Most terrestrial invertebrates are restricted to the sub-Antarctic islands. Although there are very few species, those that do inhabit Antarctica have high population densities. In the more extreme areas of the mainland, such as the cold deserts, food webs are sometimes restricted to three nematode species, only one of which is a predator.[9] Many invertebrates on the subantarctic islands can live in subzero temperatures without freezing, whereas those on the mainland can survive being frozen.[10]