About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 31. Chapters: Anaspida, Heterostraci, Myxinidae, Osteostraci, Petromyzontiformes, Pituriaspida, Pteraspidomorphi, Thelodonti, Hagfish, Lamprey, List of prehistoric jawless fish, Agnatha, Black hagfish, Cyclostomata, Galeaspida, Cephalaspidomorphi, Haikouichthys, Jamoytius kerwoodi, Cephalaspis, Eptatretus, Myxine glutinosa, Furcacauda, Ostracoderm, Pacific hagfish, Inshore hagfish, Astraspis, Eptatretus bischoffii, Errivaspis, Arandaspis, Pteraspis, Pituriaspis doylei, Doryaspis, Auchenaspis, Hyperoartia, Alainaspis, Sacabambaspis, Hemicyclaspis, Endeiolepis, Drepanaspis gemuendenensis, Tremataspis, Ateleaspis, Boreaspis, Benneviaspidida, Arandaspida, Psammosteidae, Southern hagfish, Thelodus, New Zealand hagfish, Neeyambaspis, Lepidaspis, Pharyngolepis, Gulf hagfish, Caribbean Hagfish, Eptatretus strickrotti, Stroinolepis, Dartmuthia, Pycnosteus, Ctenaspis, Eriptychiida, Sphenonectris, Thyestes, Protaspididae, Astraspida, Cometicercus, Cornuata, Phlebolepis, Drepanolepis, Birkenia, Lasanius, Nochelaspis, Witaaspis, Rhyncholepis, Procephalaspis, Tesseraspis. Excerpt: Hagfish are marine craniates of the class Agnatha or Myxini, also known as Hyperotreti. Some researchers regard Myxini as not belonging to the subphylum Vertebrata. That is, they are the only living animals that have a skull but not a vertebral column. Despite their name, there is some debate about whether they are strictly fish (as there is for lampreys), since they belong to a much more primitive lineage than any other group that is placed in the category of fish (Chondrichthyes and Osteichthyes). The earliest fossil record dates back approximately 550 million years, or earlier to the Lower Cambrian period. Their unusual feeding habits and slime-producing capabilities have led members of the scientific community and popular media to dub the hagfish as the most "dis...
