Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating.
Emperor penguins owe their scientific name (Aptenodytes forsteri) to their discoverer, the first natural scientist to reach Antarctica, the German Johann Reinhold Forster. Forster came to Antarctica in 1770, on Captain James Cook's ship, and saved Cook's life during the voyage.
Aptenodytes forsteri, the Emperor penguin, is the largest of all species of penguins, with a height of up to 4 feet; and the Eudyptula minor, the little penguin, is currently the smallest with a maximum height of 1.25 feet.