Comparative light microscopic studies on the retina of some elasmobranch fishes.

Kohbara, Jun; Niwa, Hiroshi; Oguri, Mikio

doi:10.2331/suisan.53.2117

Cited by 16 publications

(14 citation statements)

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“…The photoreceptor cells and the characterisation of rods and cones of wobbegong sharks are similar in morphology to other elasmobranch species [Kohbara et al, 1987;see Hart et al, 2006 for review;Litherland and Collin, 2008]. Rods were numerous throughout the light micrographs and easily identified by their long, cylindrical outer segments.…”

Section: Discussionmentioning

confidence: 76%

“…Cones were less prevalent and were distinguished by their short, conical outer segments, their large inner segments and the presence of a nucleus that is more sclerad than the nuclei of the rods. These characteristics are seen in the cone cells of other elasmobranch species as well [Kohbara et al, 1987;Collin, 1988;Braekevelt, 1992Braekevelt, , 1994bLogiudice and Laird, 1994]. Large horizontal cells have previously been reported in the elasmobranchs retina Gruber and Cohen, 1985;Collin, 1988] and although a detailed analysis was not performed, it's probable that both species have at least 2 morphological types of horizontal cells.…”

Section: Discussionmentioning

confidence: 90%

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Interspecific Visual Adaptations among Wobbegong Sharks (Orectolobidae)

2010

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Several visual traits have previously been assessed in elasmobranchs; however, few studies have examined and compared multiple visual attributes within a particular genus. The primary advantage of studying closely related species is that any differences between them are more likely to reflect functional ecological adaptations rather than the effects of phylogenetic separation. In this study, the visual capabilities of 4 wobbegong shark species, which vary in life-history and/or habitat, were examined: the western wobbegong (Orectolobus hutchinsi), the spotted wobbegong (O. maculatus), the ornate wobbegong (O. ornatus) and the dwarf spotted wobbegong (O. parvimaculatus). The retinae of all 4 wobbegong species are duplex; rod and cone photoreceptors can be distinguished easily on the basis of morphology. Some variation in relative eye size exists, with O. parvimaculatus possessing the largest eyes. The topographic distribution of cells within the ganglion cell layer of O. hutchinsi reveals a weakly elongated central visual streak of increased cell density, mediating a higher spatial resolving power of 2.06 cycles deg^–1 in the frontal visual field. Retinal topography of O. maculatus and O. parvimaculatus is similar, with both possessing a dorsal horizontal streak facilitating an increased spatial resolving power of 3.51 cycles deg^–1 and 3.91 cycles deg^–1, respectively, in the lower visual field. O. parvimaculatus also possesses an area of increased cell density in the naso-ventral region of the retina, mediating acute vision in the upper caudal region of the visual field. While all 4 species have visual systems optimised for increased visual sensitivity, O. maculatus and O. parvimaculatus appear to be particularly well suited to activity under low light conditions.

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 90%

Interspecific Visual Adaptations among Wobbegong Sharks (Orectolobidae)

2010

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“…The morphology of photoreceptors in a range of species have shown that rods are primarily distinguished by their long cylindrical inner and outer segments and cones have much shorter conical outer segments and wider, tapering inner segments [Kato, 1962;Stell, 1972;Stell and Witkovsky, 1973;Ali and Anctil, 1974;Toyoda et al, 1978;Gruber and Cohen, 1985;Kohbara et al, 1987;Braekevelt, 1992Braekevelt, , 1994Logiudice and Laird, 1994;Bozzano et al, 2001]. Cones are most abundant in the retinae of predominantly shallow-dwelling, diurnally active species, such as the giant shovelnose ray Rhinobatos batillum (= typus ) [Collin, 1988] and the great white shark Carcharodon carcharias [Gruber and Cohen, 1985], and least abundant in nocturnal or deep-dwelling species, such as the birdbeak dogfish Deania calcea [Kohbara et al, 1987] and the piked dogfish Squalus acanthias [Stell, 1972].…”

Section: Photoreceptors In Cartilaginous Fishes: Evolution Of Dim-ligmentioning

confidence: 99%

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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“…A light microscopic examination of the retina in the 5 deep-sea shark species revealed an arrangement of cellular layers similar to that found in other elasmobranch species [Gruber, 1977;Kohbara et al, 1987;Hart et al, 2004Hart et al, , 2006Litherland et al, 2009] and more broadly in other vertebrate species [Dowling, 1970]. One notable exception is that, when compared with terrestrial vertebrates, the photoreceptors in the adult elasmobranch retina constitute about half of the retinal thickness [Gruber, 1977].…”

Section: Adaptations In Retinal Morphologymentioning

confidence: 59%

“…Sharks are no exception and studies of the morphology of photoreceptors have revealed that the majority of species possess a duplex retina containing both rod and cone photoreceptors [Kato, 1962;Stell, 1972;Stell and Witkovsky, 1973;Gruber et al, 1975;Gruber and Cohen, 1985;Kohbara et al, 1987;Sillman et al, 1996;Schieber et al, 2012], with the exception of some deepdwelling species whose retinae appear to have lost their cones and contain only morphologically rod-like receptor cells [Kohbara et al, 1987;Bozzano et al, 2001;Bozzano, 2004]. Among the species possessing a duplex retina, the ratio of cones to rods is highly variable, ranging from 1: 4 in the great white shark, Carcharodon carcharias [Gruber et al, 1975], to 1: 100 in the deeper dwelling smooth dogfish, Mustelus canis [Stell and Witkovsky, 1973]; however, it is important to note that the ratio of photoreceptors is by no means spatially consistent across the photoreceptor layer.…”

Section: Introductionmentioning

confidence: 99%

Visual Eyes: A Quantitative Analysis of the Photoreceptor Layer in Deep-Sea Sharks

Marshall

Collin

2013

Brain Behav Evol

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The marine environment presents unique visual challenges for a range of organisms, particularly those dwelling at great depths, where sunlight may either be absent or drop to very low levels. Under these environmental conditions, the visual system must maximise light absorption in order to enhance the detection of prey, predators and potential mates. Using stereological analysis of retinal wholemounts, the distribution and number of photoreceptors (rods) was determined for 5 deep-sea shark species from a range of depths (46-1,500 m). All species possessed areas of increased photoreceptor density (with peaks between 41,000 and 82,000 rods/mm²) within discrete regions of the retina. The total number of rods in the photoreceptor layer also varied between 17 × 10⁶ and 63 × 10⁶. It is evident that increasing sensitivity of the retina is an important adaptation to life in the deep sea. The location of discrete areas of high cell density within the photoreceptor layer of the retina corresponds to discrete areas of the visual field that are sampled at a higher intensity, hence increasing sensitivity. The location of these areas of increased sensitivity differed between the species of this study. The disparity of areas of increased sensitivity seen between species is thought to reflect distinctive predator avoidance and prey capture strategies. This study reveals that the visual demands of deep-sea sharks vary interspecifically and that sampling of each species' visual field is not solely determined by its habitat.

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Comparative light microscopic studies on the retina of some elasmobranch fishes.

Cited by 16 publications

References 0 publications

Interspecific Visual Adaptations among Wobbegong Sharks (Orectolobidae)

Interspecific Visual Adaptations among Wobbegong Sharks (Orectolobidae)

Evolution and Ecology of Retinal Photoreception in Early Vertebrates

Visual Eyes: A Quantitative Analysis of the Photoreceptor Layer in Deep-Sea Sharks

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