6 - Habitats and Life

Summary

Here, I consider the wide variety of habitats in which organisms live. Some are obviously conducive to life, such as a rainforest, while others are not, for example a black smoker in a mid-ocean trench. Wherever the habitat of a particular organism is, it can be divided into microhabitats, each of which differs in its array of constituent species. I distinguish between the place where an organism lives and the way it makes its living there. The latter is often referred to as the ecological niche, though care is needed with this term as it is used in different ways by different authors. I then focus on three particular examples of habitats to get a more in-depth view: the soil, hydrothermal vents, and the intertidal zone. Finally, I ask the question: to what extent should we expect habitats on exoplanets to have similar features to those on Earth? Considering the ubiquity of topography (on rocky planets) and of liquid water (on habitable-zone rocky planets), it seems reasonable to expect both aquatic and land-based habitats; the latter will generally be a mixture of high and low altitudes, as well as high and low latitudes.