Centre for Geobiology

Scientists have found organisms with many unique and novel characteristics living around hydrothermal vents.

The study of organisms living in the deep sea has forced scientists to expand the traditional definition of life. It is dark in the deep sea. The pressure is much higher than it is on land. The temperature is cold (away from the vents).  Food and energy are scarce.

Darkness is an important challenge. Traditionally it was believed that life on earth consisted of a food chain that was based on primary production, using photosynthesis to produce food and energy from sunlight. However, in the deep sea, the light from the sun does not extend more than about 200m deep. Life in the deep sea is dependent on the "left-overs" from the light-zone.

With the discovery of thriving ecosystems around hydrothermal vents (and some other specialised deep sea environments), researchers have learned that some organisms are able to derive the necessary energy for life from the earth itself. This alternative primary production process is called chemosynthesis.

We have all experienced changes in pressure underwater. A pressure of 1 atmosphere (atm) is defined at sea level. As one moves deeper in the water, the pressure rapidly increases. At just 600-700m deep the pressure is already between 60-70atm. Deep organisms have had to develop adaptations to this environmental constraint.

The temperature is low (away from the vents). It is uniformly around 4°C in the deep sea in all the world's oceans. However, the water steaming out of the vents can have a temperature be several hundred degrees. Microorganisms that live in hot environments are called thermophiles (meaning "heat loving"). Thermophiles thrive at temperatures of 50°C and higher. Hyperthermophiles thrive at temperatures up to 100°C.

In hydrothermal areas we find organisms that are able to transform compounds that are ‘toxic' for many other organisms into materials that can be used for food and energy. We also find representatives of another group of organisms that can live without oxygen, called ‘anaerobic' organisms.