On land, penguins use their tails and wings to maintain balance
for their upright stance.
All penguins have a white underside and a dark (mostly black)
upperside. This is for camouflage. A predator looking up from
below (such as an orca or a leopard seal) has difficulty distinguishing
between a white penguin belly and the reflective water surface.
Diving penguins reach 6 to 12 km/h, though there are reports
of velocities of 27 km/h (which are probably realistic in the
case of startled flight). The small penguins do not usually dive
deep; they catch their prey near the surface in dives that normally
last only one or two minutes. Larger penguins can dive deep in
case of need. The Emperor Penguin has been recorded reaching
a depth of 875 feet (270 metres) and staying submerged for 18
On land, penguins are clumsy. They either waddle on their feet
or slide on their bellies across the snow, a movement called "tobogganing",
which allows them to conserve energy and move relatively fast
at the same time.
Penguins have an excellent sense of hearing. Their eyes are
adapted for underwater vision, and are their primary means of
locating prey and avoiding predators; in air, conversely, they
are nearsighted. Their sense of smell has not been researched
Penguins have no external genitalia. Consequently, chromosome
testing must be done in order to determine a penguin's sex.
Sexuality and Mating Habits
Penguins mate for life. They generally raise a small brood, and
the parents co-operate in caring for the clutch and for the
Male penguin couples have also been documented. They too mate
for life and build nests together. Male couples have been recorded
using a stone to replace sitting on an egg in the nest. In
2004, the Central Park Zoo in the United States replaced one
male couple's stone with a fertile egg which they then raised
as their own offspring. This was the basis for the children's
picture book And Tango Makes Three. Homosexuality among penguins
has also been reported by a German zoo and Kelly Tarlton's
Aquarium in Auckland New Zealand.