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| Hagfish | |
|---|---|
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| Pacific hagfish resting on bottom 280 m depth off Oregon coast | |
| Scientific classification | |
| Kingdom: | |
| (unranked): | |
| Superclass: | |
| Class: | Myxini |
| Order: | Myxiniformes |
| Family: | Myxinidae |
Hagfish are craniates in the superclass Cyclostomata, class Myxini. Hagfish do not have a skeleton, except they do have a skull, which is made of cartilage.
Because of this, many researchers think Myxini should not be in the subphylum Vertebrata. However, because of its fins and gills, they are called fish. They are marine, meaning they live in the sea.
The original 19th century classification groups hagfish and lampreys together as cyclostomes (or historically, Agnatha), as the oldest surviving class of vertebrates alongside gnathostomes . An alternative scheme proposed that jawed vertebrates are more closely related to lampreys than to hagfish, so vertebrates include lampreys but exclude hagfish.
