Three other features sometimes considered to be diagnostic of Cnidaria are radial symmetry and planula and polyp stages in development, but all are problematic. Excretion by … 1.34D), Helipora, Telesto, Tubipora (organ-pipe coral) (Fig. The male medusa makes sperm, whereas the female medusa makes eggs. Diagnostic Features of Phylum Cnidaria 3. However, the development of organs or organ systems is not advanced in this phylum. ii. Invertebrate Zoology - Exam 1 - Phylum Cnidaria. Coelenteron is undivided and without stomodaeum. These animals are usually cylindrical in shape and are attached to a substrate. Sea anemones are car­niv­o­rous polyps that are quite large, rang­ing up to 200mm in length. 1) Spongiaria 2) Cnidaria and 3)Ctenophora. The classification of Cnidarians by Parker and Haswell or as revised by Marshall and Williams, 1972 (7th edn. Body has more than two cell layers, tissues and organs. vi. Diagnostic features – Hydrozoans (Phylum Cnidaria) are small, predatory animals, most of which are marine, but a few live in fresh water. Symmetry: radially symmetrical; Grade of organization: tissue grade of organization. 2. Etymology: Cnidaria-Greek : knide, nettle. Diagnostic Features of Phylum Nematoda 3. Cnidarians contain specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts (stingers). An example is the colonial hydroid called an Obelia. This group includes free living or … Systematic Resume. Definition of Phylum Platyhelminthes: Triploblastic, acoelomate, un-segmented and bilaterally symmetrical metazoans, without anus, circulatory system, but with a mouth, protonephridial system, parenchyma tissues within the space between the body wall and the gut, and spiral cleavage development. The sessile form of Obelia geniculate has two types of polyps: gastrozooids, which are adapted for capturing prey, and gonozooids, which bud to produce medusae asexually. The four major diagnostic features of the phylim mollusca are: visceral mass, foot, mantle, and shell. 1.32C), Valella (Fig. These coiled threads release toxins into the target and can often immobilize prey or scare away predators. xi. In 1888, Hatschek splitted Leuckart’s Coelenterata into 3 dis­tinct phylum: Spongiaria (Porifera), Cnidaria and Coelenterata. About 9,000 species known. They tend to be brightly col­ored. Privacy Policy3. v. Extending between the stomodaeum and the body-wall there are mesenteries. viii. Purestock / Getty Images. Usually two siphonoglyphs are present. 1.32A), Porpita{Fig. The phylum has the following distinguishing characteristics: These are pore-bearing multicellular animals. What are the main taxonomic features of phylum cnidaria? Characteristic Features of Phylum Platyhelminthes: 1. Hyman regarded ctenophora as a separate phylum. iii. The outer tissue layer, called the ectoderm or epidermis, includes cnidocytes—the distinctive diagnostic feature of the phylum. Phylum Cnidaria is also known as Phylum Coelenterata. Sea anemones are usually brightly colored and can attain a size of 1.8 to 10 cm in diameter. 1.34C), Pennatula (Sea-pen) (Fig. In terms of cellular complexity, cnidarians show the presence of differentiated cell types in each tissue layer, such as nerve cells, contractile epithelial cells, enzyme-secreting cells, and nutrient-absorbing cells, as well as the presence of intercellular connections. Mesogloea separates these two layer This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. Unit 9 Phylum Cnidaria 60-62 Unit10 Phylum Platyhelminthes 63-66 ... Know the diagnostic features of the Eubacteria, C) Know the differences between the gram positive and gram negative bacteria. v. 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