How do terrestrial isopods and amphipods feed on leaf litter?

Terrestrial isopods and amphipods are malacostracan crustaceans that play a significant role in the breakdown of organic matter in forest ecosystems.12

These organisms consume forest leaf litter as a primary food source. Because fallen leaves are often initially too tough for many animals to digest, they typically undergo a process of decomposition by fungi and other microflora, which softens the leaf structure and makes it palatable. Once the litter is softened, these invertebrates fragment it into a mulch.23

While they do not significantly change the organic composition of the litter themselves, their feeding activity is essential because it creates a suitable substrate for primary decomposers—such as bacteria and fungi—to further break the material down into simpler chemical compounds. This process is part of a larger cycle where organic matter is digested and redigested by increasingly smaller organisms, eventually contributing to the formation of humus and the recycling of nutrients within the soil.3