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Caves EM, Sutton TT, Warrant EJ, Johnsen S. Measures and models of visual acuity in epipelagic and mesopelagic teleosts and elasmobranchs. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:807-826. [PMID: 37572152 PMCID: PMC10465391 DOI: 10.1007/s00359-023-01661-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/12/2023] [Accepted: 07/19/2023] [Indexed: 08/14/2023]
Abstract
Eyes in low-light environments typically must balance sensitivity and spatial resolution. Vertebrate eyes with large "pixels" (e.g., retinal ganglion cells with inputs from many photoreceptors) will be sensitive but provide coarse vision. Small pixels can render finer detail, but each pixel will gather less light, and thus have poor signal relative-to-noise, leading to lower contrast sensitivity. This balance is particularly critical in oceanic species at mesopelagic depths (200-1000 m) because they experience low light and live in a medium that significantly attenuates contrast. Depending on the spatial frequency and inherent contrast of a pattern being viewed, the viewer's pupil size and temporal resolution, and the ambient light level and water clarity, a visual acuity exists that maximizes the distance at which the pattern can be discerned. We develop a model that predicts this acuity for common conditions in the open ocean, and compare it to visual acuity in marine teleost fishes and elasmobranchs found at various depths in productive and oligotrophic waters. Visual acuity in epipelagic and upper mesopelagic species aligned well with model predictions, but species at lower mesopelagic depths (> 600 m) had far higher measured acuities than predicted. This is consistent with the prediction that animals found at lower mesopelagic depths operate in a visual world consisting primarily of bioluminescent point sources, where high visual acuity helps localize targets of this kind. Overall, the results suggest that visual acuity in oceanic fish and elasmobranchs is under depth-dependent selection for detecting either extended patterns or point sources.
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Affiliation(s)
- Eleanor M Caves
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Tracey T Sutton
- Department of Marine and Environmental Sciences, Halmos College of Arts and Sciences, Nova Southeastern University, Dania Beach, FL, 33004, USA
| | - Eric J Warrant
- Department of Biology, Lund University, Biology Building, Sölvegatan 35, Lund, Sweden
| | - Sönke Johnsen
- Department of Biology, Duke University, Durham, NC, 27708, USA
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Ryan LA, Slip DJ, Chapuis L, Collin SP, Gennari E, Hemmi JM, How MJ, Huveneers C, Peddemors VM, Tosetto L, Hart NS. A shark's eye view: testing the 'mistaken identity theory' behind shark bites on humans. J R Soc Interface 2021; 18:20210533. [PMID: 34699727 PMCID: PMC8548079 DOI: 10.1098/rsif.2021.0533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Shark bites on humans are rare but are sufficiently frequent to generate substantial public concern, which typically leads to measures to reduce their frequency. Unfortunately, we understand little about why sharks bite humans. One theory for bites occurring at the surface, e.g. on surfers, is that of mistaken identity, whereby sharks mistake humans for their typical prey (pinnipeds in the case of white sharks). This study tests the mistaken identity theory by comparing video footage of pinnipeds, humans swimming and humans paddling surfboards, from the perspective of a white shark viewing these objects from below. Videos were processed to reflect how a shark's retina would detect the visual motion and shape cues. Motion cues of humans swimming, humans paddling surfboards and pinnipeds swimming did not differ significantly. The shape of paddled surfboards and human swimmers was also similar to that of pinnipeds with their flippers abducted. The difference in shape between pinnipeds with abducted versus adducted flippers was bigger than between pinnipeds with flippers abducted and surfboards or human swimmers. From the perspective of a white shark, therefore, neither visual motion nor shape cues allow an unequivocal visual distinction between pinnipeds and humans, supporting the mistaken identity theory behind some bites.
