Amphibious Nature of Visual Acuity in the Asian “Clawless” Otter

Schusterman, Ronald J.; Barrett, Barry

doi:10.1038/244518a0

Cited by 24 publications

(15 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, amphibious vision is characteristic of otters and pinnipeds. Behavioral investigations have demonstrated good underwater visual acuity in the sea otter [Gentry and Peterson, 1967] and good amphibious visual acuity in the "clawless" otter [Schusterman and Barrett, 1973]. In agreement with the behavioral data, investigation of eye refraction has shown that a sea otter can focus objects both in air and water [Murphy et al, 1990].…”

Section: Coypu Myocastor Coypus Capybara Hydrochoerus Hydrochaeris supporting

confidence: 58%

Eye Optics in Semiaquatic Mammals for Aerial and Aquatic Vision

Mass

Supin

2018

Brain Behav Evol

View full text Add to dashboard Cite

Based on anatomical measurements of refractive structures in the eye, the positions of focused images were computed for several groups of semiaquatic mammals: rodents, a nonpinniped semiaquatic carnivore (the sea otter), and pinniped carnivores (seals, sea lions, and the walrus). In semiaquatic rodents, eye optics enable emmetropia in the air but cause substantial hypermetropia in the water. In semiaquatic carnivores, there are several mechanisms for amphibious vision that focus images on the retina in both air and water. These mechanisms include the potential for a substantial change in the lens shape of sea otters and the presence of the corneal emmetropic window in pinnipeds. The results suggest that several groups of mammals that independently adapted to aquatic environments vary in how their visual systems adapted to aquatic vision.

show abstract

Section: Coypu Myocastor Coypus Capybara Hydrochoerus Hydrochaeris supporting

confidence: 58%

Eye Optics in Semiaquatic Mammals for Aerial and Aquatic Vision

Mass

Supin

2018

Brain Behav Evol

View full text Add to dashboard Cite

show abstract

“…Amphibious animals that actively pursue fish underwater are assumed to retain a sharp image on the retina. However, neither the eyes of crocodiles (Fleishman et al, 1988) nor those of the amphibious snakes studied by Schaeffel and Mathis (1991) were well accommodated underwater, and, while clawless otters (A. cinerea cinerea) are emmetropic in both air and water, their acuity in either media is not high (Schusterman and Barrett, 1973). Thus, during underwater pursuits, animals may 'make do' with blurred images or make use of non-visual information.…”

Section: Discussionmentioning

confidence: 99%

“…To date, there are relatively few behavioral studies on visual acuity, the performance of visually guided tasks (Schusterman and Barrett, 1973) and the effects of the underwater light environment in amphibious animals and none, to the best of our knowledge, in pursuit-diving birds.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent studies have verified the extent of lenticular accommodation (e.g. Levy and Sivak, 1980; Schusterman and Barrett, 1973;Balliet and Schusterman, 1971) and sea lions (Zalophus californianus; Schusterman and Balliet, 1970) retain similar grating acuity in air and in water, crocodiles (including Gavialis, which feed exclusively on fish) do not accommodate underwater (Fleishman et al, 1988), implying that crocodiles can manage with blurred images.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Corneal power and underwater accommodation in great cormorants(Phalacrocorax carbo sinensis)

Katzir

Howland

2003

Journal of Experimental Biology

View full text Add to dashboard Cite

“…As for terrestrial mammals, it is reasonable to select species for comparative purposes which are taxonomically close to the sea otter. Behavioral measurements in some Mustelidae (Mustela putorius furo, Mustela erminea, Amblonyx cineria cineria) have shown slightly worse visual acuity than the sea otter: that is 13-16′ [Neumann and Schmidt, 1959;Balliet and Schusterman, 1971;Schusterman and Barrett, 1973].…”

Section: Retinal Resolution and Visual Acuity In The Sea Ottermentioning

confidence: 99%

Ganglion Cells Density and Retinal Resolution in the Sea Otter, <i>Enhydra lutris</i>

Mass

Supin

2000

Brain Behav Evol

View full text Add to dashboard Cite

The topographic distribution, density, and size of ganglion cells were studied in retinal wholemounts of the sea otter, Enhydra lutris. The cell distribution showed a well defined horizontal streak of higher cell density, and within this streak, a narrow area of the highest cell density. The peak cell density in this area ranged from 4050 to 4400 cells/mm², with a mean of 4225 cells/mm². The ganglion cell size ranged from 7 μm to 47 μm, but the majority of cells were 7 to 30 μm. Cell size distribution revealed three size groups: 7–16, 17–28, and 29–47 μm. The highest-density area contained mainly small (7–16 μm) cells. The cell-density data predict a retinal resolution around 7’ in water. Retinal organization in the sea otter exhibits more properties common with terrestrial rather than aquatic mammals, both in terms of ganglion cell characteristics and in terms of their topographic distribution.

show abstract

Amphibious Nature of Visual Acuity in the Asian “Clawless” Otter

Cited by 24 publications

References 5 publications

Eye Optics in Semiaquatic Mammals for Aerial and Aquatic Vision

Eye Optics in Semiaquatic Mammals for Aerial and Aquatic Vision

Corneal power and underwater accommodation in great cormorants(Phalacrocorax carbo sinensis)

Ganglion Cells Density and Retinal Resolution in the Sea Otter, <i>Enhydra lutris</i>

Contact Info

Product

Resources

About