IDENTIFICATION (with reason) OF Metridium sp. (B.Sc. ZOOLOGY_CCF-CC5_SEM4)

  Identifying features are:

1. Multicellular heterotroph.
2. embryonic development, preceded by heterogametic fertilization.

            Hence, the specimen belongs to the Kingdom Animalia.

1. Soft-bodied, polymorphic mesozoa with radial and biradial symmetry.
2. Ectoderm & endoderm separated by a noncellular mesoglea.
3. Single gastrovascular cavity.
4. Polypoid zooids which possess single body cavity,the coelenteron, with a solitary mouth.
5. Mouth is guarded by a circlet of tentacles.
6. Outer body wall possesses numerous cnidoblasts (or cnidocytes).

                  Hence, the specimen belongs to the Phylum Cnidaria.

1. Only polypoid forms are present.
2. Stomodaeum is present with a pair of siphonoglyphs.
3. Pharynx is a hanging tube inside gastrovascular cavity.
4. Marginal tentacles around mouth.
5. Mesoglea acts as connective tissue.
6. Presence of mesentries.

            Hence, the specimen belongs to the Class Anthozoa.

1. Tentacles are numerous, simple ,branched & hollow.
2. Mesentries may be complete or incomplete.
3. Tentacles & mesentries are in hexamerous cycles.
4. Usually with two siphonoglyphs.

              Hence, the specimen belongs to the Sub Class Hexacorallia.

1. Short,cylindrical body,divided into pedal disc,column & oral disc.
2. Pedal disc for attachment to the substratum.
3. cylindrical column.
4. Slit-shaped mouth at the centre of oral disc.
5. Mouth leads into short gullet with siphonoglyphs.
6. Mouth is surrounded by many short & conical tentacles in 5 or 6 circles.

    Hence, the specimen seems to be Metridium sp.

Systematic Position (Ruppert & Barnes 1994)

 Kingdom: Animalia

   Phylum: Cnidaria

     Class: Anthozoa

         SubClass: Hexacorallia

            Genus: Metridium