A summer research expedition organized by scientists at
Scripps Institution of Oceanography at UC San Diego has led to the
identification of gigantic amoebas at one of the deepest locations on Earth.
During a July 2011 voyage to the Pacific Ocean's Mariana
Trench, the deepest region on the planet, Scripps researchers and National
Geographic engineers deployed untethered free-falling/ascending landers equipped
with digital video and lights to search the largely unexplored region. The team
documented the deepest known existence of xenophyophores, single-celled animals
exclusively found in deep-sea environments. Xenophyophores are noteworthy for
their size, with individual cells often exceeding 10 centimeters (4 inches),
their extreme abundance on the seafloor and their role as hosts for a variety of
organisms.
The researchers spotted the life forms at depths up to 10,641
meters (6.6 miles) within the Sirena Deep of the Mariana Trench. The previous
depth record for xenophyophores was approximately 7,500 meters (4.7 miles) in
the New Hebrides Trench, although sightings in the deepest portion of the
Mariana Trench have been reported. Scientists say xenophyophores are the largest
individual cells in existence. Recent studies indicate that by trapping
particles from the water, xenophyophores can concentrate high levels of lead,
uranium and mercury and are thus likely highly resistant to large doses of heavy
metals. They also are well suited to a life of darkness, low temperature and
high pressure in the deep sea.
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