Hydrothermal Vent Bacteria
Specialist Animals Survive High Temperatures around Black Smokers
Very hot water rushes up from the seabed carrying toxic chemicals, but animals are found there!
Volcanic activity causes Hydrothermal Vents (Black Smokers) in deep waters, with the dissolved minerals that are ejected condensing on contact with the cold water to form pipe-like chimneys. The water is heated to around 400°C and is rich in sulphides. The high temperature and chemical nature of this water would kill most animals, but many specialist species have been discovered.
Hydrothermal Vent Species
Many animals (including shrimps, crabs, giant tubeworms, clams, anemones, and fish) have been found close to the hot water, some of them able to tolerate temperatures approaching that of boiling water. Their food-chains owe nothing to sunshine and photosynthesis making their ecosystems unique. Specialist bacteria are able to harness energy from the chemicals in the hot water, and they feed the rest of the community either directly or through the food-chain. Because the volcanic activity is sporadic these communities of animals and bacteria cannot exist for long, so individuals must complete their life-cycles rapidly.
Giant Tubeworms
The Giant Tubeworm (Riftia pachyptila) is only found around Hydrothermal Vents and is the fastest-growing animal on earth - it can reach its full size (3 metres) in 18 months! It carries dense colonies of bacteria within its tissues, and these provide it with food in return for the sulphides they need. The worm has a lot of unusual haemoglobin which can carry sulphides instead of being poisoned by them, allowing the worm to collect nutrients for their symbiotic bacteria. This haemoglobin makes parts of the worm dark red.
Origin of Life
Many scientists speculate that places where volcanic activity releases a rich soup of chemicals into the sea might have been very important for the evolution of life on earth. Chemosynthetic organisms (rather like modern bacteria) might have first evolved around Hydrothermal Vents on the floor of the ancient oceans, with photosynthesis (what plants do) evolving much later. Life could have been dotted around the sea-bed long before it made it into the water or onto land.
Other Planets
There is certainly volcanic activity on other planets, and some of them also have water. If life did evolve (first or independently) around Hydrothermal Vents here on earth, then it raises the interesting possibility of discovering similar organisms on other planets eventually. If you remove the need for sunlight from the equation many planets could be considered, and when you take into account the temperature-tolerance of the bacteria around Hydrothermal Vents the number increases even more.
Primary Source: ‘Hydrothermal Vent Communities’ - Carolyn Scearce (PDF)
Other articles by John Blatchford