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Affiliation(s)
- Laura A Ryan
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
| | - David J Slip
- Taronga Conservation Society Australia, Bradley's Head Road, Mosman, New South Wales 2088, Australia
| | - Lucille Chapuis
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Enrico Gennari
- Oceans Research Institute, Mossel Bay 6500, South Africa.,South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa.,Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa
| | - Jan M Hemmi
- School of Biological Sciences and The UWA Oceans Institute, M092, University of Western Australia, Perth, Western Australia 6009, Australia
| | - Martin J How
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Charlie Huveneers
- College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Victor M Peddemors
- New South Wales Department of Primary Industries, Sydney Institute of Marine Science, Mosman, New South Wales 2088, Australia
| | - Louise Tosetto
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
| | - Nathan S Hart
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
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Mäthger LM, Zhao K, Herbst L. Photoreceptors in skate are arranged to allow for a broad horizontal field of view. J Comp Neurol 2021; 529:1184-1197. [PMID: 32840869 DOI: 10.1002/cne.25014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/27/2020] [Accepted: 08/05/2020] [Indexed: 11/10/2022]
Abstract
Studying retinal specializations offers insights into eye functionality and visual ecology. Using light microscopic techniques, including retinal whole-mounts, we investigated photoreceptor densities in the retina of the skate Leucoraja erinacea. We show that photoreceptors are not sized or oriented in the same way, and that they are not evenly distributed across the retina. There was a dorsally located horizontal visual streak with increased photoreceptor density, with additional local maxima in which densities were highest. Photoreceptors were longest and thinnest inside this visual streak, becoming shorter and thicker toward the periphery and toward the ventral retina. Furthermore, in the peripheral retinal parts, photoreceptors (particularly the outer segments) were noticeably tilted with respect to the retinal long axis. In order to understand how photoreceptors are tilted inside the eye, we used computerized tomography (CT) and micro-CT, to obtain geometrical dimensions of the whole skate eye. These CT/micro-CT data provided us with the outlines of the skate eye and the location of the retina and this enabled us to reconstruct how photoreceptors tilt in an intact eye. Findings were analyzed relative to previously published ganglion cell distributions in this species, showing a posteriorly located retinal area with photoreceptor: ganglion cell convergence as low as 39:1. Some peripheral areas showed ratios as high as 391:1. We frame our findings in terms of the animal's anatomy: body and eye shape, specifically the location of the tapetum, as well as the visual demands associated with lifestyle and habitat type. A speculative function in polarization sensitivity is discussed.
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Affiliation(s)
- Lydia M Mäthger
- Marine Biological Laboratory, Bell Center, Woods Hole, Massachusetts, USA
| | - Kevin Zhao
- Marine Biological Laboratory, Bell Center, Woods Hole, Massachusetts, USA.,Biological Sciences Division, University of Chicago, Chicago, Illinois, USA
| | - Lena Herbst
- Marine Biological Laboratory, Bell Center, Woods Hole, Massachusetts, USA.,Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
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Collin SP. Scene through the eyes of an apex predator: a comparative analysis of the shark visual system. Clin Exp Optom 2018; 101:624-640. [PMID: 30066959 DOI: 10.1111/cxo.12823] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/09/2018] [Accepted: 07/09/2018] [Indexed: 12/15/2022] Open
Abstract
The eyes of apex predators, such as the shark, have fascinated comparative visual neuroscientists for hundreds of years with respect to how they perceive the dark depths of their ocean realm or the visual scene in search of prey. As the earliest representatives of the first stage in the evolution of jawed vertebrates, sharks have an important role to play in our understanding of the evolution of the vertebrate eye, including that of humans. This comprehensive review covers the structure and function of all the major ocular components in sharks and how they are adapted to a range of underwater light environments. A comparative approach is used to identify: species-specific diversity in the perception of clear optical images; photoreception for various visual behaviours; the trade-off between image resolution and sensitivity; and visual processing under a range of levels of illumination. The application of this knowledge is also discussed with respect to the conservation of this important group of cartilaginous fishes.
