From the deep:

• Ceratiida angler fishes have acquired bizarre adaptations; males become tiny parasitic attachments on females enabling mates to stay together once encountered in the dark abyss.
  
  
• Icefishes (Notothenioidei) in Antarctic oxygen-rich waters have overcome the challenges of increasing blood viscosity and strain on the heart and circulatory system by foregoing red blood cells and by evolving large hearts and highly vascularised skin in contact with the water.

< Viperfish, Mid-Atlantic ridge. Photograph by David Shale, courtesy University of Aberdeen. http://news.nationalgeographic.com/

At high altitudes:

• At extreme elevations (over 4000 m above sea level), UV radiation can cause severe damage; the surviving organisms and these environments provide natural laboratories simulating conditions such as those during the early development of the Earth's atmosphere and life on Mars.
  
  
• Low oxygen conditions at high altitude may have resulted in convergent but distinct solutions in low-oxygen abyssal oceanic depths or those found deep within cave systems of the Earth; comparative studies of species with high metabolic demands in these anoxic environments will help reveal why some were able to colonise these habitats and how.
  

< Vicuñas, Laguna Pozuelos, Argentina, 3700 m. Photo: G. Ibarguchi

Life in the cold:

• Cold regions around the world such as the Arctic, Antarctica, and high altitude environments, may be remote, but show evidence of pollution from sources evaporating from warmer regions and condensing at cold temperatures, such as DDT.
  
  
• During the short Arctic summer, hundreds of thousands of waterfowl, seabirds and shorebirds migrate north to breed; many shorebirds including representatives from Calidris, Numenius, Pluvialis, and Tringa, have essentially bipolar distributions, wintering in the Southern Hemisphere and breeding in the Arctic.
  
• Cold hardy terrestrial and marine species have evolved specialised morphology and biomolecules to cope with their environments (e.g. hemoglobins, cryoprotectants, and adaptations in their metabolism).

< Avalanche, Southern Andes, Chile. Photo: G. Ibarguchi

Polar habitats:

• The cooling of Antarctica during the last 30 million years resulted in the extinction of most of its terrestrial fauna and flora, and much of the marine biodiversity. However, recent genetic evidence is revealing that many lineages survived as relicts on the frozen continent to the present, and many others only 'recently' dispersed or were transported out, and formed new sister species with disjunct distributions around the world.
  
  
• Despite the molecular complexity of cryoprotectants such as antifreeze proteins, fishes in the Arctic and Antarctica have evolved equivalent forms, from independent origins, but as convergent solutions to similar environmental conditions.
  
• Aside from cold, polar species are adapted to extended darkness during long winters lasting months, high UV radiation lasting months, short growing seasons, drought, exposure, and high winds.

< Canadian Arctic in June. Photo: G. Ibarguchi

Dry environments:

• Some polar regions are extremely dry, not only due to low temperatures, but also due to the presence of polar deserts. In Antarctica, the Dry Valleys are among the driest places on Earth.
  
  
• Rain has never been recorded in some areas within he Atacama Desert in Chile, a severe environment almost devoid of vegetation where night temperatures can plummet below -10 °C while high summer temperatures return during the daytime at some elevations.
  
  
• Far apart, ecologically the Dry Valleys and the Atacama Desert may not be so different after all. Simple communities such as hypoliths thrive under translucent rocks where water exists briefly through condensation, and where shelter is provided from the intense radiation and wind.

< Top: Atacama Desert, Chile. Photo: G. Ibarguchi

< Bottom: Dry Valleys, Antarctica. Photo: R. Ropper-Gee
http://www.mcmurdodryvalleys.aq/photos/category/6-stations-camps-and-logistics

Chemical gradients and geothermal habitats:

• Despite the toxic presence of sulphur, heavy metals, and other compounds, volcanic and geothermal sources provide niches for extremophiles able to utilize alternate sources of energy (chemoautotrophs). Many remarkable extremphiles can simultaneously tolerate extremes in pH and salts, such as some Dothideomycetidae fungi.
  
  
• Species inhabiting deep sea vents, fumaroles, and geothermally-heated environments can often withstand extreme heat and wide temperature fluctuations. Studying how these organisms and their enzymes survive high temperatures (some well above the boiling point of water), as well as their symbiotic relationships to metabolise and thrive despite their toxic environment, may provide valuable knowledge in fields from astrobiology to medicine and environmental remediation.

< Sulphur flats, Río Putana, Chile. Photo: G. Ibarguchi

Caves:

• Caves can serve as sheltered habitat in harsh environments. However, conditions can become inhospitable deep within caves. Oxygen and gas exchange may be severely reduced, darkness may be complete, and temperature may be cooler near the surface or hotter if nearby geothermal energy reaches deeper chambers.
  
  
• Chemoautotrophs can support communities within caves where photosynthesis ceases. Caves may serve both as regions of diversification of specialised cave-dwelling lineages and as refuges where ancient lineages can be found.

< Caves in islands in the Caribbean. Photo: G. Ibarguchi

Astrobiology:

• Studies of life in extra-terrestrial environments, Early Earth studies, and research related to designing optimal equipment for exploring space have been conducted in harsh analogous conditions on earth.
  
  
• High altitude environments provide conditions of elevated UV radiation; Antarctica mimics exposure to extreme cold; hot and polar deserts reveal how life survives with limited moisture; volvanic regions provide insight into energy conversion mechanisms and how communities can be supported by chemoautotrophs.
  
  
• Remote pristine regions are often chosen for monitoring and obtaining baselines as these regions may provide reduced pollution from human activities such as light and noise, and toxic contaminants. However, long-distance transport of pollutants into remote regions is on the rise. Human activities in remote regions can greatly impact fragile lifeforms in these harsh ecosystems, which despite their sterile apprearance, harbour highly specialised communities.

< G8 Hokkaido Toyako Summit 2008, Poster, Japan. Modified photo: G. Ibarguchi

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