Traditional groupings within the Anomura have been based largely on morphology. In addition to the Paguroidea (hermit crabs), extant anomurans are classified into six further superfamilies. The anomurans are considered the most morphologically diverse group within the decapods (McLaughlin 2010), but all can be described with one of the following body plans; crab-like, squat lobster, asymmetrical hermit crab and symmetrical hermit crab (Tsang et al. 2011). Which of these represents the ancestral Anomuran condition and how many times each generalised body plan arose has been the topic of considerable debate (Tsang et al. 2011)