An adipose eyelid is a transparent eyelid found in some species of fish, that covers some or all of the eye.[1][2][3] They are most commonly found on deep sea (benthic) fish, but can also be seen on non-benthic fish. Fish with this feature include milkfish, isospondyls (including herring), jacks, mullets, and mackerel.[4][5] The overall anatomy of the eyelids plays an important role in understanding their possible purpose.
Though the true purpose of these bodily structures is not known, it is generally accepted that the eyelids play some role in affecting the vision of the fish or otherwise serving to protect the fish. There are four proposed theories.
The eyelid may act as a lens, increasing the fish's ability to focus on specific objects and interpreting its surroundings better.[4]
It may provide the fish the capability of seeing polarized light.
It may block out ultraviolet light.
It may serve as a physical barrier against foreign objects in the waters.[4]
Scientists are still unsure of the biological implications for the second theory. The first theory is more practical because of the presence of this feature on deep sea fish. This ability to see better is crucial for their survival as visibility is severely reduced in the deeper parts of the ocean. The opposite however can be said for the non-benthic fish because there is more light near the surface of the ocean, so there would not necessarily be a need for a stronger sense of sight.[6]
AnatomyEdit
Most adipose eyelids are separated into anterior and posterior parts, commonly referred to as layers.[4][6] These layers also vary in number, anywhere from three to five, depending on the fish. The layers are arranged in a parallel fashion, relative to the dorsal fin to the fish's belly. This arrangement makes for eyelids that are optically positive, meaning that a certain amount and type of light will be able to enter the eye. The eyelids also are able to filter out certain wavelengths of light and have different refractive indices for light. The skin of the eyelid is the thinnest over the eyeballs and begins to thicken as it moves on to the cheek and face of the fish.[4]
Epithelial tissue and connective tissue formed from several fibers of collagen are the main components of these layers. In some fish, there are three layers, with the middle layer being made of connective tissue, which helps to bind the other two epithelial layers together.
Filter specificsEdit
One special detail about adipose eyelids is their ability to filter out specific wavelengths of light.[6][7] For example, different fish have a different concentration of epithelial tissue in their eyelids. However, there is a range that most of the eyelids will filter. Most adipose eyelids can filter out light that has a wavelength shorter than 305 nanometers. Another fact is that these eyelids can also reflect light and this level of reflection corresponds to polarization of the light and the angle at which it is shone. To test for these ranges, different fish eyelids were exposed to light generated from photometers and polarizing microscopes.[6]
^"Teleost Anatomy Ontology: Adipose eyelid". National Center for Biomedical Ontology. Retrieved 2011-12-11.
^. Smithsonian Tropical Research Institute. Archived from the original on 2010-06-25. Retrieved 2011-12-11.
^ abcdeChang, C.-H.; Chiao, C.-C.; Yan, H. Y. (2009). "The structure and possible functions of the milkfish Chanos chanos adipose eyelid". Journal of Fish Biology. 75 (1): 87–99. doi:10.1111/j.1095-8649.2009.02266.x. PMID 20738484.
^Rangaswamy, C. P. "On the Development of Adipose Eyelids in the Fry of Liza Microlepis and L. Parsia". Indian Journal of Fisheries: 223–6.
^ abcdStewart, Kenneth W. (1962). "Observations on the Morphology and Optical Properties of the Adipose Eyelid of Fishes". Journal of the Fisheries Research Board of Canada. 19 (6): 1161–2. doi:10.1139/f62-076.
^Denton, E. J.; Nicol, J. A. C. (1965). "Polarization of light reflected from the silvery exterior of the bleak, Alburnus alburnus". Journal of the Marine Biological Association of the United Kingdom. 45 (3): 705–9. doi:10.1017/S0025315400016532. Archived from the original on 2012-07-14.
