Brachyurans inhabit almost allaquatic habitats, ranging from mountain streams tothe abyssal ocean, with representatives interrestrial environmentsincluding those pro-viding only ephemeral or negligible water availability such as tree-holes (Cumberlidge &Vannini, 2004). Nevertheless, the majority of species are marine or estuarine. Truly fresh-water species that have done away with the need for marinelarval developmenthaveundergone a remarkableevolutionary radiationespecially through tropical regions, butaccount for<25% of the total. There are relatively few truly terrestrial species, which is tosay those not requiring regular immersion in water, e.g., members of the Grapsoidea andGecarcinidae, and genera such asGeograpsusandGeosesarma(Hartnoll, 1988; Ng et al.,2008; Yeo et al., 2008). Brachyurans demonstrate remarkable physiological, morphologi-cal, and behaviouraladaptationsto survive in diverse, including many extreme, environ-ments, e.g., long aestivation periods in desert-dwelling species, and physiological ability towithstand extremely high temperatures and toxic chemicals aroundhydrothermal vents(Greenaway & Macmillen, 1978; Martinez et al., 2001; Kicklighter et al., 2004; Comeault et al., 2010). Given their high level of abundance in some environments, crabs can there-fore play a significant role in the function of both terrestrial and aquaticecosystems, suchas directly or indirectly influencing the structure of the physicalhabitat(Warren & Un-derwood, 1986; Kristensen, 2008; Malyshev & Quijon, 2011), organic matter and nutrientflow (Bertness, 1985; Lee, 1998; Botto et al., 2005; Yeh & Drazen, 2011), andcommu-nity structure(Bertness et al., 2004; Hidalgo et al., 2007; Christofoletti et al., 2010). Theway in which brachyurans adapt to their physical habitat, and influence the structure andfunction of theirbiotic environment, is specifically explored in the following. ; Griffith Sciences, Griffith School of Environment ; No Full Text