Peru's rich biodiversity also includes organisms that live in the earth or soil fauna. These species are predominantly invertebrates, and have adapted according to the soil's composition, dampness and temperature. According to their size, these organisms can be categorised as microfauna (animals measuring less than 0.2 mm), mesofauna (measuring between 0.2 mm and 2 mm) and macrofauna (organisms larger than 2 mm).
Macrofauna includes more noticeable and visible organisms on the surface or in the soil, such as snails, earthworms, centipedes, millipedes, scorpions, ants, spiders and beetles, among others, and their observation and study attracts the presence of tourists and scientists with specific interests.
Invertebrates are the most common and abundant inhabitants of the soil, and play an important role in the process of decomposing organic matter. They break down vegetable and animal remains that make up the leaf litter, and facilitate the degrading activity of the soil microflora.