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HOW A HARBOR SEAL SEES THE NIGHT SKY (2005)

Mauck, Björn ; Brown, Daniel ; Schlosser, Wolfhard ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Marine mammal science 21 (2005), S. 0

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ISSN: 1748-7692

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Astronavigation is a possible mechanism of offshore orientation in marine mammals. However, the basic prerequisite for astronavigation is to see enough stars of the night sky. This cannot be taken for granted in seals as, due to adaptations of their dioptric apparatus to the optical properties of water, seals are supposed to be myopic and astigmatic when out of the water under low light conditions. Using various real and artificial stars in a go/no-go response paradigm we therefore determined the minimum brightness at which a harbor seal (Phoca vitulina) can detect stars. The dark-adapted seal was trained to look through an empty tube (“seal telescope”) and to retract its head only when a star appeared at the opposite aperture. The seal reliably detected Venus or Sirius becoming suddenly visible when the telescope was moved across the night sky. Detection thresholds were determined using artificial stars (parallel light identical to starlight coming from the universe) of predefined brightness generated by an optical system installed in front of the seal's telescope. The seal detected artificial stars down to 4.4 stellar magnitudes. Although these results cannot present evidence for astronavigation, they imply that seals should see enough stars to allow such orientation mechanisms.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1748-7692.2005.tb01257.x

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Seal whiskers detect water movements (1998)

Dehnhardt, Guido ; Mauck, Björn ; Bleckmann, Horst

[s.l.] : Macmillan Magazines Ltd.

Nature 394 (1998), S. 235-236

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] How do pinnipeds orientate themselves under water? As most pinniped species feed in conditions under which visibility is drastically reduced, for example at night, at great depths or in murky waters, it has been particularly unclear how they succeed in finding food. Here we show that harbour ...