"Cold Feet" - exploring Antarctica's extreme environments

Who would believe in penguins unless they had seen them? - Conor OBrien

I recently had the privilege of lecturing onboard the National Geographic Ship, Explorer, to Antarctica as an expert on extreme environments. Seeing the Antarctic landscape was beyond description. It is extraordinary to witness ice as far as the eye can see, and even more amazing to recognize that life thrives on this white landscape. This article about penguins is one of a series, in appreciation of this fragile continent.

Imagine living in cold water for food and recreation, but coming on land for breeding and raising children. Even worse, you live in a region where temperatures span one hundred degrees, from -60 C to 40 C. Few of us could tolerate trekking up to a hundred miles to find food for a child, or sometimes requiring several weeks to prepare dinner. How must it feel to be a bird with feathers, but sometimes act like a fish? What if you had devolved your wings, and instead evolved a flabby layer of blubber to assure your survival in cold water? And to top it off, your adaptations to this cold, icy habitat are now threatened by the fact that your polar world is melting at unprecedented rates. For your offspring, their food supply, nesting grounds and biological routine may face some rapid disruption and perhaps even threaten survival of your entire species.

This describes the lifestyle of a penguin. Amalgamated in the family, Spheniscidae, penguins are the only group of birds that have undergone dramatic adaptations to live in water as well as on land. Other bird families have become flightless species of cormorant, grebe, geese, swan, auk, and kiwi but no other birds can exploit the sea as elegantly as penguins. Although awkward on land, their spindle-shaped bodies lessen drag and energy expenditure when swimming. By trading flight for aquatic skills, penguins gain access to a vast oceanic smorgasbord of krill, squid and schooling fish such as sardines. And the penguins globular shape with its thick blubber minimizes heat loss in their polar environs. Penguins are built somewhat like a Thermos flask, with feathers locked together trapping a layer of air and providing insulation.

Penguins straddle two worlds land and sea. They live almost exclusively in the Southern Hemisphere. They are the only birds to breed in climates with an enormous temperature range. And to further differentiate these amazing bullets of blubber from other feathered cousins, different species of penguins have evolved to feed in different parts of the ocean: inshore versus offshore foragers. Approximately 16 19 species of penguins exist on Earth. How can there be confusion about the number of species? In the penguin world, there are several alleged subspecies, meaning their qualification as a full species is still not resolved. For example, the Royal Penguin is debated by some as a subspecies of the Macaroni Penguin. Currently, the small scientific community of penguin researchers classifies all 19 species, and continues to analyze any possible subspecies.

Swimming is more expensive and also slower than flying. As a result, penguins require a food source that is high in density to compensate for the energetic costs of reaching their dinner. Tropical waters would not suffice, because their water column is relatively low in productivity. In contrast, polar waters are incredibly rich in nutrition, with massive amounts of schooling fish such as krill and squid. Some penguins such as Gentoo penguins of Antarctica or Yellow-eyed penguins of New Zealand feed onshore, meaning they find food for their young within 50 kilometers of their nesting grounds. In contrast, Macaroni penguins forage far from shore, and sometimes require 15 days to forage distances up to 450 kilometers. The presence of sea ice can hinder the success of a feeding expedition; and scientists speculate that increased ice melt may significantly reduce a penguins ability to find food for its young.

Nature is full of trade-offs. For penguins, cold temperatures, icy waters, long treks to nesting sites, and melting icebergs represent advantages as well as challenges to their lifestyle. Fortunately, Mother Nature endowed them with a thick coat of blubber, incredible torpedo-shaped bodies for porpoising through cold waters, and an ability to fast for long periods while incubating an egg all unique traits that foster survival in extremes of Antarctica.

Having just traipsed amongst penguin colonies on a National Geographic/Lindblad expedition, I can also attest to the incredible odor of penguin nurseries. They defecate and vomit in their nesting sites, an odorous habit not readily explained by science. Perhaps the smelly slick enhances a penguins ability to body-surf across the snow? With scientists only recently beginning to scratch the ice about Antarctic ecology, many more facets of penguin lifestyles remain to be discovered. On a more sobering note, my ship colleagues informed me that some of the penguin colonies are greatly reduced in size over the past decade.

Penguins have something to teach all of us. How many creatures can survive subzero temperatures without shelter, without gloves, and in bare feet? How can small birds fast for weeks, and then dive 500 m undersea to eat raw squid, only to ascend rapidly without developing dangerous nitrogen bubbles in their blood? And what animals can incubate eggs and raise babies in windy, icy nurseries? Why, penguins of course!