From bacteria that can survive inside rocks to microbes that can
withstand tremendous heat, cold and radiation, life can take some
extreme forms. These enterprising creatures reveal not just the
resilience of life on Earth, but the possibilities for life elsewhere in
the universe. Here are some especially amazing examples of so-called
Not a drop to drink
Some organisms, such as <a href="http://www.ouramazingplanet.com/extreme-microbe-drinks-dew-on-spiderwebs-to-live-0550/"><em>Dunaliella </em>algae</a>
discovered in 2010 in a cave in Chile's Atacama desert, can thrive on
very little water. Despite living in the driest place on Earth, these
mooching microbes grow on top of spiderwebs to capitalize on dew – the
meager amounts of air moisture that condense on the webs in the
So-called hyperthermophiles are species that thrive in extremely hot environments. The <em>Aquifex</em>
genus of bacteria, for example, has been found living in hot springs in
Yellowstone National Park, where temperatures can reach 205 degrees
Fahrenheit (96 degrees Celsius).
One extreme species, the <em>Thermococcus</em> microbe, can survive on
so little energy that until now the chemical reaction it uses wasn't
thought able to sustain life. These organisms were found living near
deep-sea hydrothermal vents where super-hot water seeps out of the
Earth's crust near Papua New Guinea. In addition to their thrifty use of
energy, the microbes can survive in extreme temperatures too scorching
for most creatures.
Pass the salt
Talk about high sodium! Salt-tolerant "halophilic" microorganisms can
withstand salt concentrations that would wither most life. One example
is the bacteria <em>Halobacterium halobium</em>, which has evolved to live
in environments with 10 times more salt than seawater, such as the
salty lakebed of California's Owens Lake.
Brrr, it's cold in here
Some microbes, called psychrophiles, found in polar ice, glaciers and
deep ocean waters can withstand frigid temperatures as low as 5 degrees
Fahrenheit (minus 15 degrees Celsius). They consist mostly of bacteria,
fungi and algae, and contain enzymes that are adapted to function at
low temperatures. They have been found, for example, in the frozen
Arctic and Antarctic Oceans and beneath sheets of ice in Siberia.
Other extreme species prove their mettle by withstanding intense amounts of radiation. For example, the <em>Deinococcus radiodurans</em>
bacterium can survive a 15,000 gray dose of radiation, where 10 grays
would kill a human and it takes over 1,000 grays to kill a cockroach.
This species, in fact, is exemplary in many ways, encompassing also the
ability to survive cold, dehydration, vacuum and acid. The Guinness Book
of World Records lists <em>D. radiodurans</em> as the world's toughest bacterium.
Between a rock and a hard place
Endoliths are organisms that live inside rocks or other spots thought
impermeable to life, such as in crevices of animal shells or the pores
between grains of minerals. These species have been found over 2 miles
(3 km) below the Earth's surface, and may live even deeper. Water is
scarce at these depths, but some studies suggest they feed on
surrounding iron, potassium, or sulfur. While their choice of abode
presents some limitations, it also provides protection from harsh winds
and radiation from the sun.
This newfound creature, a loriciferan identified as an undescribed species of the genus Spinoloricus. The creature has specialized organelles so that it can survive without oxygen. Scale bar is 50 microns.