Recent records of lithodid crabs in deeper waters off the Antarctic continental slope raised the question of the return of crabs to Antarctic waters, following their extinction in the lower Miocene ∼15 million years ago. Antarctic cooling may be responsible for the impoverishment of the marine high Antarctic decapod fauna, presently comprising only five benthic shrimp species. Effects of polar conditions on marine life, including lowered metabolic rates and short seasonal food availability, are discussed as main evolutionary driving forces shaping Antarctic diversity. In particular, planktotrophic larval stages should be vulnerable to the mismatch of prolonged development and short periods of food availability, selecting against complex life cycles. We hypothesize that larval lecithotrophy and cold tolerance, as recently observed in Subantarctic lithodids, represent, together with other adaptations in the adults, key features among the life-history adaptations of lithodids, potentially enabling them to conquer polar ecosystems. The return of benthic top predators to high Antarctic waters under conditions of climate change would considerably alter the benthic communities. © 2005 by the Ecological Society of America.