Difference Between Petromyzon and Myxine

The upcoming discussion will update you about the difference between petromyzon and myxine.

Difference # Petromyzon:

1. Live in rivers and seas.

2. A median, lobed dorsal fin and a tail fin.

3. Sensory structures in the complex, glandular, slimy, pigmented skin.

4. Buccal funnel present, surrounded with papillae.

5. Teeth many, yellow and horny. The tongue also bears horny teeth.

6. Eyes hidden and retarded in the larva, exposed and complete in the adult.

7. Seven pairs of gill pouches, opening directly to the exterior and less directly into the adult gullet.

8. A slight constriction indicates separa­tion of utricle and saccule, semicircular canals two.

9. The nostril unpaired, dorsal and ends blindly in the pituitary sac.

10. A velum guards the respiratory tube from the buccal cavity.

11. The intestine is without convolutions. Typhlosole in the form of a spiral valve present.

12. A urinogenital sinus and two genital pores.

13. Skull very imperfectly roofed.

14. Hints of vertebral arches, cartilagi­nous branchial basket round gill pouches.

15. All the components of the brain are distinct and well-marked.

16. Lateral line sense organs are not en­closed in a canal and exposed.

17. Sexes are separate.

18. Ova small and spherical.

19. Cleavage holobastic.

20. Development with a metamorphosis.

Difference # Myxine:

1. Exclusively marine.

2. The fin is confined to tail.

3. Numerous large glands present in the complex slimy skin.

4. Buccal funnel absent. The mouth is edged with tentacles supported by cartilage.

5. A single medial tooth and two rows of smaller teeth present on the tongue.

6. Eyes hidden and rudimentary.

7. Six pairs of gill pouches opening di­rectly into the gullet and less directly to the exterior.

8. Internal ear with a saccule and one semicircular canal.

9. The nostril large, unpaired, dorsal and opens into the pharynx through a pas­sage, the pituitary sac.

10. A velum separates the buccal cavity from the pharynx.

11. The intestine is very wide and bears longitudinal ridges.

12. No urinogenital sinus, only one geni­tal pore.

13. Skull without any roof.

14. Skeletal system less developed, only a hint of a branchial basket.

15. Cerebrum and cerebellum rudimen­tary.

16. Lateral line sense organs absent.

17. Protandrous hermaphrodite.

18. Ova large and oval with attaching threads.

19. Cleavage meroblastic in Bdellostoma.

20. Development direct in Bdellostoma.