| Challenger Deep |
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| pacific ocean | |
| oceania | |
| landforms of oceania | |
| extreme points of the world | |
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LOCATION It is in the Pacific Ocean , off the island of Guam in the Mariana Islands group at the southern end of the Mariana Trench . The closest piece of land is Fais Island , one of the outer islands of Yap , 289 km southwest. Guam is 306 km to the northwest. NAME The Challenger Deep is named after the Royal Navy survey ship '' Challenger II ,'' which surveyed the trench in 1951 . DEPTH On 23 January 1960 , the US Navy Bathyscaphe ''Trieste'' descended to the ocean floor in the trench. ''Trieste'', which was manned by Jacques Piccard and Lieutenant Don Walsh , measured the descent as 10,916 meters (35,813 feet) deep. The descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the 3 hour 15 minute ascent. They observed small Soles and Flounder s and noted the floor consisted of Diatom aceous ooze while on the bottom. In 1984 , a Japan ese survey vessel using a narrow, multi-beam Echo Sounder took a measurement of 10,923 meters (35,838 feet). A Japanese , 2003 , after just more than 8 years of service, when one of the secondary cables snapped during an approaching Typhoon . Currently no other operational vehicle exists that is capable of reaching the same depths, and no other manned vehicle has come to the same depth as ''Trieste''. FAUNA Recently, an analysis of the sediment samples collected by Kaiko before it sank, published in ''Science'', Vol 307, Issue 5710, pq. 689 {Link without Title} , announced the discovery of simple organisms at 10,900 meters water depth. While similar lifeforms have been known to exist in shallower ocean trenches (>7,000 m) and on the Abyssal Plain , the lifeforms discovered in the Challenger Deep possibly represent independent Taxa from those shallower ecosystems. Out of the 432 organisms collected, the overwhelming majority of the sample consisted of simple, soft-shelled Foraminifera , with four of the others representing species of the complex, multi-chambered genera ''Leptohalysis'' and ''Reophax''. Overall, 85% of the specimens consisted of organic soft-shelled allogromids. This is unusual compared to samples of sediment-dwelling organisms from other deep-sea environments, where the percentage of organic-walled foraminifera ranges from 5% to 20% of the total. As small organisms with hard calcated shells have trouble growing at extreme (10,000 m) depths because the water at that depth is severely lacking in Calcium Carbonate , scientists theorize that the preponderance of soft-shelled organisms at the Challenger Deep may have resulted from the typical Biosphere present when the Challenger Deep was shallower than it is now. Over the course of six to nine million years, as the Challenger Deep grew to its present depth, many of the species present in the sediment died out or were unable to adapt to the increasing water pressure and changing environment. The remaining species may have been the ancestors of the Challenger Deep's current denizens. EXTERNAL LINK |
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