A Closer Look at Their Physical and Behavioral Adaptations
Photo by Paul Nicklen, National Geographic
•Approximately 40 species of penguins in the fossil record.
•Most likely penguins evolved from a small-sized ancestor that was capable
of flight.
•17 species of modern penguins worldwide—all residing in the Southern
Hemisphere*
•Highest diversity of penguin species found near the sub-Antarctic islands
•Antarctic penguins belong to three families—Aptenodytes “wingless diver”,
Pygoscelis “brush-tailed” and Eudyptes “true diver”.
•Early explorers mischaracterized penguins as fish due to their swimming
ability.
*Galápagos penguins take advantage of the cold-water Humboldt current that swings around the islands, thereby
allowing them to breed a few miles across the equator into the Northern Hemisphere.
Photo by: Doug Allen, Getty Images
•Hydrodynamic body “fat in the middle and tapered at both ends”
•Keel-shaped sternum and powerful pectoral muscles for
swimming and diving
•Head retracts slightly underwater to reduce drag
•Dense bones to help them dive
•Wings shortened, and wrist and elbow joints fused which creates
sturdy paddles for swimming.
•Legs shortened (knees and upper legs located up inside the body!)
and set-back, with paddle-shaped feet for steering underwater.
Photo by: Maria Stenzel, Nat. Geographic
•Emperor penguins are capable of some of the deepest and longest dives
of any penguin species. This is due in part to:
•Higher concentrations of the blood protein hemoglobin and the
muscle protein myoglobin allow penguins to store 2.5 times more oxygen
per unit of body mass than humans. (Norris 2007)
•Special properties of their hemoglobin helps it to bind with the last
remaining oxygen in their lungs.
•During dives—even when chasing after fish—their heart rate slows down
to 5 beats per minute. This reduces oxygen demand.
•Penguins also likely have reduced blood flow to their extremities during
dives.
Photo: Dave Houston, penguin.net.nz
•Beaks elongated for fish-dominant species like the Emperor.
•Beaks short and wide for the krill-dominant species like the Rockhopper.
•Beak and throat lined with angled spikes that point inward to grasp food
and keep it moving towards the stomach.
•Penguins have no external ears, which is an advantage in a very cold
climate (you don’t need to worry about your ears freezing off!)
•Ear holes are covered with feathers to keep water out.
•Penguins have an acute sense of hearing to locate mate and then
offspring in a crowded rookery.
•Penguins secrete excess salt from glands near their eyes. This allows
them to safely drink ocean water.
Photo by: Carlie Reum, NSF
•Feathers are shortened, stiffened and overlapping for waterproofing.
•Approximately 70 feathers per square inch
•Feathers coated with oil (preening) produced by a gland near the tail.
•Fluffy aftershaft near the base of each feather creates a downy layer of
insulation near the body.
•Penguins go through a complete molt every year—usually after the
breeding season—to replace worn out feathers. New feathers grow up
underneath the old ones.
•Coloration—dark from above and white from below—makes it more
difficult for predators and prey to see them. Dark feathers also absorb heat
from the Sun.
•Penguins usually have a one-inch layer of fat beneath the skin for
additional insulation.
Photo by: Caroline Gilbert 2006
•A penguins internal body temperature is between 100-102˚ F
•Penguins bring their flippers close to stay warm and raise them to
cool off.
•When incubating their eggs in the cold Antarctic winter, male
Emperor penguins will form a large huddle to stay warm. It gets so
warm on the inside of the huddle that the penguins rotate to the
outside to cool off.
•http://video.nationalgeographic.com/video/news/animalsnews/antarctica-emperor-penguins-huddle-vin/
Photos by: penguinscience.com
•Penguins fluff their feathers—thereby trapping more air—when
they want to stay warm. (photo above left)
•Penguins ruffle their feathers—to release the insulating layer of
air—when they need to cool down. (photo above right)
•Penguins preen—use their beak to groom their feathers—to keep
them in good shape. First they remove dirt and water, and then they
spread oil on their feathers to keep them waterproof.
•Sometimes penguins preen each other, called allopreening, which
increases social bonding.
Photo by: Alex Scott
•Penguins eat fish, squid and krill (a small shrimp-like crustacean).
Different species prefer different diets to avoid competition.
•Penguins “bulk up” their fat layer in preparation for breeding and
molting—two events during which they go long periods without
food.
•Most penguin species porpoise (see picture above) when at sea
looking for food in order to take a breath without slowing down.
•Penguins catch and eat prey while swimming.
Photo by: Daniel J Cox, Getty Images
• Some penguin species mate with the same partner for multiple
years. The likelihood of re-pairing decreases with increasing latitude
and decreasing length of breeding season. (In other words, no time
to hang out and wait for your prior mate to come back.)
•Adélies re-pair approximately 60% of the time, and they have a
very short breeding season since they are one of only two species to
breed on the continent.
•Gentoos, in contrast, re-pair 90% of the time because they have a
longer breeding season in the sub-Antarctic islands.
Photo by: Anne Owen
• In most penguin species, males and females take turns incubating
the egg and tending to the young so that the other parent can go to
sea to hunt.
•The returning parent regurgitates food into the mouth of the chick.
•Chicks join crèches (a large group of chicks, sometimes with an
adult “nanny”) around 3-6 weeks of age so that both parents can
hunt for food.
•The age at which different penguin species fledge (molt to adult
feathers and go to sea) depends on the time of year when their food
source is most abundant.
“At the place where they most often went in, a long terrace of ice
about six feet in height ran for some hundreds of yards along the
edge of the water, and here, just as on the sea-ice, crowds would
stand near the brink. When they had succeeded in pushing one of
their number over, all would crane their necks over the edge, and
when they saw the pioneer safe in the water, the rest followed.”
--George Murray Levick
Surviving member of Scott’s Terra Nova Expedition 1910-12
Describing Adélie penguins
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