Penguins are social birds that have adapted exceptionally well to life in water. There are between 17 and 20 living penguin species, and the largest living penguin species is the Emperor Penguin; adults average about 1.1 m (3 ft 7 in) tall and weigh around 35 kg (75 lb), the smallest penguin species is the Little Blue Penguin (sometimes called "Fairy Penguin"), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb).
Penguins usually live 15 to 20 years, depending on species. Penguins eat fish, krill and squid. They hunt their prey in water. They have no fear of humans because they do not consider us dangerous, and all in all penguins are really amazing animals.
The biggest problem for penguins are oil spills. Once oil gets on their feathers penguins are pretty much helpless to do anything about it. It is really difficult for penguins to avoid being coated by oil that floats on surface of the water. Penguins are often killed by empty tankers too. Tankers must fill their tanks with water and later this oily water gets discharged into ocean causing death to many unlucky penguins.
Global warming is not fully affecting penguins, at least not yet since temperatures have not yet crossed the danger zone but further temperature increase (which is very likely to happen) could be another harmful factor affecting penguin population.
There are 12 penguin species considered "at risk" or endangered, and mostly due to human activities. The most famous ones, the ones that live in Antarctica are thankfully not endangered, because they're fairly isolated from the rest of the world, but if global warming continues to strengthen its impact, isolation won't be enough to help them survive.
Of all the penguin species African penguins are mostly at risk of becoming extinct. Their population is experiencing continuous decline due to many different factors such as egg collection, increase of commercial fishing (less food for penguins) and of course above mentioned oil spills and tankers.
Although penguins have natural predators like leopard seals, sharks, orcas, sea lions, humans are the ones mostly responsible for so many deaths of these cute and so funny looking animals. And that's really not funny. Not funny at all.