Retinal Topography in Two Species of Baleen Whale (Cetacea: Mysticeti)

2018 ◽  
Vol 92 (3-4) ◽  
pp. 97-116 ◽  
Author(s):  
Thomas J. Lisney ◽  
Shaun P. Collin
Keyword(s):  
Ganglion Cells ◽  
Feeding Strategy ◽  
Visual Fields ◽  
Humpback Whale ◽  
High Density ◽  
Resolving Power ◽  
Temporal Area ◽  
Baleen Whales ◽  
Axial Diameter ◽  
Retinal Topography

Little is known about the visual systems of large baleen whales (Mysticeti: Cetacea). In this study, we investigate eye morphology and the topographic distribution of retinal ganglion cells (RGCs) in two species of mysticete, Bryde’s whale (Balaenoptera edeni) and the humpback whale (Megaptera novaeanglia). Both species have large eyes characterised by a thickened cornea, a heavily thickened sclera, a highly vascularised fibro-adipose bundle surrounding the optic nerve at the back of the eye, and a reflective blue-green tapetum fibrosum. Using stereology and retinal whole mounts, we estimate a total of 274,268 and 161,371 RGCs in the Bryde’s whale and humpback whale retinas, respectively. Both species have a similar retinal topography, consisting of nasal and temporal areas of high RGC density, suggesting that having higher visual acuity in the anterior and latero-caudal visual fields is particularly important in these animals. The temporal area is larger in both species and contains the peak RGC densities (160 cells mm–2 in the humpback whale and 200 cells mm–2 in Bryde’s whale). In the Bryde’s whale retina, the two high-density areas are connected by a weak centro-ventral visual streak, but such a specialisation is not evident in the humpback whale. Measurements of RGC soma area reveal that although the RGCs in both species vary substantially in size, RGC soma area is inversely proportional to RGC density, with cells in the nasal and temporal high-density areas being relatively more homogeneous in size compared to the RGCs in the central retina and the dorsal and ventral retinal periphery. Some of the RGCs were very large, with soma areas of over 2,000 µm2. Using peak RGC density and eye axial diameter (Bryde’s whale: 63.5 mm; humpback whale: 48.5 mm), we estimated the peak anatomical spatial resolving power in water to be 4.8 cycles/degree and 3.3 cycles/degree in the Bryde’s whale and the humpback whale, respectively. Overall, our findings for these two species are very similar to those reported for other species of cetaceans. This indicates that, irrespective of the significant differences in body size and shape, behavioural ecology and feeding strategy between mysticetes and odontocetes (toothed whales), cetacean eyes are adapted to vision in dim light and adhere to a common “bauplan” that evolved prior to the divergence of the two cetacean parvorders (Odontoceti and Mysticeti) over 30 million years ago.

scholarly journals Eye Morphology and Retinal Topography in Hummingbirds (Trochilidae: Aves)

2015 ◽  
Vol 86 (3-4) ◽  
pp. 176-190 ◽  
Author(s):  
Thomas J. Lisney ◽  
Douglas R. Wylie ◽  
Jeffrey Kolominsky ◽  
Andrew N. Iwaniuk
Keyword(s):  
Visual Fields ◽  
High Density ◽  
Resolving Power ◽  
Transverse Diameter ◽  
Density Region ◽  
Temporal Area ◽  
Eye Morphology ◽  
Neuron Density ◽  
Retinal Topography ◽  
Central High

Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ∼45,000 cells·mm-2, and a temporal area with lower densities (38,000-39,000 cells·mm-2). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cycles·degree-1. Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects.

Eye growth in sharks: Ecological implications for changes in retinal topography and visual resolution

2009 ◽  
Vol 26 (4) ◽  
pp. 397-409 ◽  
Author(s):  
LENORE LITHERLAND ◽  
SHAUN P. COLLIN ◽  
KERSTIN A. FRITSCHES
Keyword(s):  
Ganglion Cell ◽  
Spatial Resolution ◽  
Ganglion Cells ◽  
Feeding Strategy ◽  
Resolving Power ◽  
Foraging Strategies ◽  
Sandbar Shark ◽  
Topographic Analysis ◽  
Eye Growth ◽  
Topographic Distribution

