Organism
Emperor Penguin
TL;DR
Stands on Antarctic ice at -40°F for 64 consecutive days during breeding season using countercurrent heat exchange.
Stands on Antarctic ice at -40°F for 64 consecutive days during breeding season using countercurrent heat exchange. Arteries carrying 95°F blood run parallel to veins carrying 35°F blood, transferring heat before reaching feet. Feet receive 35°F blood (just above freezing), core receives 85°F pre-warmed blood. Heat loss reduced from 100 watts to 10 watts, saving 2,000 calories/day and extending survival from 6 days to 64 days.