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

Fernholm, Bo; Holmberg, Kaj

doi:10.1016/0042-6989(75)90215-1

Cited by 58 publications

(56 citation statements)

References 9 publications

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“…These stages are illustrated in figure 1 , where the sequential acquisition of morphological features in the ascidian larval ocellus [Eakin and Kuda, 1971;Imai and Meinertzhagan, 2007], the hagfish eye [Kobayashi, 1964;Holmberg, 1970Holmberg, , 1971Holmberg, , 1977Fernholm and Holmberg, 1975;Locket and Jorgenson, 1998], the lamprey pineal organ [Pu and Dowling, 1981;Samejima et al, 1989;Ekström and Meissl, 2003], the lamprey retina [Holmberg, 1977;Govardovskii and Lychakov, 1984;Collin et al, 1999Collin et al, , 2003aCollin and Potter, 2000;Collin and Trezise, 2004;Davies et al, 2007a] and jawed vertebrates (gnathostomes) appear to form an evolutionary timeline. In each case, the membrane that contains the visual pigment extends from a cilium to form an outer segment, where there is a gradual transition towards a highly organized laminar structure.…”

Section: Ancestral Photoreceptorsmentioning

confidence: 99%

“…Despite their simple structure, hagfish photoreceptors are none-the-less vertebrate-like with an inner and outer segment and a mitochondria-rich ellipsoid [Fernholm and Holmberg, 1975;Locket and Jorgensen, 1998]. Although no retractile myoid is present, a distinct synaptic region contains synaptic vesicles.…”

Section: Photoreceptors In Hagfishes: Visual or Non-visual Light Detementioning

confidence: 99%

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Evolution and Ecology of Retinal Photoreception in Early Vertebrates

Collin¹

2010

Brain Behav Evol

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Visual ecology or the relationship between the visual system of an animal and its environment has proven to be a crucial research field for establishing general concepts of adaptation, specialization and evolution. The visual neuroscientist is indeed confronted with a plethora of different visual characteristics, each seemingly optimised for each species’ ecological niche, but often without a clear understanding of the evolutionary constraints at play. However, before we are able to fully understand the influence(s) of ecology and phylogeny on visual system design in vertebrates, it is first necessary to understand the basic bauplan of key representatives of each taxa. This review examines photoreception in hagfishes, lampreys, cartilaginous fishes and lungfishes with an eye to their ecology using a range of neurobiological methods including anatomy, microspectrophotometry and molecular genetics. These early vertebrates represent critical stages in evolution and surprisingly possess a level of visual complexity that is almost unrivalled in other vertebrates.

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Section: Ancestral Photoreceptorsmentioning

confidence: 99%

Section: Photoreceptors In Hagfishes: Visual or Non-visual Light Detementioning

confidence: 99%

Evolution and Ecology of Retinal Photoreception in Early Vertebrates

Collin¹

2010

Brain Behav Evol

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“…Hagfish eyes 39 are small, conical, completely lacking in any sign of a lens, an iris, a cornea or intra-or extraocular muscles, and buried beneath unpigmented translucent skin 39,40 . The retina contains only two main nuclear layers, with no obvious bipolar or amacrine cells, and the photoreceptors connect directly to the output neurons (ganglion cells) 36,[41][42][43] .…”

Section: The Hagfish Eyementioning

confidence: 99%

“…A smooth transition of features from stage to stage is apparent, compatible with the sequential acquisition of these features in ancestral forms. The stages we have illustrated are: the ascidian larva ocellus 58,77 , the hagfish eye 36,[39][40][41][42][43] , the lamprey pineal organ 48,78,79 , the lamprey retina 36,[80][81][82][83][84][85] and the jawedvertebrate retina.…”

Section: The Evolution Of Ciliary Photoreceptorsmentioning

confidence: 99%

Evolution of the vertebrate eye: opsins, photoreceptors, retina and eye cup

2007

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Charles Darwin appreciated the conceptual difficulty in accepting that an organ as wonderful as the vertebrate eye could have evolved through natural selection. He reasoned that if appropriate gradations could be found that were useful to the animal and were inherited, then the apparent difficulty would be overcome. Here, we review a wide range of findings that capture glimpses of the gradations that appear to have occurred during eye evolution, and provide a scenario for the unseen steps that have led to the emergence of the vertebrate eye.

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“…The skin of the head is continuous over the eyes and forms a more or less distinct eyespot due to a lack of pigmentation in the area just above the eyes. In other species (Myxinidae), the eyes are lo cated deep within the head and are covered by layers of muscle [for more detail, see Fernholm and Holmberg, 1975].…”

Section: Some Functional Considerationsmentioning

confidence: 99%

Retinofugal and Retinopetal Projections in the Pacific Hagfish, <i>Eptatretus stouti </i>(Myxinoidea) (Part 2 of 2)

Wicht¹,

Northcutt²

1990

Brain Behav Evol

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The retinofugal and retinopetal connections of the Pacific hagfish were determined using the fluorescent compound DiI as an in vitro tracer. The retinofugal connections were found to be bilateral and to reach preoptic;, thalamic and pretectal, as well as tectal, targets. No distinct basal optic root was found. A retinopetal projection in hagfishes is described here for the first time. It originates from two cell groups in the rostral mesencephalic tegmentum. These retinal connections in hagfishes are compared to the organization of the visual system in the second Recent group of jawless fishes, the lampreys. Both visual systems are similar in the number and location of the targets of retinal fibers. Furthermore, there is a striking similarity in the retinopetal systems. Major differences are found in the organization of the optic tract. These observations allow the identification of some cell groups not previously recognized in myxinoid brains or interpreted differently. Finally, the findings are discussed in relation to visually guided behavior in hagfishes.

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

Cited by 58 publications

References 9 publications

Evolution and Ecology of Retinal Photoreception in Early Vertebrates

Evolution and Ecology of Retinal Photoreception in Early Vertebrates

Evolution of the vertebrate eye: opsins, photoreceptors, retina and eye cup

Retinofugal and Retinopetal Projections in the Pacific Hagfish, <i>Eptatretus stouti </i>(Myxinoidea) (Part 2 of 2)

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