COMPARISON OF THE MUSCULOSKELETAL STRUCTURE OF THE ORBITS OF THE MIGRATING AND NONMIGRATING EYES IN THE WINTER FLOUNDER (PSEUDOPLEURONECTES-AMERICANUS)

  • 1 January 1987
    • journal article
    • research article
    • Vol. 47  (1) , 23-26
Abstract
The winter flounder, Pseudopleuronectes americanus, undergoes a metamorphosis that involves the migration of one eye across the top of the head to a position adjacent to the non-migrating eye on the right lateral side. The metamorphosis involves changes in the nervous and musculoskeletal components of the orbits. The major difference between the two eyes is that the orbit of the left eye is composed completely of bone, whereas that of the right is partially bounded by jaw muscles. The orbital bones of the left eye cause the path of the extraocular muscles and optic nerve to be deflected and twisted before insertion, causing the left lateral and medial rectus muscles to be significantly shorter than the same muscles of the right eye. These orbital asymmetries are necessary to accommodate the final position of the eyes in an extraorbital position on the right side, which is a specialized adaptation allowing the flounder to lead both a benthic and pelagic existence.