Micro-terraforming by Antarctic springtails (Hexapoda: Entognatha)

It has long been an axiom of Antarctic terrestrial ecology that interactions between terrestrial invertebrates and their abiotic environment are unidirectional: they are affected by their extreme environment in numerous ways, but they themselves do not affect their environment. Field observations in tandem with laboratory investigations of the exuvial refugia of the springtail Gomphiocephalus hodgsoni Carpenter, reported here, challenge this long-held assumption. These previously undescribed structures consist of minute lithic particulate matter that has been bound together by the accumulation of moult exuviae. Macrophotography, microscopy and manipulation assays demonstrated that the exuviae act as a kind of ‘cement’. Detachment of exuviae by emulsification indicated that this is mediated by the accumulation of cuticular hydrocarbons (retained in shed exuviae) at the lithic–exuvial interface. In addition to re-enforcing preferred microhabitat features by extending the hygrically buffered refuge phenotype, these structures contribute to primary soil formation processes through the structural cohesion of particulate matter. These by-products of moulting behaviour represent the first tangible evidence of environmental modification by terrestrial invertebrates on the Antarctic continent.