AbstractThe visual abilities of sharks show substantial interspecific variability. In addition, sharks may change their habitat and feeding strategy throughout life. As the eyes of sharks continue to grow throughout the animal’s lifetime, ontogenetic variability in visual ability may also occur. The topographic analysis of the photoreceptor and ganglion cell distributions can identify visual specializations and assess changes in visual abilities that may occur concurrently with eye growth. This study examines an ontogenetic series of whole-mounted retinas in two elasmobranch species, the sandbar shark, Carcharhinus plumbeus, and the shortspine spurdog, Squalus mitsukurii, to identify regional specializations mediating zones for improved spatial resolution. The study examines retinal morphology and presents data on summation ratios between photoreceptor and ganglion cell layers, anatomically determined peak spatial resolving power, and the angular extent of the visual field. Peak densities of photoreceptors and ganglion cells occur in similar retinal locations. The topographic distribution of neurons in the ganglion cell layer does not differ substantially with eye growth. However, predicted peak spatial resolution increases with eye growth from 4.3 to 8.9 cycles/deg in C. plumbeus and from 5.7 to 7.2 cycles/deg in S. mitsukurii. The topographic distribution of different-sized ganglion cells is also mapped in C. plumbeus, and a population of large ganglion cells (soma area 120–350 μm2) form a narrow horizontal streak across the retinal meridian, while the spatial distribution of ordinary-sized ganglion cells (soma area 30–120 μm2) forms an area in the central retina. Species-specific retinal specializations highlight differences in visually mediated behaviors and foraging strategies between C. plumbeus and S. mitsukurii.

Review lecture: Apposition eyes of large diurnal insects as organs adapted to seeing

1980 ◽  
Vol 207 (1168) ◽  
pp. 287-309 ◽  
Keyword(s):  
Nodal Point ◽  
Visual Fields ◽  
Photoreceptor Cells ◽  
Resolving Power ◽  
Field Size ◽  
Correct Position ◽  
Anatomical Arrangement ◽  
Angular Coordinates ◽  
And Function ◽  
Facet Size

(1) The fields of view of the photoreceptor cells are determined by the dimensions and anatomical arrangement of the optical part of the ommatidium. The dimensions, and therefore the fields of view of the ommatidia are also related across the eye. In the relation between structure and function there are many points that invite discussion, but the intention is to order our knowledge so that the gaps become obvious. (2) The first step has been to make maps of the eyes showing the maximum theoretical resolving power of the facets and also the interommatidial angle, the reciprocal of which is the maximum spatial resolution of combinations of facets. The ratio of these two resolutions at each point shows the minimum overlap of the visual fields. These maps can be made from the outside of the eye; they show the main types of eye. (3) The next step is to work out the optics of individual ommatidia so that the focal lengths and receptor widths can be measured. The field width can then be predicted from the facet size and the subtense of the receptor at the posterior nodal point. The final step is to measure the field widths of individual ommatidia experimentally as a test of the optical theory, and to make maps of the actual fields in their correct position on the eye in angular coordinates. (4) Three examples of maps of actual fields are given, and their anato­mical and diffraction components are separated. The maps are an essential step towards the electrophysiological analysis of the ganglia behind the eye. A theory of the origin of the fields in terms of anatomy and optics also opens the way to an analysis of mechanisms that change the field size upon adaptation to light. A comparative study of the fields in different eye regions and in different species can also be related to visual habits and behaviour.

Recovery of function after lesions in the superior temporal sulcus in the monkey

1991 ◽  
Vol 66 (3) ◽  
pp. 651-673 ◽  
Author(s):  
D. S. Yamasaki ◽  
R. H. Wurtz
Keyword(s):  
Smooth Pursuit ◽  
Visual Motion ◽  
Visual Fields ◽  
Ibotenic Acid ◽  
Superior Temporal Sulcus ◽  
Position Error ◽  
Eye Position ◽  
Motion Information ◽  
Temporal Area ◽  
Rate Of Recovery

1. Ibotenic acid lesions in the monkey's middle temporal area (MT) and the medial superior temporal area (MST) in the superior temporal sulcus (STS) have previously been shown to produce a deficit in initiation of smooth-pursuit eye movements to moving visual targets. The deficits, however, recovery within a few days. In the present experiments we investigated the factors that influence that recovery. 2. We tested two aspects of the monkey's ability to use motion information to acquire moving targets. We used eye-position error as a measure of the monkey's ability to make accurate initial saccades to the moving target. We measured eye speed within the first 100 ms after the saccade to evaluate the monkey's initial smooth pursuit. 3. We determined that pursuit recovery was not dependent specifically on the use of neurotoxic lesions. Although the rate of recovery was slightly altered by replacing the usual neurotoxin (ibotenic acid) with another neurotoxin [alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)] or with an electrolytic lesion, pursuit recovery still occurred within a period of days to weeks. 4. There was a relationship between the size and location of the lesion and the recovery time. The time to recovery for eye-position error and initial eye speed increased with the fraction of MT removed. Whether the rate of recovery and size of lesions within regions on the anterior bank were related was unresolved. 5. We found that a large AMPA lesion within the STS that removed all of MT and nearly all of MST drastically altered the rate of recovery. Recovery was incomplete more than 7 mo after the lesion. Even with this lesion, however, the monkey's ability to use motion information for pursuit was not completely eliminated. 6. The large lesion also included parts of areas V1, V2, V3, and V4, but analysis of the visual fields associated with this lesion indicated that these areas probably did not have a substantial effect on recovery. 7. We tested whether visual motion experience of the monkey after a lesion was necessary for recovery by limiting the monkey's experience either by using a mask or by using 4-Hz stroboscopic illumination. In one monkey the eye-position error component of pursuit was prolonged to greater than 2 wk, but recovery of eye speed was not. Reduced motion experience had little effect on recovery in the other two monkeys. These results suggest that such visual motion experience is not necessary for the recovery of pursuit.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals A new genus and species of eomysticetid (Cetacea: Mysticeti) and a reinterpretation of ‘Mauicetus’ lophocephalus Marples, 1956: transitional baleen whales from the upper Oligocene of New Zealand

