The modern taxonomy is a lovely mess, with all new evolutionary and molecular biology studies that are slowly leading to subvert the old groups based on morphological similarities and replacing them with relatively superficial classifications that reflect more the reality of evolutionary history. Generally Myxini or hagfishes, agnates vertebrates are considered, but some do not consider them even vertebrates. It is certainly a group of chordates that are much more primitive than all other vertebrates, and usually are confused with the hagfishes lampreys, which in turn confused with real fish - in fact I do not think that is a valid clade, but only a hodgepodge of different groups of vertebrates superficially similar. But I digress. The tender hagfishes are sea creatures eel with spinal cord and cranial cartilage, small eyes and primitive sensory barbels, laterally flattened tail and pink-gray skin. They feed on fish, usually dead or dying, and being free of the jaws, to be able to pull out pieces of flesh from his body limp prey form a sort of knot that squeeze more and more to force his head back with a bite, which grasp with a sort of fleshy tongue is covered with sharp teeth. The hagfishes are particularly known to secrete at defensive purposes, huge amounts of extremely viscous transparent gelatinous mucus, the secretion is so fast you can fill up a bucket of mucus from 20 liters in minutes. Given their efforts to present itself as a nasty bites, usually not used for human consumption, except for one particular species that is appreciated in Korea but you know, eat all those parts. Bon Appetit! (Or whatever the spelling).
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