Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

A Possible New Salt Gland in a Marine Homalopsid Snake (Cerberus rhynchops)

William A. Dunson and Margaret K. Dunson
Copeia
Vol. 1979, No. 4 (Nov. 28, 1979), pp. 661-672
DOI: 10.2307/1443875
Stable URL: http://www.jstor.org/stable/1443875
Page Count: 12
  • Read Online (Free)
  • Download ($12.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
A Possible New Salt Gland in a Marine Homalopsid Snake (Cerberus rhynchops)
Preview not available

Abstract

The dog-faced water snake, Cerberus rhynchops, apparently has a small premaxillary salt gland, which is not homologous with previously known lachrymal (turtles), nasal (lizards) or posterior sublingual (sea and file snakes) salt glands. Cerberus is a mangrove-dwelling snake that has adapted to a marine existence independently of the hydrophiids and the acrochordids. The premaxillary salt gland of Cerberus is small (approximately 0.005% body wt) and excretes sodium at about 15 μmoles/100 g body wt. h. When salt adapted, the glandular fine structure of the principal cells is very similar to that of other ophidian salt glands. However in fresh water striking changes in ultrastructure take place, indicating that the gland is probably readapting to serve a different function. The salt gland in Cerberus probably functions only during periods of dehydration, as the plasma Na concentration rises above 150 mM. The skin of Cerberus is virtually impermeable to Na, and overall Na influx (all oral) is extremely low, about 10 μmoles/100 g h. Almost all water exchange with sea water is through the skin, and net loss is relatively low. Cerberus can hydrate by drinking fresh water when it is available, and survive many months of sea water immersion before gradual dehydration causes the activation of the premaxillary salt gland. Even when fully active the gland can excrete only very limited amounts of electrolytes in comparison with some other marine reptiles. However the presence of even such a small source of extrarenal electrolyte excretion must be important to fasting snakes or those denied access to fresh or brackish drinking water for prolonged periods.

Page Thumbnails

  • Thumbnail: Page 
[661]
    [661]
  • Thumbnail: Page 
662
    662
  • Thumbnail: Page 
663
    663
  • Thumbnail: Page 
664
    664
  • Thumbnail: Page 
665
    665
  • Thumbnail: Page 
666
    666
  • Thumbnail: Page 
667
    667
  • Thumbnail: Page 
668
    668
  • Thumbnail: Page 
669
    669
  • Thumbnail: Page 
670
    670
  • Thumbnail: Page 
671
    671
  • Thumbnail: Page 
672
    672