Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating.
Emperor penguin - Aptenodytes forsteri. This is the largest species of penguins. Emperor penguins are only found on and around the Antarctic continent, on the thick pack ice and rarely on mainland. They have a pale yellow, open (breast and chin patch are one) patch on chin and breast. A long, thin and curved bill, typical for fish eaters. Very dark grey back and blue black head.
It depends on the species because while the penguins of the Galapagos withstand a warm climate, the Adelie penguins (Pygoscelis adeliae) need low temperatures to avoid fainting; that is why, along with the emperor penguins, they are the only other species who live all their lives in Antarctica.