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Affiliation(s)
- Shaun P Collin
- The Oceans Institute and the Oceans Graduate School, The University of Western Australia, Perth, Western Australia, Australia
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Fukudome M, Yamawaki Y. Head Movements During Visual Orienting Toward Moving Prey in the Lizard Takydromus tachydromoides. Zoolog Sci 2017; 34:468-474. [DOI: 10.2108/zs170045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Miyuki Fukudome
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Yoshifumi Yamawaki
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan
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Takiyama T, Hamasaki S, Yoshida M. Comparison of the Visual Capabilities of an Amphibious and an Aquatic Goby That Inhabit Tidal Mudflats. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:39-50. [PMID: 26967712 DOI: 10.1159/000443923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/08/2016] [Indexed: 11/19/2022]
Abstract
The mudskipper Periophthalmus modestus and the yellowfin goby Acanthogobius flavimanus are gobiid teleosts that both inhabit the intertidal mudflats in estuaries. While P. modestus has an amphibious lifestyle and forages on the exposed mudflat during low tide, the aquatic A. flavimanus can be found at the same mudflat at high tide. This study primarily aimed to elucidate the differential adaptations of these organisms to their respective habitats by comparing visual capacities and motor control in orienting behavior during prey capture. Analyses of retinal ganglion cell topography demonstrated that both species possess an area in the dorsotemporal region of the retina, indicating high acuity in the lower frontal visual field. Additionally, P. modestus has a minor area in the nasal portion of the retina near the optic disc. The horizontally extended specialized area in P. modestus possibly reflects the need for optimized horizontal sight on the exposed mudflat. Behavioral experiments to determine postural and eye direction control when orienting toward the object of interest revealed that these species direct their visual axes to the target situated below eye level just before a rapid approach toward it. A characteristic feature of the orienting behavior of P. modestus was that they aimed at the target by using the specialized retinal area by rotating the eye and lifting the head before jumping to attack the target located above eye level. This behavior could be an adaptation to a terrestrial feeding habitat in which buoyancy is irrelevant. This study provides insights into the adaptive mechanisms of gobiid species and the evolutionary changes enabling them to forage on land.
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Affiliation(s)
- Tomo Takiyama
- Graduate School of Biosphere Science, Hiroshima University, Hiroshima, Japan
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Takiyama T, Luna da Silva V, Moura Silva D, Hamasaki S, Yoshida M. Visual Capability of the Weakly Electric Fish Apteronotus albifrons as Revealed by a Modified Retinal Flat-Mount Method. BRAIN, BEHAVIOR AND EVOLUTION 2015; 86:122-30. [DOI: 10.1159/000438448] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/07/2015] [Indexed: 11/19/2022]
Abstract
Apteronotus albifrons (Gymnotiformes, Apteronotidae) is well known to have a sophisticated active electrosense system and is commonly described as having poor vision or being almost blind. However, some studies on this species suggest that the visual system may have a role in sensing objects in the environment. In this study, we investigated the visual capabilities of A. albifrons by focusing on eye morphology and retinal ganglion cell distribution. The eyes were almost embedded below the body surface and pigmented dermal tissue covered the peripheral regions of the pupil, limiting the direction of incoming light. The lens was remarkably flattened compared to the almost spherical lenses of other teleosts. The layered structure of the retina was not well delineated and ganglion cells did not form a continuous sheet of cell bodies. A newly modified retinal flat-mount method was applied to reveal the ganglion cell distribution. This method involved postembedding removal of the pigment epithelium of the retina for easier visualization of ganglion cells in small and/or fragile retinal tissues. We found that ganglion cell densities were relatively high in the periphery and highest in the nasal and temporal retina, although specialization was not so high (approx. 3:1) with regard to the medionasal or mediotemporal axis. The estimated highest possible spatial resolving power was around 0.57 and 0.54 cycles/degree in the nasal and temporal retina, respectively, confirming the lower importance of the visual sense in this species. However, considering the hunting nature of A. albifrons, the relatively high acuity of the caudal visual field in combination with electrolocation may well be used to locate prey situated close to the side of the body.
