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Science Frontiers ONLINE No. 88: Jul-Aug 1993 |
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Whale falls: stepping stones across the ocean abysses
Unique biological communities flourish at widely separated "oases" on the deepsea floors, where hydrothermal vents supply the energy and chemicals necessary for life. Here are found free-living bacteria, tube worms, molluscs, and several other species that prosper without the benefit of photosynthesis. These chemosynthetic, thermal-vent communities are separated by thousands of kilometers of sea-floor "desert." Yet, the species involved are similar worldwide and must, at some time, have crossed these wide, forbidding expanses.
One possible mechanism for this mysterious dispersion came in 1987, when the research submersible Alvin chanced upon the remains of a 21-meter whale at a depth of 1,240 meters off California's coast. The whale's skeleton was covered with bacterial mats like those at the hydrothermal vents. Also sustained by the carcass were mussels, snails, and worms; all in all, a community much like those at the vents. Furthermore, many of the species partaking of the whale's energy and chemical resources are not normally found in that part of the Pacific. Subsequently, more "whale falls" with attached biological communities were found elsewhere. Calculations suggest that whale falls are more common that one might suppose -- perhaps occurring with average spacings of only 25 kilometers. They could very well be the stepping stones that allow hydrothermal vent communities to disperse across the abyssal deserts.
(Smith, Craig R.; "Whale Falls," Oceanus, 35:74, Fall 1992)