and Southeast Asiaand include the so-called sea wasps. The polyp is tiny and inconspicuous. Sea wasp Chironex fleckeri. World Life Research Institute Many cnidarian polyps are individually no more than a millimetre or so across.

Polyps of most hydroids, hydrocorals, and soft and hard coralshowever, proliferate asexually into colonies, which polymorphism in cnidarians attain much greater size and longevity than their component polyps.

Polymorphism: Definition, Causes and Significance | Cnidarians

Certain tropical sea anemones class Anthozoa may be a metre in diameter, and some temperate ones are nearly that tall. Anthozoans are long-lived, both individually and as colonies; some sea anemones are centuries polymorphism in cnidarians. All medusae and sea anemones occur only as solitary individuals.

Scyphomedusae can weigh more than a ton, whereas hydromedusae are, at most, a few centimetres across.

Cnidaria - Wikipedia

polymorphism in cnidarians Tentacles of medusae, however, may be numerous and extensible, which allows the animals to influence a considerably greater range than their body size might suggest.

Large populations of hydroids can build up on docks, boats, and rocks. Similarly, some medusae attain remarkable densities—up to thousands per litre of water—but only for relatively brief periods.

POLYMORPHISM IN CNIDARIANS EBOOK DOWNLOAD