In 1989, I was lucky enough to visit the Antarctic for the first time, as part of the New Zealand Antarctic Research Programme. I was looking for nematodes, a group of worm-like invertebrate animals that live associated with the algae and moss that grow in the meltwater from snow and glaciers, and around the edges of lakes and small ponds. I visited various sites around the McMurdo Sound area of Antarctica, including the Dry Valleys which form the largest area of ice-free land on the continent. Parts of the Dry Valleys are called ‘oases’, because they support some visible signs of life. If you were expecting palm trees, however, you would be disappointed. Small patches of moss are as good as it gets in this part of Antarctica. The organisms that live here face some of the most extreme conditions experienced on Earth.

We all have ideas as to what might be normal and extreme environmental conditions. We might like our normal environment to be lying on the back lawn in the dappled sunlight with a gin and tonic. The heat of the desert (without the gin and tonic!) or the cold and wind of the Antarctic or Arctic might, in contrast, seem somewhat extreme. For other organisms (and even other humans), however, these places are home. In this book, I aim to explore the adaptations that have enabled organisms (including plants, animals and microbes) to live in situations that we might consider extreme and to try to develop a framework for thinking about organisms and extreme environments.