Can anything live in hot, acid water? For years, people believed that there was no life in the steaming springs at Rotorua and other geothermal regions in New Zealand. But we now know that fascinating life forms survive there.
How much heat can life endure?
- The hottest temperature that humans, and most animals and plants, can live their whole life at is about 40°C – like a hot bath. (Hot water boils at 100°C.)
- Some insects can live at 50°C, and some plants at 60°C.
- Some bacteria can live at 70°C.
- Some bacteria live in even hotter springs, with temperatures above 80°C.
- The record-holder is Strain 121, an organism that grows at 121°C.
Extremophiles are tiny survivors. They live in extreme environments – hot, acid, salty or toxic. They were first discovered in hot springs at Yellowstone National Park (USA), in 1966. These organisms get their energy and nutrients from chemicals in the water.
- The heat-loving group are called thermophiles. They can live in water over 40°C.
- The acid-loving group are called acidophiles. They survive in some warm springs, with an acidity similar to car battery acid.
Life in the rocks
The rocky terraces and mounds around hot springs are made of a substance called sinter. Within its layers are tiny spikes and spheres – some are too small to see with a microscope. Here, micro-organisms make their home, sometimes colouring the rocks pink or yellow.
Studying hot springs
Scientists believe that life on earth evolved in a hot spring billions of years ago. Some researchers are investigating whether other planets have life forms like extremophiles. Scientists also want to find out if the organisms in rocks are actually building the layers of sinter, rather than just living on them. This could help us understand the origin of life.