Millipedes and centipedes as soil animals

Abstract

The distribution of British millipedes and centipedes in relation to soil type and soil stratum is briefly reviewed. The presence of water in the soil, in creating problems of endosmotic uptake, oxygen lack and immobilization by surf ace tension, is considered an important factor determining this distribution. Geophilomorph centipedes have solved these problems by waterproofing their cuticle with a superficial film of lipoid; Iulid millipedes are similarly waterproofed but, unlike geophilomorphs, lay unprotected eggs; lithobiomorph centipedes and flat-backed millipedes have imperfectly waterproofed cuticles and are thereby restricted to positions from which water drains rapidly, for example under leaves and stones at the surface of the soil. Despite their hydrofuge cuticle most myriapods loose water rapidly through their spiracles - most rapidly in centipedes which have imperfect spiracular closing devices. Desiccation is avoided in geophilomorphs and Iulids by burrowing deep into the soil; lithobiomorphs and flat-backed millipedes are not mechanically adapted to burrow and thus their surface retreats must provide shelter from drought in addition to flood. The economic status of these animals in the woodland floor is discussed.