ESTUARINE POPULATIONS OF THE SNAPPING TURTLE (CHELYDRA) AS A MODEL FOR THE EVOLUTION OF MARINE ADAPTATIONS IN REPTILES
ESTUARINE POPULATIONS OF THE SNAPPING TURTLE (CHELYDRA) AS A MODEL FOR THE EVOLUTION OF MARINE ADAPTATIONS IN REPTILES
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DOI：
10.2307/1444958
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发表时间：
1986-08-04
期刊：
影响因子：
2.6
通讯作者：
DUNSON, WA
中科院分区：
文献类型：
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作者：
DUNSON, WA
在弗吉尼亚州东岸的潮汐小溪中，鳄龟（Chelydra serpentina）是入侵咸水的主要淡水龟。生活在咸水小溪中的鳄龟的卵在35%的海水中生长得快得多，但在淡水中比生活在淡水沼泽中的鳄龟生长得慢。盐碱河的幼龟不能在盐度高于41%的海水中生长（相比之下，孵化的水龟，Malaclemys terrapin为64%）。在海水中浸泡较长时间的亚成体和成体鲷鱼会经历持续的、逐渐的体内水分流失和血浆渗透压的增加。没有证据表明经盐腺排泄。盐沼的鳄龟种群代表了河口生物进化的早期阶段。行为渗透调节似乎很重要，因为成年人在小溪的高盐和低盐部分之间移动，避免长期暴露在可能致命的盐度中。被膜透水性很好（约280亩）。摩尔/ cm2 .cntdot。H)，但基本上不渗透钠。海水中人体水分流出量和净水分损失与体重成反比。因此，体型较大的海龟比体型较小的海龟在盐水中具有相当大的渗透调节优势。
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 .mu.mol/cm2 .cntdot. 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.