 However, the assertion that these aspects of behavior and cognition do not exist outside amniota is largely based on absence of evidence (and hence, inherently limited). In particular, they do not offer direct support for their claims that non-amniotes are incapable of trading off punishments and rewards, play or detouring. Indeed, some of these claims appear to be contradicted by existing studies — for example, documentation of detouring in jumping spiders (Jackson and Wilcox 2003) and work by Elwood and Appel(2009) that shows motivational trade-off behavior in hermit crabs. 