There is estimated to be around 200,000 breeding pairs of emperor penguins in the world, they reach breeding age at 4 years and can live to be 20. Emperor penguins breed almost exclusively on sea ice and so are perhaps the only species of bird that never sets foot on land.. and do not fly.
Very few people have seen an emperor penguin huddle in the winter in a savage place where ice and cold are king and the penguins spend days in silence. The only events are changing position in the huddle and the immense spectacle of the ghostly red, violet and green of the southern lights or Aurora australis playing in the dark skies above their heads
Early in the 20th century, Emperor penguins were thought to be some kind of evolutionary "missing link", something that scientists thought could be proven by observing the growth of the embryo at various stages.
A penguin's normal resting heart-beat is about 60-70 beats per minute (bpm), this goes up to 180-200 bpm before a dive as they load up with oxygen, then as they hit the water, the rate drops to 100 bpm immediately slowing to only 20 bpm during most of the dive so they use the stored oxygen in blood and muscles to the maximum effect. On returning to the surface again, the heart rate goes back to 200 bpm probably to pay back the "oxygen debt" they have incurred during the dive.