Multifocal lenses in a monochromat: the harbour seal

Frederike D. Hanke, Ronald Kröger, Ursula Siebert, Guido Dehnhardt

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Previous photorefractive results from harbour seals indicated the presence of a multifocal lens. This was surprising because the evolution of multifocal lenses has served to compensate for chromatic aberration in animals with colour vision, which harbour seals as monochromats should not be capable of. To gain insight into the lens optics of these animals, we extended our photorefractive measurements in live seals under water and in air and, additionally, analyzed eight extracted juvenile harbour seal lenses with schlieren photography and a laser scanning technique. The results from all methods applied support the presence of multifocal lenses in harbour seals. However, the functional significance of multiple focal lengths in harbour seal lenses remains speculative. Interestingly, the slit pupils of harbour seals cannot be considered to be an adaptation to the multifocal optical system of the eye.
    Original languageEnglish
    Pages (from-to)3315-3322
    JournalJournal of Experimental Biology
    Volume211
    Issue number20
    DOIs
    Publication statusPublished - 2008

    Subject classification (UKÄ)

    • Zoology

    Free keywords

    • lens
    • harbour seal
    • Phoca vitulina
    • multifocal

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