Coelenterata : General Characters and Example , Multiple Choice questions: NEET
🌑Coelenterata : Defination
These are multi cellular aquatic animal with tissue grade level of organisation having gastro vascular cavity.
🌑General characters
🔴They are aquatic, mostly marine, sessile or free-swimming animals.
🔴They are Diploblastic, Acoelomate, radially symmetrical animal with tissue grade level of organisation.
🔴They are also called as Cnidaria.The word cnidarian has been taken from the Cnidoblasts or cnidocytes.
🔴Cnidoblasts contain the stinging capsules called as nematocysts which are present on the tentacles and the body.
🔴Cnidoblasts are used for the anchorage, defense and for the capture of prey.
🔴Cnidarians have a central gastro-vascular cavity or Coelenteron with a single opening called mouth on hypostome.
🔴Digestion is extracellular and intracellular.
🔴Some of the cnidarians are called as corals because they have a skeleton composed of calcium carbonate.
🔴Cnidarians also have two basic stage in their life cycle called polyp and medusa .
🔴The polyp Is a sessile and cylindrical form like Hydra, Adamsia whereas, the Medusa is umbrella-shaped and free-swimming like Aurelia or jelly fish.
🔴Metagenesis is alternation of generation between polyp and Medusa in cnidarians.
🔴Polyps reproduce asexually by budding and form medusae.
🔴Medusae form sperm and egg sexually and form the polyps through the Fertilization externally.
🌑Examples of Coelentrata🌑 Physalia🔴It is commonly called as Portuguese man of war.🔴It is marine neuston animal because it always float in ocean.🔴During floating, it look like a warship therefore it is called as Portuguese man of war.🔴It has pneumatophore which can be seen on water surface while floating and rest of body are submerged in water.🔴Pneumatophores are composed of units called zooids which may be gonozooids and gastrozooids. These zooids may have tentacles.
🔴It is commonly called as sea Pen or Sea feather.
🔴Body is divided into distal rachis and peduncle.
🔴Rachis has fleshy branches with a series of 8 to 12 gastrozooids.
🔴It is sedentary and colonial animal and found in deep sea and prefer warm water.
🔴Gastrozooids are feeding zooids and form gamete also Siphonozooids draw water current
🔴It is found in United States at St. Lawrence to Carolina and also common in Europe.
🔴It is commonly called as sea Fan.
🔴It is a salt water invertebrate and can be identified by its purple color tissue and it's fan shape body.
🔴It's skeleton is made up of Collagen derivative compound called as Gorgonin and Calcite.
🔴It is tube like polyp and protrude from needle like Spicules.
🔴Gorgonia is sessile , Immobile and Colonial Animal and found to be attached with the surface.
🔴It is found in sea coast of West indies , Atlantic ocean and Madras Coast.
🔴It is commonly called as Brain Coral because it's shape resemble with the human brain.
🔴It is a colonial coelenterate and look like polyp and secrete hard skeleton of calcium carbonate therefore called as stony coral.
🔴They use their tentacles to catch prey and as a defense organ.
🔴Brain Coral reproduce asexually through buffing of polyp and sexually by sperm and egg .
🔴It is found in shallow warm water in coral reef through out the world like indo Pacific coast and Gulf of Mexico.
1. The Coelenterates are mostly marine, aquatic and
3. The term cnidaria is used for the Coelenterates due to having
5. The term cnidaria is used for the Coelenterates due to having
7. In Cnidarian, gastro vascular cavity is present with
10. Consider the following statement and select the correct code:
11 . In which of the following Coelenterates, polyp and Medusa make alternation of generation as Metagenesis.
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