Creatures have adapted and survive in every habitat on earth. Dr Anjani Ganase looks at some of the strange organisms that thrive in extreme conditions.
Extremophiles are organisms that are adapted to living in the most inhospitable places on earth: in places of extreme cold or hot temperatures, under acidic or alkaline conditions, even in places under extreme pressure, buried under rocks or in the deep ocean. Such organisms have developed physical and behavioural traits that permit them to survive and to thrive in places that are devoid of other competing life.
[caption id="attachment_942693" align="alignnone" width="432"] Adult tardigrade. Photo by The Goldstein Lab -[/caption]
Desert rainbow fish is native to Australia and is a rare species of fish found in arid and semi-arid environments. They live in schools, grow to ten centimetres in length, and are iridescent in colour. They are adapted to living in small pockets of slow-moving water such as watering holes and ephemeral streams (bodies of water that remain for a short period after flooding), lakes and stock dams. These pockets of water in the Australian desert may only carry small populations of fish species but this does not prevent them from occurring in large numbers of watering holes throughout central Australia.
It is thought that the long-term survival of species in such isolated conditions may result in genetic die off in these small oases, but according to the researchers from Flinder’s University, they find a way. They can survive through drought conditions and are able to time breeding with the next flood event. The eggs are laid on the roots of vegetation or wetland plants or anything else in the water that they can adhere to. They hatch a week later. But flood events are unpredictable, and it is remarkable that they can survive such uncertainties. Adaptations include the ability to detect changes in water salinity, flow and turbidity. As climate change is resulting in more desertification, these creatures may even be able to expand their range.
[caption id="attachment_942692" align="alignnone" width="640"] Pompeii worm: Photo by The National Science Foundation -[/caption]
Cuddly water bears, known as tardigrades (literally means “slow stepper”) belong to a group of invertebrates made famous for their cute way of swimming through water. They are microscopic, growing up to one millimetre in length, and are found in almost all habitats on the planet yet we know so little about them. They can be found in temperatures as low as -200 C to over 150 C, in salty and fresh water, as well as under considerable pressures. They live in water and seem to survive in even the smallest water droplets. Tardigrades feed on biological matter including plant and animal materials, such as algae and amoebas. They are capable of surviving harsh conditions because of their ability to undergo cryptobiosis, a death-like state in which their metabolism is halted. They can do this in freezing conditions, changes in salinity, in the absence of oxygen and even
