近日，日本科学家在世界上最深的马里亚纳海沟查林杰海渊附近发现一种靠从地幔物质中吸收营养的双壳贝，这有望成为探索地球上生命诞生之谜的线索。相关论文刊登在近期的美国《国家科学院院刊》（PNAS）网络版上。
日本海上保安厅日前说，其研究小组是在距查林杰海渊80公里处、约5620米深的海底发现这些贝类的。这次调查在2010年9月利用日本海洋研究开发机构的载人深潜器“深海6500号”实施。
这种双壳贝是一种白瓜贝，长12至13厘米，被认为是一个新品种。附近海底分布着地球内部地幔物质形成的岩石，白瓜贝就在岩石中喷出冷水的地点形成了大规模集群。
在这个地点，地幔物质形成的岩石与水发生反应而变质，白瓜贝以硫化氢为主要营养来源维持生命，这是世界上首次发现白瓜贝以这种方式生存。马里亚纳海沟的海底压力巨大而寒冷，曾被认为不适合生命，但近年来科学家已发现多种生物。研究小组认为，在马里纳亚海沟的其他地点和环境类似的汤加海沟，也有可能有同样的白瓜贝集群。
据推测，约40亿年前地球原始生命诞生的时候，也以起源于地幔的物质作为营养来源，所以此次发现将有助于探索地球生命诞生之谜。（生物谷Bioon.com）
doi:10.1073/pnas.1112005109
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A serpentinite-hosted ecosystem in the Southern Mariana Forearc
Ohara, Yasuhiko; Reagan, Mark K.; Fujikura, Katsunori; Watanabe, Hiromi; Michibayashi, Katsuyoshi; Ishii, Teruaki; Stern, Robert J.; Pujana, Ignacio; Martinez, Fernando; Girard, Guillaume; Ribeiro, Julia; Brounce, Maryjo; Komori, Naoaki; Kino, Masashi
Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures and vent communities occur in different tectonic settings. The discovery of the Lost City hydrothermal field in the Mid-Atlantic Ridge has stimulated interest in the role of serpentinization of peridotite in generating H2- and CH4-rich fluids and associated carbonate chimneys, as well as in the biological communities supported in highly reduced, alkaline environments. Abundant vesicomyid clam communities associated with a serpentinite-hosted hydrothermal vent system in the southern Mariana forearc were discovered during a DSV Shinkai 6500 dive in September 2010. We named this system the “Shinkai Seep Field (SSF).” The SSF appears to be a serpentinite-hosted ecosystem within a forearc (convergent margin) setting that is supported by fault-controlled fluid pathways connected to the decollement of the subducting slab. The discovery of the SSF supports the prediction that serpentinite-hosted vents may be widespread on the ocean floor. The discovery further indicates that these serpentinite-hosted low-temperature fluid vents can sustain high-biomass communities and has implications for the chemical budget of the oceans and the distribution of abyssal chemosynthetic life.
