Tissue Development: Phylum Cnidaria

Cnidarians (from the Greek knide meaning nettle) re largess the next higher catch of organization of animals. They ar radially symmetric and possess strong tissues. However, like sponges, cnidarians arrive only two germ layers: exoderm and endoderm. A middle layer, called mesoglea, is largely composed of a thick material. Hydra, jellyfish, sea anem whizs, and coral colonies belong to this diverse group. Members of this phylum, which consists of about 10 000 species, are set up exclusively in aquatic ecosystems. The agreeable majority reside in marine environments and are vernacular along Canadas three shorelines. Fewer than 50 species arouse be found in freshwater ecosystems, hydra being angiotensin-converting enzyme of the most commonly occurring cnidarians in our lakes and ponds. The evolutionary advances that the cnidarians demonstrate compared with the comminuted complex sponges can be attributed to the development of true tissues. Cnidarians present specialized nerve, muscle, and digestive tissues. A nerve net encircles their body. slightly of the free-swimming forms have a ring of nerve cells more or less the bell, perhaps the primitive beginning of a central loathsome system. If hydra or sea anemones are touched, they respond by flattening out and pulling their tentacles inward. This type of heading indicates coordination of nerves and muscles, something non seen in the primitive sponge. Cnidarians capture food by development specialized cells called cnidocytes, which digest sacs known as nematocysts.

The nematocysts contain coiled, hollow, filamentlike tubes th at can shoot out rapidly and infiltrate the! shinny of a prey or predator, some injecting nephrotoxic material. If sufficient nematocysts are triggered, the target can be paralyzed. Thousands of nematocysts can be found on a single tentacle. Beach-goers may have painful memories of toxin-laden nematocysts. Thousands of the stinging cells can be found along the tentacles of jellyfish and floating bell-shaped colonies. The purple-colored medusa, or Vellela, occasionally floats... If you exigency to get a full essay, order it on our website: BestEssayCheap.com

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