Phylum Cnidaria (Obelia sp. )

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GALLERY 

Obelia sp 








obelia sp















jellyfish 
obelia sp structure 
jellyfish 
Actinia sp. 








INTERESTING FACTS 

  • Obelia is a genus in the class Hydrozoa, which consists of mainly marine and some freshwater animal species and have both the polyp and medusa stages in their life cycle. 
  • The genus belongs to the phylumCnidaria, which are all aquatic and mainly marine organisms that are relatively simple in structure. It is also called sea fur.  
  • Cnidarians were the first animals to have muscles and nerves to produce behavior.
  •  They were also the first to have a mouth and stomach to digest food.  We learn about nematocysts when we watch an anemone catching a goby and two anemones fighting.
  • Cnidarians come in various body shapes and have different ways of living. 
  • Corals are cnidarians that build reefs.
  •  One anemone, Stomphia, can swim away from predators by contracting its entire body. The jellyfish body plan is like an anemone that has been turned upside down and a diverse group of cnidarians thrives at all depths of the ocean.

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classification 

  1. class hydrozoa   
  • eg ;eg; obelia sp 
    2. class Scphozoa 
  • eg; jellyfish
  • Scyphozoans usually display a four-part symmetry and have an internal gelatinous material called mesoglea
  • have no durable hard parts, including no head, no skeleton, and no specialized organs for respiration or excretion
  • The mouth opens into a central stomach, from which four interconnected diverticula radiate outwards
  • The nervous system usually consists of a distributed net of cells, although some species possess more organised nerve rings.
    3. class Anthozoa 
  • eg; Actinia sp.
  • The basic unit of the adult is the polyp;
  • consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles.
  • Anthozoans are carnivores, catching prey with their tentacles
  • The body wall consists of an epidermal layer, a jellylike mesogloea layer and an inner gastrodermis

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