IDENTIFICATION (with reason) OF Petromyzon 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. Functional jaws are absent.
2. Paired fins are absent.

          Hence, the specimen belongs to the Super Class: Agnatha

1. Circular & suctorial mouth.
2. Presence of 1-16 pairs of gill slits.
3. Nostril is single & median.

       Hence, the specimen belongs to the Class: Cyclostomata

1. Seven pairs of round gill openings are present.
2. Branchial basket is complete.
3. Presence of one or two dorsal fins.

Hence, the specimen belongs to the Order: Petromyzontia

1. Long, cylindrical eel like smooth body.
2. Tail is laterally compressed.
3. Presence of a paired eyes covered by transparent skin.
4. Upper lip highly developed & forms a buccal funnel.
5. Tongue rasping.
6. Mouth at the bottom of the buccal funnel.
7. Buccal funnel is beset with many horny teeth.
8. Two median dorsal fins are almost equal in dimensions.

Hence, the specimen seems to be Petromyzon sp.

Systematic Position: (Young,1981)

Kingdom: Animalia

         Phylum: Chordata

             Sub Phylum: Vertebrata

                    Super Class: Agnatha

                         Class: Cyclostomata

                              Order: Petromyzontia

                                  Genus: Petromyzon