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Claes JM, Partridge JC, Hart NS, Garza-Gisholt E, Ho HC, Mallefet J, Collin SP. Photon hunting in the twilight zone: visual features of mesopelagic bioluminescent sharks. PLoS One 2014; 9:e104213. [PMID: 25099504 PMCID: PMC4123902 DOI: 10.1371/journal.pone.0104213] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/04/2014] [Indexed: 01/01/2023] Open
Abstract
The mesopelagic zone is a visual scene continuum in which organisms have developed various strategies to optimize photon capture. Here, we used light microscopy, stereology-assisted retinal topographic mapping, spectrophotometry and microspectrophotometry to investigate the visual ecology of deep-sea bioluminescent sharks [four etmopterid species (Etmopterus lucifer, E. splendidus, E. spinax and Trigonognathus kabeyai) and one dalatiid species (Squaliolus aliae)]. We highlighted a novel structure, a translucent area present in the upper eye orbit of Etmopteridae, which might be part of a reference system for counterillumination adjustment or acts as a spectral filter for camouflage breaking, as well as several ocular specialisations such as aphakic gaps and semicircular tapeta previously unknown in elasmobranchs. All species showed pure rod hexagonal mosaics with a high topographic diversity. Retinal specialisations, formed by shallow cell density gradients, may aid in prey detection and reflect lifestyle differences; pelagic species display areae centrales while benthopelagic and benthic species display wide and narrow horizontal streaks, respectively. One species (E. lucifer) displays two areae within its horizontal streak that likely allows detection of conspecifics' elongated bioluminescent flank markings. Ganglion cell topography reveals less variation with all species showing a temporal area for acute frontal binocular vision. This area is dorsally extended in T. kabeyai, allowing this species to adjust the strike of its peculiar jaws in the ventro-frontal visual field. Etmopterus lucifer showed an additional nasal area matching a high rod density area. Peak spectral sensitivities of the rod visual pigments (λmax) fall within the range 484–491 nm, allowing these sharks to detect a high proportion of photons present in their habitat. Comparisons with previously published data reveal ocular differences between bioluminescent and non-bioluminescent deep-sea sharks. In particular, bioluminescent sharks possess higher rod densities, which might provide them with improved temporal resolution particularly useful for bioluminescent communication during social interactions.
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Affiliation(s)
- Julien M. Claes
- Laboratoire de Biologie Marine, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
- * E-mail:
| | - Julian C. Partridge
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
- Neuroecology Group, School of Animal Biology and the UWA Oceans Institute, The University of Western Australia, Crawley, Australia
| | - Nathan S. Hart
- Neuroecology Group, School of Animal Biology and the UWA Oceans Institute, The University of Western Australia, Crawley, Australia
| | - Eduardo Garza-Gisholt
- Neuroecology Group, School of Animal Biology and the UWA Oceans Institute, The University of Western Australia, Crawley, Australia
| | - Hsuan-Ching Ho
- National Museum of Marine Biology and Aquarium, Checheng, Taiwan
- Institute of Marine Biodiversity and Evolutionary Biology, National Dong Hwa University, Shoufeng, Taiwan
| | - Jérôme Mallefet
- Laboratoire de Biologie Marine, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Shaun P. Collin
- Neuroecology Group, School of Animal Biology and the UWA Oceans Institute, The University of Western Australia, Crawley, Australia
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Muguruma K, Stell WK, Yamamoto N. A morphological classification of retinal ganglion cells in the Japanese catshark Scyliorhinus torazame. BRAIN, BEHAVIOR AND EVOLUTION 2014; 83:199-215. [PMID: 24642951 DOI: 10.1159/000358285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 12/31/2013] [Indexed: 11/19/2022]
Abstract
Retinal ganglion cells (GCs) in the Japanese catshark Scyliorhinus torazame were labeled retrogradely with biotinylated dextran amine (BDA3000). First the labeled cells were classified into 5 morphological types (types I-III: small GCs; types IV and V: large GCs) according to the size of the soma and the dendritic arborization pattern as seen in retinal wholemounts. Type I cells were stellate, with dendrites radiating in different directions. Type II cells had bipolar dendritic trees, with 2 primary dendrites extending in opposite directions. Type III cells had a single thick primary dendrite. Type IV cells were stellate, with dendrites covering a large area centered on the cell body. Type V cells were asymmetric, with most dendrites extending opposite to the axon as a large, fan-shaped dendritic field. Subsequently a wholemount was cross-sectioned, and we classified cells further into multiple subtypes according to the level of dendritic arborization within the inner plexiform layer. The present results suggest the existence of many types of GCs in elasmobranchs in addition to the 3 types of large GCs that have been characterized previously. Some of the newly described GC subtypes in the catshark retina appear to be similar to some of those reported in actinopterygians.
