Penguins of Antarctica
In the frigid waters at the bottom of the world, one type of animal symbolizes the frozen landscape: the Spheniscidae family – aka. penguins! These flightless birds are specially adapted to survive in the bitter cold of the southern ocean, despite the harsh conditions that take over this region for the long austral winter.
How do they survive the cold?
There are three main adaptations that penguins have evolved in order to withstand the sub-freezing temperatures of Antarctica – feathers, fat, and size.
Although they cannot fly, their thickly developed wooly down feathers do an excellent job of insulating them against the powerful winds while on land, and are also streamlined to dry very quickly. The black color helps absorb the sun’s heat as well.
In the water, however, where these birds fish, it’s their thick layer of fat (up to 30 percent of their body weight) that protects them from the icy tides. And compared to the smaller penguins in the more northern latitudes, these birds are significantly bigger, which reduces the amount of heat lost per volume.
Other adaptations also contribute to a penguin’s ability to withstand the cold. Their feet and flippers, where they could lose a lot of heat, are controlled by tendons linked to muscles deeper in the insulated parts of their body, so there is never the risk that their muscles will freeze. Since they are warm-blooded, their bodies can also moderate blood flow to their feet and flippers so that when they are swimming circulation is lower and less heat is lost.
When standing on the ice or snow, they lean backward so that the only points of contact are their stiff tail feathers (which don’t lose any heat) and the heels of their feet.
In the case of rockhoppers, the rough ice-filled waters that crash violently against the rocky shores make it an everyday challenge to get from the water back onto land, as the tide washes powerfully over the slippery rocks, but their strong, gripping feet are a great asset.
While fishing, their agility is put to the test when confronted by hungry leopard seals hoping to snag their next meal.
On land, Emperor penguins demonstrate a unique social behavior to fight the cold – after returning from a fishing expedition up to a hundred miles from their colony, they must waddle back over the ice and snow and huddle for warmth. During the colder season, they live for extended periods of times (up to three months for the males) entirely on their fat reserves while incubating their eggs. They also rotate in shifts to the outside of the huddle to protect the group from the winds.
Of course, for a few months of the year, the bright sun blazes on the white Antarctic ice, raising the temperature significantly for these cold-water birds. While we might consider a southern summer pretty chilly, penguins rely on their ability to cool down, since their bodies naturally produce so much heat. Again, the ability to increase blood flow and lose heat quickly helps them with this.
There are seven main species that inhabit Antarctica and the surrounding islands:
- Adelie (Pygoscelis adeliae)
- Height: 70 cm (27.5 inches)
- Weight: 5 kg (11 lbs)
- Where to see them: Antarctica
- Population: 2.5 million breeding pairs
- Chinstrap (Pygoscelis antarctica)
- Height: 68 cm (27 inches)
- Weight: 4.5 kg (10 lbs)
- Where to see them: Sub-Antarctic, Antarctic Peninsula
- Population: 5 million breeding pairs
- Emperor (Aptenodytes forsteri)
- Height: 1.15 m (3.8 feet)
- Weight: 30 kg (66 lbs)
- Where to see them: Antarctica (southernmost penguin species)
- Population: 595,000 individuals
- Gentoo (Pygoscelis papua)
- Height: 71 cm (28 inches)
- Weight: 5.5 kg (12 lbs)
- Where to see them: Falkland & sub-Antarctic Islands
- Population: 320,000 breeding pairs
- Rockhopper (Eudyptes crestatus)
- Height: 55 cm (21.6 inches)
- Weight: 2.5 kg (5.5 lbs)
- Where to see them: Falkland & sub-Antarctic Islands
- Population: 1.8 million breeding pairs (in sharp decline)
- Macaroni (Eudyptes chrysolophus)
- Height: 68 cm (27 inches)
- Weight: 4.5 kg (10 lbs)
- Where to see them: Heard, South Georgia, & sub-Antarctic Islands
- Population: 9 million breeding pairs (in decline)
- King (Aptenodytes patagonica)
- Height: 95 cm (3.1 feet)
- Weight: 15 kg (33 lbs)
- Where to see them: South Georgia & sub-Antarctic Islands
- Population: 2- 3.2 million breeding pairs
Human Threats to Penguins
The remoteness of Antarctica buffers the continent's penguins from the impacts that many penguins in South America, Africa, and New Zealand, yet, according to the journal
Conservation Biology, there have been threats over the past approximately 250 years including harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species.
