CLASSIFICATION OF MYXINE OR HAGFISH
Subphylum :- VERTEBRATA (Vertebral column present ).
Division :- Agnatha ( Jaws and paired appendages absent ).
Class :- Cyclostomata ( Mouth circular, suctorial, without jaws ).
Order :- Myxinoidea ( Mouth without funnel, with 8 tentacles. Gills 10 to 14 pairs. Branchial basket feebly developed ).
GENUS :- Myxine
GEOGRAPHICAL DISTRIBUTION
Myxine is distributed along seacoasts of the Atlantic and Pacific oceans in North European, North Atlantic, American and Japanese sea waters.
HABIT AND HABITAT
- Hagfishes or Myxine sometimes descend to a depth of 300 fathoms. They are purely marine, nocturnal and lie buried in the muddy bottom. They are parasitic or quasiparasitic and generally found attached to the body of fishes, especially around gill area. They bore their way into
host body to eat viscera and muscles.
GENERAL CHARACTERSTICS OF MYXINE OR HAGFISH
- Commonly called as hagfish or borer.
- Body is soft, without scales, worm-like, measuring about 60 cm in length and differentiated into head, trunk and tail.
- Anterior extremity contains four tentacles supported by skeletal rods.
- Mouth is terminal and surrounded by lips. Buccal funnel, and jaws are absent.
- There is a single nostril present close to the mouth. On ventrolateral sides mucous pores and distinct.
- Dorsal fin indistinct caudal tin and ventral fin confluents.
- Eyes vestigial, due to dark and bottom dwelling habit, photoreceptor organ is reduced.
- Secrete enormous mucus through mucous pores.
- 10 to 14 pairs of gills open into a branchial chamber, which opens to the exterior by a single branchial opening.
- Hermaphroditic and protandrous. Eggs are enclosed in horny shell, bearing hooks by which they attach themselves to the weeds.
ECONOMIC IMPORTANCE
- Hagfishes damage fish caught in nets. Sometimes hagfishes enter into the body of other fishes and eat entire soft parts leaving only a bag of skin and the bones.
SPECIAL FEATURES
In hagfishes same individual produces sperms and then eggs later on. Development is direct. The hagfishes are injurious to fish industry. They are important from evolutionary point of view. The evolution of jawed vertebrates from agnathans could be hypothesized as the latter needed only jaws. Although no direct link is available to understand evolution of gnathostomes, but some
armoured agnathan might have served as ancestor to the jawed vertebrates.
IDENTIFICATION
The animal has 4 tentacles, single gill aperture and no buccal funnel and above features, hence it is Myxine.
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