Literaturdatenbank
Literaturdatenbank |
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Dunson, W. A. (1986). Estuarine populations of the snapping turtle (chelydra) as a model for the evolution of marine adaptations in reptiles. Copeia, 1986, 741–756.
Added by: Admin (24 Aug 2008 18:46:23 UTC) Last edited by: Beate Pfau (28 Feb 2010 08:05:03 UTC) |
| Resource type: Journal Article BibTeX citation key: Dunson1986b View all bibliographic details  |
Categories: General Keywords: Chelydra, Chelydra serpentina, Chelydridae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Dunson Collection: Copeia |
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| Abstract |
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Chelydra serpentina In tidal creeks of the eastern shore of Virginia, the snapping turtle (Chelydra serpentina) is the primary freshwater turtle that intrudes into saline waters. Hatchlings derived from eggs of snapping turtles living in a saline creek grew significantly faster in 35% sea water, but slower in fresh water than those from a freshwater marsh. Hatchlings from the saline creek could not grow in salinities above 41% sea water (as compared to 64% for hatchling terrapins, Malaclemys terrapin). Subadult and adult snappers immersed in sea water for extended periods undergo a continual, gradual loss in body water and an increase in plasma osmotic pressure. There is no evidence for extracloacal excretion via a salt gland. Salt marsh populations of snapping turtles represent a very early stage in evolution for an estuarine life. Behavioral osmoregulation appears to be important, since adults move between the more and less saline portions of the creek, avoiding long-term exposure to potentially lethal salinities. The integument is quite permeable to water (about 280 μ mol/ cm2· h), but essentially impermeable to sodium. Body water efflux and net water loss in seawater are inversely proportional to body mass. Thus, larger turtles have a considerable advantage over smaller ones in attempting to osmoregulate in saline water. Added by: Admin Last edited by: Beate Pfau |