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Affiliation(s)
- Kaori Muguruma
- Laboratory of Fish Biology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Muguruma K, Takei S, Yamamoto N. Retinal Ganglion Cell Distribution and Spatial Resolving Power in the Japanese CatsharkScyliorhinus torazame. Zoolog Sci 2013; 30:42-52. [DOI: 10.2108/zsj.30.42] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Kaori Muguruma
- Laboratory of Fish Biology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Nagoya 464-8601, Japan
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Newman AS, Marshall JN, Collin SP. Visual Eyes: A Quantitative Analysis of the Photoreceptor Layer in Deep-Sea Sharks. BRAIN, BEHAVIOR AND EVOLUTION 2013; 82:237-49. [DOI: 10.1159/000355370] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 08/22/2013] [Indexed: 11/19/2022]
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Lisney TJ, Theiss SM, Collin SP, Hart NS. Vision in elasmobranchs and their relatives: 21st century advances. JOURNAL OF FISH BIOLOGY 2012; 80:2024-54. [PMID: 22497415 DOI: 10.1111/j.1095-8649.2012.03253.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This review identifies a number of exciting new developments in the understanding of vision in cartilaginous fishes that have been made since the turn of the century. These include the results of studies on various aspects of the visual system including eye size, visual fields, eye design and the optical system, retinal topography and spatial resolving power, visual pigments, spectral sensitivity and the potential for colour vision. A number of these studies have covered a broad range of species, thereby providing valuable information on how the visual systems of these fishes are adapted to different environmental conditions. For example, oceanic and deep-sea sharks have the largest eyes amongst elasmobranchs and presumably rely more heavily on vision than coastal and benthic species, while interspecific variation in the ratio of rod and cone photoreceptors, the topographic distribution of the photoreceptors and retinal ganglion cells in the retina and the spatial resolving power of the eye all appear to be closely related to differences in habitat and lifestyle. Multiple, spectrally distinct cone photoreceptor visual pigments have been found in some batoid species, raising the possibility that at least some elasmobranchs are capable of seeing colour, and there is some evidence that multiple cone visual pigments may also be present in holocephalans. In contrast, sharks appear to have only one cone visual pigment. There is evidence that ontogenetic changes in the visual system, such as changes in the spectral transmission properties of the lens, lens shape, focal ratio, visual pigments and spatial resolving power, allow elasmobranchs to adapt to environmental changes imposed by habitat shifts and niche expansion. There are, however, many aspects of vision in these fishes that are not well understood, particularly in the holocephalans. Therefore, this review also serves to highlight and stimulate new research in areas that still require significant attention.
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Affiliation(s)
- T J Lisney
- Department of Psychology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
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Collin SP. The Neuroecology of Cartilaginous Fishes: Sensory Strategies for Survival. BRAIN, BEHAVIOR AND EVOLUTION 2012; 80:80-96. [DOI: 10.1159/000339870] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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