The reliance on a protective shelter is an important factor in the evolutionary history of hermit crabs, resulting in a distinct deviation from the typical decapod morphology. The abdomen is asymmetrical, soft and curled, adapted to coiling into the spiral of a gastropod shell. The telson is relatively small in hermit crabs and adapted to grasp onto the internal spiral of the host shell (Ingle and Christiansen 2004). Attempting to pull a hermit crab from its shell almost always results in the crab being torn in half (Ingle and Christiansen 2004), a testament to both its reliance upon its shelter and the strength to which its well adapted abdomen can hold on. The abdomen of all asymmetrical hermit crabs coils to the right and hence is better adapted to right-handed or dextril gastropod shells, though the less common left-handed shells are also utilised (Ruppert et al. 2004).