All About Penguins

What’s in a Name?

The first time that the name penguin was given to a bird, it was the now extinct great auk of the North Atlantic. It was flightless and had a black back and white belly. So, when explorers later discovered similar birds in the southern hemisphere, they called them penguins too, not knowing they were unrelated. Hence, the first penguin wasn’t really a penguin at all, in the current sense of the word!

Although unrelated, the penguins of the south share many commonalities with the auks of the north (the great auk, puffins, murres, guillemots, and razorbills). They are countershaded with primarily black backs and white bellies. Their fusiform body type suits the watery world better than the air, and with their short powerful wings (or flippers), they “fly” while submerged.

Within the flipper, the bones are flatter and broader when compared to most other birds, and their elbows and wrists are almost fused to provide stiffness. The feathers on the wings are very short and more like scales. Their upright posture on land, which gives them their distinct hops and waddles, is due to how far back their webbed feet are situated on their bodies. In their predominately cold-water world, they are all exceptional fish hunters.

Penguin Preferences

When it comes to habitats, all penguins but one (the Galápagos penguin) live in the southern hemisphere. Their foraging range is more limited than flying birds, so they must find predictably available food within a smaller geographic area. These tend to be rich, cold ocean zones where there are upwellings and converging currents. Their flightlessness also makes it necessary to avoid areas where there are land predators, so they prefer remote islands or continental fringes.

Totally at home in the sea, they may spend months without coming to land. However, one thing they cannot do in the sea is lay an egg and raise a chick. For that they require terra firma, where they cluster in colonies, some of which are huge. They will also come ashore to molt.

Staying Warm and Cool

Despite their frigid environment, penguins maintain an internal temperature between thirty-seven and thirty-nine degrees Celsius. Dense, overlapping feathers create an impermeable barrier to water while downy tufts on the feather shafts help trap air, which is compressed during a dive and expanded again at the surface or on land.

A thick layer of subcutaneous fat helps preserve heat while also creating a streamlined body shape. Huddling together on land and turning their black backs to the sun also helps them stay warm.

In warm weather, penguins can become overheated, especially after a period of active swimming. They will then hold their flippers away from their bodies as the blood vessels dilate and blood flow increases to dissipate the heat. Overheated penguins can be recognized by the pink glow on their flippers and feet.

Besides serving as a rudder while swimming, their short, stiff tails allow emperor and king penguins to create a tripod with their heels, thus preserving heat by keeping the flat of their feet off the ground. They also use their feet to create a cup to keep their eggs off the ground.

Life at Sea

The water world of penguins is divided into strata, in which each species finds its favoured food. Some penguins, like the gentoo and emperor, hunt at the bottom, while other species stay higher in the water column. Most penguins stay in the upper waters and only submerge for a minute or so at a time. However, the longest recorded dive was by an emperor penguin for twenty-seven minutes, when it reached a depth of 565 metres.

With satellite radio tags, accurate swimming speeds have now been recorded for many species. They range from about two and a half up to an amazing thirty-six kilometres per hour in the case of the gentoo penguin. Some penguins leap through the air while swimming, a behaviour called porpoising. This may help penguins avoid swimming predators through momentary loss of visual contact, or it may help the penguins maintain momentum while breathing—or perhaps both.

Whereas flying birds have hollow, lightweight bones, penguins have solid, heavy bones that help reduce their buoyancy. Studies have shown that their heart rate slows during a dive compared to the resting rate at the surface.

Blood flow to peripheral parts of the body is restricted in favour serving the core organs. Other marine mammals show a similar adaptation. Penguins ingest a lot of saltwater, so they have glands above their eyes that help excrete the excess salt into a briny fluid that runs down and drops off their bill.

Conservation Status

Climate change is having a greater effect on the polar regions than on temperate areas, so the world of the penguin is changing. For example, the Antarctic Peninsula is warming five times faster than the average rate of the rest of the planet. It is six degrees Celsius warmer than it was sixty years ago and the ice season is ninety days shorter than what it once was. This reduces the availability of ice-dependent krill, a critical food of many penguins.

Bill Fraser, a researcher with the Palmer Long-Term Ecological Research program and president of Polar Oceans Research Group, has been studying the ecosystem of the northwestern Antarctic Peninsula since the 1970s. Since that time, the penguin population in this area has dropped by eighty-five per cent. Gentoo penguins, which favour slightly warmer conditions, are moving south and replacing Adélies. Fraser predicts that Adélie penguins will disappear from this area within the next few decades.

Ponder this: here is one of the hardiest creatures on earth unable to cope with the effects of human activities on continents oceans away.

It’s easy to smile as you watch penguins living their penguin lives: the cute bodies, the comic waddle, their swish through the water, the exchanges among adults and their chicks. But living in one of the world’s most inhospitable environments is a serious business, and they are superbly adapted to take it on.