The spectral sensitivity of a polar bear

Ronald, K.; Lee, J.

doi:10.1016/0300-9629(81)92582-2

Cited by 6 publications

(3 citation statements)

References 13 publications

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“…Hence, they can be considered welladapted to marine life. Polar bears are active under various illuminations from bright sunshine on snow to mid-winter darkness, but there is little information on their visual abilities and on the extent to which they depend on sight (for references, see Ronald & Lee, 1981). The visual environment of the pack ice zone is dominated by shades of white and grey and oVers hardly any opportunity for colour vision.…”

Section: Other Amphibious Mammalsmentioning

confidence: 99%

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Colour vision in aquatic mammals—facts and open questions

Griebel¹,

Peichl

2003

aquatic mammals

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Aquatic mammals had to adapt to visual environments that are very diVerent from those encountered by terrestrial mammals. Herein, we review the current knowledge on the colour-vision capabilities of aquatic mammals and discuss the puzzles that emerge from those studies. The common pattern in terrestrial mammals is dichromatic colour vision based on two spectral types of cone photoreceptors in the retina (commonly green and blue cones). Behavioural studies in a few pinnipeds and one dolphin species suggest a similar type of dichromatic colour vision in marine mammals. In contrast, recent immunocytochemical, physiological, and molecular genetic studies of the cone visual pigments in a larger sample of species show that whales and seals generally lack the blue cones and presumably are green cone monochromats. This challenges the behavioural ndings, because cone monochromacy usually is tantamount to colour blindness. Furthermore, a loss of the blue cones seems a rather inadequate adaptation to the bluedominated underwater light eld in the open ocean. Other aquatic and amphibious mammals (sirenians, otters, hippopotamuses and polar bear) appear to show the more common pattern of cone dichromacy. The present review summarizes available data on the various aquatic mammalian taxa, assesses the reliability of these data, and discusses the potential adaptive pressures involved in blue cone loss. It is suggested that blue cones were lost in an early, 'coastal' period of cetacean and pinniped evolution; many coastal waters preferentially absorb blue light and constitute a long-wavelengthdominated environment. Residual colour vision in these cone monochromats could be achieved in mesopic lighting conditions by exploiting the signal diVerences between the remaining green cones and the rods.

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Section: Other Amphibious Mammalsmentioning

confidence: 99%

“…Nevertheless, the only available study on polar bear spectral sensitivity, which is a behavioural one, reports a bimodal photopic curve with peaks at 525 nm and 450 nm, suggesting the presence of L-cones and S-cones (Ronald & Lee, 1981). The scotopic sensitivity peaks at 525 nm, suggesting a red-shifted rod pigment.…”

Section: Other Amphibious Mammalsmentioning

confidence: 99%

Colour vision in aquatic mammals—facts and open questions

Griebel¹,

Peichl

2003

aquatic mammals

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“…One explanation offered by Muntz is that a tungsten light background preferentially adapts the eye, and inhibits its response to longer wavelengths. Ronald and Lee (1981) offer the same explanation for a reverse Purkinje shift found in polar bears. The light adaptation level chosen for our measurements was similar to that encountered by cod of this size in normal daytime, and was one giving optimum brightness contrast sensitivity for this species (Anthony, 1981).…”

Section: Spectral Sensitivity Under Photopic Conditionsmentioning

confidence: 55%

Spectral sensitivity of the cod,Gadus morhuaL.

Anthony

Hawkins

1983

Marine Behaviour and Physiology

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The spectral sensitivity of the cod was determined under both dark adapted and light adapted conditions in the laboratory. Cod were trained by cardiac conditioning to detect a difference in radiance between an image of spots and the background radiance of a screen. Thresholds for this response were measured for a range of different wavelengths, and expressed as quantum adjusted values. Electroretinographic studies were also performed on the eyes of cod, and spectral sensitivity curves prepared. Under dark adapted conditions both the behavioural and e.r.g. derived curves showed greatest sensitivity in the blue/green at 490 nm, matching the absorption curve for rhodopsin. A secondary peak in the behaviourally derived curve in the green/yellow at 550 nm indicated that a population of yellow cones may be implicated with the rods in scotopic vision. Under light adapted conditions the behavioural curves showed a shift to the blue, perhaps indicating an adaption to the high red content of the illuminating source. The e.r.g. curve showed greatest sensitivity to blue/green, as in the scotopic experiments but with an enhanced response at 550 nm, indicating greater cone activity. It is suggested that there is complex interaction between rods and cones in the cod retina, both types of receptor being active over a wide range of light intensities.

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Polar Bear Behavior: Morphologic and Physiologic Adaptations

Whiteman

2021

Ethology and Behavioral Ecology of Sea Otters and Polar Bears

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The spectral sensitivity of a polar bear

Cited by 6 publications

References 13 publications

Colour vision in aquatic mammals—facts and open questions

Colour vision in aquatic mammals—facts and open questions

Spectral sensitivity of the cod,Gadus morhuaL.

Polar Bear Behavior: Morphologic and Physiologic Adaptations

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