Ion Replacement as a Buoyancy Mechanism in a Pelagic Deep-Sea Crustacean
Ion Replacement as a Buoyancy Mechanism in a Pelagic Deep-Sea Crustacean
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离子置换作为远洋深海甲壳动物的浮力机制
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
J. Childress
中科院分区：
文献类型：
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作者：
N. Sanders;J. Childress
与大多数远洋甲壳类动物不同，深海虾驼背背口虾（A。Milne-Edwards）（Oplophoridae）是积极的浮力，拥有背侧扩大的甲壳，其中含有低密度流体。这种液体占动物湿重的43%，具有低pH值，并提供17.7 mg ml −1的升力;当这种液体被排出时，动物下沉。低密度是通过用离子替换浮力较小的离子来实现的，所述离子通过两种机制降低密度：通过使用较小质量的离子来改变总溶质质量，以及由具有大的正偏摩尔体积的离子引起的水分子结构的离子特异性破坏（导致流体体积增加）。大量的三甲胺（Me 3 NH +）是一种相对较大的重离子，它与NH 4 +一起置换了近90%的Na +，但对N的甲壳液中总溶质质量的影响很小。相对于海水（约34.1‰），驼背（33.2‰）。减少流体密度主要是一个结果的大，积极的部分摩尔体积的Me 3 NH +和NH 4 +，而不是减少溶质质量的函数。
Unlike most pelagic crustaceans, the deep-sea shrimp Notostomus gibbosus (A. Milne-Edwards) (Oplophoridae) is positively buoyant, possessing a dorsally enlarged carapace which contains a low-density fluid. This fluid comprises 43% of the animal9s wet mass, has a low pH, and gives a lift of 17.7 mg ml −1 ; when this fluid is drained, the animal sinks. Low density is achieved by the replacement of less buoyant ions with ions which reduce density via two mechanisms: a change in total solute mass by the use of ions of lesser mass, and an ion-specific disruption of the structure of water molecules (resulting in an increase in fluid volume) caused by ions having large, positive partial molal volumes. The presence of large amounts of trimethylamine (Me 3 NH + ), a relatively large, heavy ion which, together with NH 4 + , replaces nearly 90 % of the Na + in the carapace fluid, results in little change in the total solute mass of the carapace fluid of N. gibbosus (33.2‰) relative to sea water (approximately 34.1‰). Reduced fluid density is primarily a result of the large, positive partial molal volumes of Me 3 NH + and NH 4 + , rather than a function of reduced solute masses.