Asked by: Melanie O’Brien, London
The hands down hardest creature is a tardigrade, also known as a waterbear. Less than 1.5mm long, they can dehydrate their bodies to just 1 per cent of their normal water content.
Without water, most chemical reactions happen too slowly to harm them and ice crystals can’t rupture their cells. They are extremophiles – animals that can exist in the most hostile of conditions.
Tardigrades have been boiled at over 150ºC and frozen in liquid nitrogen without any noticeable harm. They can survive pressures of 6,000 atmospheres and in 2007, the Russian FOTON-M3 spacecraft took tardigrade passengers into orbit. After 12 days exposed to the vacuum, cold and radiation of space, they hadn’t just survived; they had laid eggs that hatched!