The top large photograph is the head of a preserved squid, Sthenoteuthis oualaniensis. The white arrow points to the eyelid sinus. The insert photograph is an enlargement of the eyelid sinus from the first photograph. The eyelid sinus complex appears to enable complete closure of the eyelid. This is seen in the lower picture of a live squid, Ommastrephes bartramii, which is very closely related to Sthenoteuthis oualaniensis. The photographer had just touched the eyelid of this squid and it immediately responded by closing the eyelid. Note how the eyelid closed: The posterior edge of the eyelid expanded anteriorly providing most of the closure. The dorsal and ventral margins contracted and the flap over the eyelid sinus expanded to cover the remaining, slit-like opening. Probably a circular eyelid drawn together from all sides equally would not be able to close completely but would leave an central pore exposed.
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Figure. Side views of the heads of Sthenoteuthis oualaniensis (top) and Ommastremphes bartramii (bottom). Photographs modified from: Young, R. E., M. Vecchione and D. Donovan (1998).
Young, R. E., M. Vecchione and D. Donovan. 1998. The evolution of coleoid cephalopods and their present biodiversity and ecology. South African Jour. Mar. Sci.., 20: 393-420.
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University of Hawaii, Honolulu, HI, USA
National Museum of Natural History, Washington, D. C. , USA
Katharina M. Mangold (1922-2003)
Laboratoire Arago, Banyuls-Sur-Mer, France
Page copyright © 1997 , , and K. M. Mangold
Page: Tree of Life
Cephalopod Eyelid Sinus
Richard E. Young, Michael Vecchione, and Katharina M. Mangold (1922-2003).
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