Adelie penguins are the smallest of the penguins living on the Antarctic continent.
Antarctica is home to an amazing range of wildlife that have developed some incredible adaptations in order to survive the harsh conditions they face.
21 August 2007 | Updated 14 October 2011
Antarctica is home to an amazing range of wildlife, considering the cold, dry and windy conditions that persist all year. The wildlife have developed some amazing adaptations to survive.
Penguins – dressed for survival
There are no mammals or birds that spend all year living on Antarctica. Penguins are the closest to permanent residents, and emperor penguins are the only animal on Earth that can survive temperatures as low as -50 °C.
Penguins are believed to have evolved from flying birds more than 40 million years ago. To live in the marine environment, they became more streamlined, developing waterproof feathers, short strong legs and webbed feet. Penguins walk upright because their legs are closer to their backs than their stomachs, which assists streamlining. Their flippers are wings that have become flat and broad, with the elbow joint and wrist nearly fused to make strong paddles.
To keep warm in the extreme cold, penguins have adapted in two ways; their physical appearance, and the way their bodies process energy.
Like all animals that live in very cold climates, penguins have large bodies and small appendages (feet, wings or flippers). By keeping feet and flippers close to the body, it is easier to keep warm. They have an amazing number of feathers (approximately ten per square centimetre), which are packed tightly together.
The physiology of a penguin has also adapted to the extreme cold. When it consumes food in winter, in converts most of the energy into keeping itself warm. However, when a penguin is a chick, it is kept warm by its parent’s body, and instead uses its energy to grow as fast as it can. As it grows older, it relies on its energy less for growing and more for warmth.
“I do not believe anybody on Earth has a worse time than an emperor penguin.”
Aspley Cherry-Garrard, Antarctic explorer
The colouration of penguins provides the perfect camouflage while they’re in the water. From above the water, predators find the penguins hard to see because they blend in with the dark depths of the ocean, and from below, predators see the penguin’s white stomach, which blends in with the surface of the sea and underside of icebergs.
Out of the water however, penguins are very conspicuous. Luckily for them, their only land predator is the leopard seal, which is deadly in the water but heavy and slow on the ice.
It is this lack of land predators that has made penguins the most successful animal species in Antarctica. There are around 24 million penguins in Antarctica and the sub Antarctic islands.
Seals – dogs of the sea
More than half of the world’s seals live in Antarctica. With no natural land predators, such as polar bears, Antarctic seals are unafraid of humans. This confidence made them vulnerable to hunting in the early 1800s. Therefore the sealing industry led a lot of the early exploration of Antarctica and the Southern Ocean.
Seals use sonar to navigate and find food, and use their whiskers as a kind of radar receiver.
Seals do not see colours in the same way we do. Their eyes have a silvery lining behind the retina, similar to cats and other nocturnal hunters. This lining reflects light not initially absorbed by the retina and increases the total amount of light absorbed, making it easier to hunt in the dark ocean. As such, they are particularly sensitive to colours found under water, such as green and blue.
When in the water, a seal's nose closes automatically and doesn't reopen until it resurfaces. An adult seal can stay underwater for 30 minutes before it must come up for air. In fact, seals sleep just under the surface of the ocean, resurfacing for air without waking up.
By Vanessa Woods
Find out more about Antarctica with Polar eyes.