Basic mechanisms in pinniped vision

  title={Basic mechanisms in pinniped vision},
  author={Frederike D. Hanke and Wolf Hanke and Christine Scholtyssek and Guido Dehnhardt},
  journal={Experimental Brain Research},
Pinnipeds are amphibious mammals. The amphibious lifestyle is challenging for all sensory systems including vision, and specific adaptations of the eyes have evolved in response to the changed requirements concerning vision in two optically very different media, water and air. The present review summarizes the information available on pinniped eyes with an emphasis on harbour seal vision for which most information is available to date. Recent studies in this species have improved the… 
Eye Optics in Semiaquatic Mammals for Aerial and Aquatic Vision
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
Eye Histology and Ganglion Cell Topography of Northern Elephant Seals (Mirounga angustirostris)
Anatomical and histological traits of the eye that may improve light sensitivity in northern elephant seals are described, consistent with the predicted evolutionary adaptations to the photic environment of the bathypelagic zone.
Survey of ophthalmic disorders among captive pinnipeds in Japan
The results of this study indicate that ophthalmic disorders in pinnipeds are related to the conditions of their captive environment and Aquariums and zoos should be encouraged to share information regarding optimal maintenance practices to improve the living conditions of pinniped species.
Anatomy of the California sea lion globe.
The morphology of the California sea lion globe was analyzed to determine what features may contribute to their characteristic visual abilities, and the cornea and iris were examined.
Hydrodynamic perception in true seals (Phocidae) and eared seals (Otariidae)
The peculiar undulated shape of the harbour seals’ vibrissae appears to play a crucial role in trail following, as it suppresses self-generated noise while the animal is swimming.
Hydrodynamic Perception in Seals and Sea Lions
In the course of pinniped evolution at least two types of whiskers evolved that realized different mechanisms for the reception of external hydrodynamic information.
A Comparative Morphometric Analysis of Three Cranial Nerves in Two Phocids: The Hooded Seal (Cystophora cristata) and the Harbor Seal (Phoca vitulina)
The first comparative analysis of three CNs in two phocid seals is presented, finding pronounced differences in axon numbers/densities seem to reflect differences in e.g. size, habitat, and/or functional significance of the innervated sensory systems.
Contrast sensitivity in a harbor seal (Phoca vitulina)
The CSF of the Harbor seal shows the general characteristics described for other species with a peak at an intermediate frequency, a low frequency roll-off and a high frequency cut-off towards the harbor seal’s resolution limit determined in a previous study.
Comparative examination of pinniped craniofacial musculature and its role in aquatic feeding.
A comparative analysis of pinniped craniofacial musculature is conducted and suggests that pinnipeds' robust facial morphology allows animals to switch feeding strategies depending on the environmental context-a critical skill in a heterogeneous and rapidly changing underwater habitat.


The “sensitivity hypothesis” posits that the wide range of sensitivity observed in aquatic animals is a consequence of different species maximizing sensitivity to the broader range of light conditions available in various marine and freshwater environments.
Colour vision in aquatic mammals—facts and open questions
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.
Optokinetic nystagmus in harbor seals (Phoca vitulina)
Cone visual pigments of aquatic mammals
The hypothesis that in the monochromatic oceanic habitat, the pressure to maintain color vision has been relaxed and mutations are retained in the SWS genes, resulting in pseudogenes is supported.
Aerial visual acuity in harbor seals (Phoca vitulina) as a function of luminance
The results of this study support the hypothesis that harbor seals possess an aerial visual acuity comparable to the acuity in clear waters if the vertical slit pupil does not exceed the zone of corneal flattening in bright light.
Pinniped visual pigments.
  • D. Lavigne, K. Ronald
  • Biology
    Comparative biochemistry and physiology. B, Comparative biochemistry
  • 1975
For whales and seals the ocean is not blue: a visual pigment loss in marine mammals*
The S‐cone loss in marine species from two distant mammalian orders strongly argues for convergent evolution and an adaptive advantage of that trait in the marine visual environment, suggesting that the S‐cones may have been lost in all whales and seals.
The visual pigments of the bottlenose dolphin (Tursiops truncatus).
Although the dolphin possesses a gene homologous to other mammalian short-wavelength sensitive (SWS) opsins, it is not expressed in vivo and has accumulated a number of deletions, including a frame-shift mutation at nucleotide position 31, and therefore lacks the common dichromatic form of color vision typical of most terrestrial mammals.
Refraction of the Harp Seal, Pagophilus groenlandicus (Erxleben 1777)
THE dichotomy of the natural environment of amphibious mammals presents special optical problems if a well focused, faithful representation of their world in both media is to appear on the retina.