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Zoology
DIFFERENCES BETWEEN PETROMYZON (LAMPREY) AND MYXINE (HAGFISH)
By BS MediaTwitter Profile | Updated: Wednesday, 28 June 2017 12:15 UTC
Myxine (Hagfish) | Petromyzon (Lamprey) |
1. Hag fishes are scavengers. They penetrate into the dead fishes bodies and eat the tissues. | 1. They are semi parasitic. But the Larvae(Ammocoetes) leads an independent life. |
2. The body is. slender & eel-like | 2. The body is cylindrical & stout. |
3. They are exclusively marine habitats. | 3. These live in both in sea water and fresh water. They migrate into the rivers for spawning. |
4. the caudal fin is small. | 4. The caudal fin is well developed. |
5. The dorsal fin is not fully developed. | 5. The dorsal fin is divided into two portions by a notch. |
6. Mouth is terminal in position. It is surrounded by soft lips. Buccal funnel is absent. | 6. Mouth is sub-terminal in position. Buccal funnel is present. |
7. Single nostril is present very near to the mouth. | 7. Single nostril Is on the dorsal side of head region. |
8. Skull has no roof. | 8. Skull roc is incomplete. |
9. Small teeth are present on the tongue in two rows. | 9. Horny teeth are present in the buccal funnel and on the tongue. |
10. Salivary glands are present. | 10. Paired salivary glands are present |
11. The gill pouch number varies from six to fifteen pairs. | 11. There are seven pairs gill- pouches present. All these open Into the respiratory tube. |
12. Each aortic ‘arch supplies the hemibranch of a single gill pouch. | 12. Each aortic arch divides and the branches enter the posterior hemibranch of the nearby gill pouch. |
13. Brain is degenerated. | 13. Brain is well developed. |
14. Only thee pairs of cranial nerves are present. | 14. Ten pairs of cranial nerves are present |
15. Non functional paired eyes are burned in the skin. | 15. Paired functional eyes are present. |
16. Penial eye is absent. | 16. Penial eye is present. |
17. In the adult pronephros is retamed. But the functional kidney Is of mesonephric type and simple. | 17. The functional adult kidney is mesonephric type. |
18. Urinogenital sinus is not seen. | 18. Urinogenital sinus is formed. |
19. Sexes are united - Hermaphrodite. The anterior part of the gonad acts as ovary & the posterior part act Like Testis. | |
20. The eggs are large and covered by cylindrical horny shell. | 20. The eggs are small and are not covered by horny shell. |
21. The development is direct. | 21. Development is indirect. Arnmocoetes larva occurs in the life-history. |
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