IDENTIFICATION (with reason) OF Tetradon sp (B.Sc. ZOOLOGY_CCF- SEMESTER5_DSCC-9)

   Identifying features are:

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

            Hence, the specimen belongs to the Kingdom Animalia.

1. Presence of hollow, dorsal, tubular nerve cord.
2. Presence of notochord, at any stage of their life or throughout the life.
3.  Presence of pharyngeal gill slits & post anal tail during some stage in the ontogeny.

            Hence, the specimen belongs to the Phylum Chordata.

1. Presence of Cranium.
2. Presence of vertebral column.
3. Presence of paired lateral appendages.
4. A post anal tail usually present.

           Hence, the specimen belongs to the Sub Phylum: Vertebrata

1. Mouth is covered by functional jaws.
2. Presence of paired appendages.

       Hence, the specimen belongs to the Super Class Gnathostomata

1. Operculum is present to cover the gills.
2. Homocercal type of tail is present.
3. Presence of bony endoskeleton.
4. Presence of terminal mouth.

      Hence, the specimen belongs to the Class: Osteichthyes

1. Fins are  supported by lepidotrichia—thin, bony, or horny spines that radiate from the body.
2. Fin rays attach directly to the internal skeletal elements (radials).
3. Rays are connected by a thin layer of skin (webbing), acting like a folding fan. 

   Hence, the specimen belongs to the Sub Class: Actinopterygii

1. Scales are absent or covered by epidermis.
2. Presence of fully filamentous gills.
3. Presence of swim bladder.

Hence, the specimen belongs to the Super Order Teleostei

1. The dorsal and anal fins are almost always divided into two distinct sections: an anterior (front) portion supported by stiff, unsegmented spines and a posterior (back) portion composed of soft, branched rays.
2. Thoracic Pelvic Fins, usually consist of one spine and five soft rays.
3. Body is covered with rough ctenoid scales.
4. They possess highly protractible upper jaws (premaxilla) that can slide forward to create a vacuum-like suction, allowing them to effectively draw in and capture prey.

Hence, the specimen belongs to the  Order Perciformes

1. Fusion of the jaw bones (premaxilla and maxilla) into a powerful, beak-like structure. Four dental plates (two upper, two lower) are found.
2. Gill Openings are reduced.
3. Skin is either leathery and tough, or covered in modified scales that take the form of) small prickles (in pufferfish),
4. The pelvic fins and the pelvic girdle are either completely absent or reduced to a single rudimentary spine. Additionally, they lack anal fin spines.

Hence, the specimen seems to be 

Tetradon sp 

Systematic Position: (Young,1981)

Kingdom: Animalia

         Phylum: Chordata

             Sub Phylum: Vertebrata

                    Super Class: Gnathostomata

                         Class: Osteichthyes

                               Sub Class: Actinopterygii

                                  Super Order:Teleostei

                                              Order: Perciformes

                                                  Genus: Tetradon