It’s another ‘-phile’ word this week, but there’s nothing to worry about, honest. An extremophile is an organism that thrives in extreme environments previously thought to be uninhabitable, for example under massive pressure or really bastard cold. These organisms not only tolerate these conditions – for many, they need them to survive. Extremophiles have been found 6.7 km below the Earth’s surface, more than 10km deep in the ocean at pressures of up to 110 MPa (which is a lot, apparently), in acid, in frozen seawater at -20°C and in underwater hydrothermal vents at temperatures of 122°C. The name is made from the Latin extremus meaning, um, ‘extreme’, and the Greek philiā which means ‘love’.
A tardigrade*. Doesn’t he look like he’s about to start singing ‘Always look on the bright side of life’?
Extremophiles are also normally polyextremophiles (‘poly’ meaning ‘many’), which means they can live in more than one shit place – for example, the deep ocean is generally very cold and also under high pressure. So that’s a double whammy. And most extremophiles are microorganisms, but not all – the tardigrade (which I thought was a made-up thing in Star Trek) is one example. Also known as a water bear or moss piglet (awwww), a tardigrade is a microscopic eight-legged animal that thrives in environments that would kill most other forms of life – on mountaintops including the Himalayas, at the bottom of the sea, in mud volcanoes (which are literally what they sound like) and even in solid ice. They can go up to 30 years without food or water, and have been on earth for about 600 million years, which means they pre-date the dinosaurs by a mere 400 million years.
Not long ago, some nice scientists chucked a load of tardigrades out into outer space to see what would happen. Not only did lots of them survive, but some of them even went on to have babies. And in August 2019, scientists reported that some tardigrades might be living on the moon after an Israeli lunar lander carrying thousands of them crash landed (although it’s since been reported that they probably didn’t survive the impact, booooo). Both of these things sound like the start of really good sci-fi horror films.
The name ‘water bear’ comes from the way tardigrades walk, which apparently resembles the way bears get around. The largest ones can get to a (still pretty tiny) 1.5mm, which means you can see them using a bog-standard microscope if you have such a thing.
Extremophiles like the tardigrade are proof that life can exist in many different forms, and that oxygen and water aren’t pre-requisites. In the words of well-known mathematician and chaos theory specialist Dr Ian Malcolm (AKA Jeff Goldblum in Jurassic Park): ‘Life, uh, finds a way.’
*Wikipedia says I have to credit that tardigrade photo with this horrible bit of text: photo by Bob Goldstein and Vicky Madden, UNC Chapel Hill – http://tardigrades.bio.unc.edu/pictures/ >https://www.flickr.com/photos/waterbears/sets/72157607218607395/ >https://www.flickr.com/photos/waterbears/2851666759/in/album-72157607218607395 (note permission below), CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4747599).