Penguins are designed for life in the sea. Some species spend as much as 75% of their lives in the water. (They lay their eggs and to raise their chicks on land.) Heavy, solid bones act like a diver's weight belt, allowing them to stay underwater. Their wings, shaped like flippers, help them "fly" underwater at speeds up to 15 mph. A streamlined body, paddle-like feet, insulating blubber, and watertight feathers all add to their efficiency and comfort underwater. They also have a remarkable deep-diving ability.
In addition to blubber for insulating warmth, penguins have stiff, tightly packed feathers (up to 70 per sq. in.) that overlap to provide waterproofing. They coat their feathers with oil from a gland near the tail to increase impermeability. Black and white countershading makes them nearly invisible to predators from above and below.
Like most birds, penguins have little or no sense of smell (a boon for those in a crowded penguin rookery!) Like other birds, their sense of taste is also limited. Their vision appears to be better when they are underwater. Scientists suspect they may be nearsighted on land.
Penguins are considered to be the most social of birds. Rookeries may contain thousands of individuals. (As many as 24 million penguins visit the Antarctic continent!) Even at sea, they tend to swim and feed in groups.
Most species of penguins build nests, but the nests may consist only of a pile of rocks or scrapings or hollows in the dirt. Emperor penguins build no nests; they hold the egg on top of their feet under a loose fold of skin called the brood patch.
Make an animal suited for Antarctica.
- Brainstorm ways in which penguins are well-adapted to cold water and icy environments.
- Flying birds need a large wingspan to hold them in the air, but small wings work best for birds swimming through the water. Demonstrate this with two large sheets of paper. Try to push a sheet of paper through a pan of water. It doesn't push very well. Fold another large sheet of paper five or six times and try pushing that through the water. The smaller, stiffer paper, like a penguin's wing, works better.
- Most birds have hollow bones to make their bodies light enough to become air-borne. But the penguins' heavy, solid bones help them float lower in the water. You can demonstrate the difference between hollow bones and solid bones with two toilet paper rolls, one empty the other stuffed with tissue paper.
- Float an empty can in a bucket of water open end up. It floats high in the water like flying aquatic birds (ducks, for example). Add sand to another can until it sinks slightly. Now push down on both cans. The sand-filled container is easier to push down into the water. In this way, it is easier for a penguin to dive into the water.
- As a group, make a Venn diagram to show the ways that penguins are different from and similar to other birds.
- Have different groups of students make Venn diagrams showing how penguins are different from and similar to seals, whales, fish, and other birds.
- Using ideas from the discussion about penguin adaptations and Venn diagrams, have groups of students design a totally new marine animal that is also well-adapted for the cold.
- Make a picture of the animal.
- Model it from playdough or clay and place it in a shoe box diorama.
- Have students explain the rationale behind the design of their animals and habitats. Does it reflect earlier discussions?
- Use a globe to show that all 17 species of penguins live south of the equator. Penguins live along the western and southern coasts of South America, the tip of Africa, southern Australia, New Zealand, and all around Antarctica. One species, the Galapagos penguin, lives on the equator in the path of the cold Peru Current. Seven kinds of penguins visit Antarctica, but only two species, the Adelie and Emperor penguins, breed exclusively on the Antarctic continent.
- Penguins are the only birds that migrate by swimming. Trace the migration routes of these Magellanic penguins on a chart of the globe. They may migrate to the west coast of South America to Tetas Point in northern Chile or up the east coast of South America, past Argentina as far north as Rio de Janeiro in Brazil. Draw their routes on a map of South America and estimate the distance they have traveled.
Using satellite images, match their routes with the location of cold water currents.
- Research the route by which other species of penguins migrate. Use satellite images of the Southern Hemisphere and references on penquin migration to trace the migration routes of various species.
Discuss assumptions students can make about migration routes by looking at infrared imagery (penguins follow water currents).
The Great Auk
Research the Gulf of Maine's own "penguins," the flightless Great Auks. These birds became extinct in 1844 when two museum collectors landed on a remote island off Iceland and strangled the last surviving pair for their collection and then smashed the last egg.
Learn how Great Auks were similar to penguins. Find out why they were slaughtered (for food, their feathers, and for stuffed specimens for natural history collections).
Whaling and penguins
Whale and seal hunting were factors motivating the exploration of Antarctica. The whales come to Antarctica to feed in the summer (just as they return to the Gulf of Maine to feed). The decline in the whale population because of whaling means that fewer whales are eating the krill in Antarctica.
Discuss the potential impact of the removal of a major predator from the ecosystem. With fewer whales, more krill is left for the penguins. Scientists think the recent increase in penguin populations may be a result of an increase in krill available to the penguins. Could this theory be proved or disproved?
- Venn diagrams
- construction paper
- two empty toilet paper rolls
- two empty cans
- a bucket of water
- art supplies
- a shoe box for each student
- modeling clay or play dough