 It has been hypothesized that tunas can rapidly alter their whole-body thermal conductivity by at least two orders of magnitude.This is done by disengaging the heat exchangers to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are then reactivated to conserve heat when they return into the depths.Through this unique ability, tunas can reach out into otherwise hazardously cold water in order to hunt for food or escape from predators.