October 19, 2023
adipose, eyelid, adipose, eyelid, transparent, eyelid, found, some, species, fish, that, covers, some, they, most, commonly, found, deep, benthic, fish, also, seen, benthic, fish, fish, with, this, feature, include, milkfish, isospondyls, including, herring, j. An adipose eyelid is a transparent eyelid found in some species of fish that covers some or all of the eye 1 2 3 They are most commonly found on deep sea benthic fish but can also be seen on non benthic fish Fish with this feature include milkfish isospondyls including herring jacks mullets and mackerel 4 5 The overall anatomy of the eyelids plays an important role in understanding their possible purpose Contents 1 Purpose 2 Anatomy 2 1 Filter specifics 3 ReferencesPurpose EditThough the true purpose of these bodily structures is not known it is generally accepted that the eyelids play some role in affecting the vision of the fish or otherwise serving to protect the fish There are four proposed theories The eyelid may act as a lens increasing the fish s ability to focus on specific objects and interpreting its surroundings better 4 It may provide the fish the capability of seeing polarized light It may block out ultraviolet light It may serve as a physical barrier against foreign objects in the waters 4 Scientists are still unsure of the biological implications for the second theory The first theory is more practical because of the presence of this feature on deep sea fish This ability to see better is crucial for their survival as visibility is severely reduced in the deeper parts of the ocean The opposite however can be said for the non benthic fish because there is more light near the surface of the ocean so there would not necessarily be a need for a stronger sense of sight 6 Anatomy EditMost adipose eyelids are separated into anterior and posterior parts commonly referred to as layers 4 6 These layers also vary in number anywhere from three to five depending on the fish The layers are arranged in a parallel fashion relative to the dorsal fin to the fish s belly This arrangement makes for eyelids that are optically positive meaning that a certain amount and type of light will be able to enter the eye The eyelids also are able to filter out certain wavelengths of light and have different refractive indices for light The skin of the eyelid is the thinnest over the eyeballs and begins to thicken as it moves on to the cheek and face of the fish 4 Epithelial tissue and connective tissue formed from several fibers of collagen are the main components of these layers In some fish there are three layers with the middle layer being made of connective tissue which helps to bind the other two epithelial layers together Filter specifics Edit One special detail about adipose eyelids is their ability to filter out specific wavelengths of light 6 7 For example different fish have a different concentration of epithelial tissue in their eyelids However there is a range that most of the eyelids will filter Most adipose eyelids can filter out light that has a wavelength shorter than 305 nanometers Another fact is that these eyelids can also reflect light and this level of reflection corresponds to polarization of the light and the angle at which it is shone To test for these ranges different fish eyelids were exposed to light generated from photometers and polarizing microscopes 6 References Edit Froese Rainer Adipose eyelid FishBase Glossary Retrieved 2011 12 11 Teleost Anatomy Ontology Adipose eyelid National Center for Biomedical Ontology Retrieved 2011 12 11 Smithsonian Tropical Research Institute Shorefishes of the Tropical Eastern Pacific Smithsonian Tropical Research Institute Archived from the original on 2010 06 25 Retrieved 2011 12 11 a b c d e Chang C H Chiao C C Yan H Y 2009 The structure and possible functions of the milkfish Chanos chanos adipose eyelid Journal of Fish Biology 75 1 87 99 doi 10 1111 j 1095 8649 2009 02266 x PMID 20738484 Rangaswamy C P On the Development of Adipose Eyelids in the Fry of Liza Microlepis and L Parsia Indian Journal of Fisheries 223 6 a b c d Stewart Kenneth W 1962 Observations on the Morphology and Optical Properties of the Adipose Eyelid of Fishes Journal of the Fisheries Research Board of Canada 19 6 1161 2 doi 10 1139 f62 076 Denton E J Nicol J A C 1965 Polarization of light reflected from the silvery exterior of the bleak Alburnus alburnus Journal of the Marine Biological Association of the United Kingdom 45 3 705 9 doi 10 1017 S0025315400016532 Archived from the original on 2012 07 14 Retrieved from https en wikipedia org w index php title Adipose eyelid amp oldid 1062056262, wikipedia, wiki, book, books, library,