2018 ◽  
Author(s):  
Robert Boessenecker ◽  
R. Ewan Fordyce
Keyword(s):  
Phylogenetic Analysis ◽  
New Zealand ◽  
Temporomandibular Joint ◽  
New Genus ◽  
Feeding Strategy ◽  
Thoracic Vertebrae ◽  
New Genus And Species ◽  
Baleen Whales ◽  
Upper Oligocene ◽  
Lunge Feeding

The early evolution of toothless baleen whales (Chaeomysticeti) remains elusive despite a robust record of Eocene-Oligocene archaeocetes and toothed mysticetes. Eomysticetids, a group of archaic longirostrine and putatively toothless baleen whales fill in a crucial morphological gap between well-known toothed mysticetes and more crownward Neogene Mysticeti. A historically important but perplexing cetacean is “Mauicetus” lophocephalus (upper Oligocene South Island, New Zealand). The discovery of new skulls and skeletons of eomysticetids from the Oligocene Kokoamu Greensand and Otekaike Limestone permit a redescription and modern reinterpretation of “Mauicetus” lophocephalus, and indicating that this species may have retained adult teeth. A new genus and species, Tokarahia kauaeroa, is erected on the basis of a well-preserved subadult to adult skull with mandibles, tympanoperiotics, and cervical and thoracic vertebrae, ribs, sternum, and forelimbs from the Otekaike Limestone (>25.2 Ma). “Mauicetus” lophocephalus is relatively similar and recombined as Tokarahia lophocephalus. Phylogenetic analysis supports inclusion of Tokarahia within the Eomysticetidae alongside Eomysticetus, Micromysticetus, Yamatocetus, and Tohoraata, and strongly supports monophyly of Eomysticetidae. Tokarahia lacked extreme rostral kinesis of extant Mysticeti and primitively retained a delicate archaeocete-like posterior mandible and synovial temporomandibular joint, suggesting that Tokarahia was capable of at most, limited lunge feeding in contrast to extant Balaenopteridae, and utilized an alternative as-yet unspecified feeding strategy.

The variation of resolution and of ommatidial dimensions in the compound eyes of the fiddler crab Uca lactea annulipes (Ocypodidae, Brachyura, Decapoda)

1996 ◽  
Vol 199 (7) ◽  
pp. 1569-1577 ◽  
Author(s):  
J Zeil ◽  
M Al-Mutairi
Keyword(s):  
Visual Field ◽  
Fiddler Crab ◽  
Visual Fields ◽  
Horizontal Resolution ◽  
Resolving Power ◽  
Compound Eyes ◽  
Vertical Resolution ◽  
Histological Techniques ◽  
Uca Lactea

We studied variations in the optical properties of the compound eyes of Uca lactea annulipes using in vivo optical and histological techniques. The distribution of resolving power in the eyes of this fiddler crab species is typical for arthropods that inhabit flat environments: the eyes possess a panoramic equatorial acute zone for vertical resolution and a steep decrease of resolution away from the eye equator in the dorsal and ventral visual fields. The dimensions of the cellular components of the ommatidia vary accordingly: in the equatorial part of the eyes, facets are larger, and crystalline cones and rhabdoms are longer than in the dorsal and ventral parts of the eyes. Along the eye equator, horizontal resolution is low compared with vertical resolution and varies little throughout the visual field. The eyes of Uca lactea annulipes are unusual in that the gradient of vertical anatomical and optical resolution is steeper in the dorsal than in the ventral visual field. We interpret this difference as indicating that the information content of the world as seen by the crabs differs above and below the horizon line in specific and predictable ways.

scholarly journals The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina

2020 ◽  
pp. jeb.233098
Author(s):  
Fanny de Busserolles ◽  
Fabio Cortesi ◽  
Lily Fogg ◽  
Sara M. Stieb ◽  
Martin Luehrmann ◽  
...  
Keyword(s):  
Visual System ◽  
Reef Fish ◽  
Deep Sea ◽  
Colour Vision ◽  
Ganglion Cells ◽  
Light Sensitivity ◽  
Fish Family ◽  
Visual Systems ◽  
Retinal Topography ◽  
Dim Light

The visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual system of the nocturnal reef fish family Holocentridae. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim-light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae (squirrelfish) having a slightly more developed photopic visual system than Myripristinae (soldierfish). Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of the multibank retina and its potential for dim-light colour vision.

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