The eyes in three genera of hagfish (Eptatretus, paramyxine andMyxine)—A case of degenerative evolution

@article{Fernholm1975TheEI,
  title={The eyes in three genera of hagfish (Eptatretus, paramyxine andMyxine)—A case of degenerative evolution},
  author={B Fernholm and Kaj Holmberg},
  journal={Vision Research},
  year={1975},
  volume={15},
  pages={253-IN4}
}

First Fossil Hagfish (Myxinoidea): A Record from the Pennsylvanian of Illinois

  • D. Bardack
  • Geography, Environmental Science
    Science
  • 1991
TLDR
A fossil hagfish (Myxinoidea), a new genus from the Pennsylvanian, shows tentacles, structures of the head skeleton and internal organs, and it is quite similar to its recent relatives.

The Cyclostome Retina

TLDR
Hagfishes and lampreys are vertebrates classified systematically as Agnatha (jawless) or Cyclostomata (round-mouths) but most research on retinas of vertebrates has been carried out on species which belong to the gnathostomes and this has led to generalizations which are not always valid for the agnaths.

A New Species of Hagfish (Myxinidae: Eptatretus) Associated with Deep-Sea Coral Habitat in the Western North Atlantic

TLDR
Eptatretus lopheliae is a small hagfish species observed, videotaped, and caught in close association with Lophelia pertusa reef habitat off the southeastern United States.

Vertebrate features revealed in the rudimentary eye of the Pacific hagfish (Eptatretus stoutii)

TLDR
Hagfish eyes are degenerate but not degenerating, i.e. rudimentary but growing Retinal interneurons discovered implying ancestral hagfish had derived retinas & vision; this data clarify Agnathan retinal homologies, reveal characters that now appear to be ubiquitous across the eyes of vertebrates, and refine interpretations of early vertebrate visual system evolution.

Comparative retinal morphology of the platypus

TLDR
Evaluation of opsins indicates that red and blue immunoreactive cone opsins, but not rhodopsin, are present in the most basal of the extant species examined, the Pacific hagfish, establishing emergence of this pigment in an extant relative of tetrapods.

The Lateral Line System of Hagfishes (Craniata: Myxinoidea)

TLDR
It is concluded that most or all eptatretid hagfish possess a lateral line system composed of shallow trenches, or grooves, lined with a single class of flask-shaped receptive cells, representing the primitive condition for craniate lateral line organs.

Conodonts: A Sister Group to Hagfishes?

TLDR
The fossil record of the conodont animal is almost exclusively represented in the fossil record by the phosphatic elements of the feeding apparatus, which was the only mineralized component of the skeleton.

Gonads and Reproduction in Hagfishes

TLDR
The GnRH-like system of myxinoids is considered as a possible homologue of the caudal neuromodula-tory GnRH system of higher vertebrates and indications for the production of steroids by the gonads have been brought forth.

Hagfish embryos again: the end of a long drought.

  • N. Holland
  • Biology
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2007
TLDR
Because hagfish embryos should now be available on a regular basis, the way is open for additional morphological and developmental genetic investigations to help evaluate existing evolutionary scenarios and perhaps suggest new ones.

Physiological adaptations of the living agnathans

TLDR
Differences in the oxygen dissociation curves of ammocoetes, adult lampreys and hagfishes can be related to differences in the characteristics of their monomeric haemoglobins and their environments and modes of life.
...

References

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Les yeux des Cyclostomes fossiles et le problème de l'origine des Myxinoïdes

TLDR
Evidence is offered that osteostracan possessed spheroidal eyeballs similar to those of present-day petromyzontids; also, that heterostracans were equipped with conical eyeballs closely conforming to those encountered in the recent myxinoid Eptatretus burgeri.

On the light sensitivity of the Atlantic hagfish, Myxine glutinosa, maintained against a white background under continuous illumination.

  • K. Holmberg
  • Environmental Science
    General and comparative endocrinology
  • 1971