Page 152 - World of Animals - Book of Sharks & Ocean Predators

Sharks & Ocean Predators
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3. They are able to
2. Penguins drink salt water

have 70 Another unique evolutionary feature possessed by
all penguin species is the ability to drink salt water
without any adverse side effects.

feathers per cannot drink ocean water due to its high salt
Humans and most other land-dwelling animals
square inch content, but penguins have evolved a special
supraorbital gland that filters all salt intake from its

bloodstream, enabling it to drink and be refreshed
as if drinking from a freshwater source.
As penguins spend so much of their
Warm coating The filtered salt, once extracted and separated

time in water, they need a reliable Feathers keep penguins from the animal’s bloodstream, is then eventually
waterproof coating, which for all species warm in freezing excreted as a concentrated fluid from the penguin’s

comes courtesy of their feathers. In fact, temperatures, but also
maintain a waterproof nasal passages.
these are some of the most dense and
barrier for swimming.
numerous plumages of all birds.
The average feather count per square BELOW Penguins are able to
inch (6.5 square centimetres) of a consume salt water, without
any adverse eff ects
penguin is 70 and with some species,
such as the emperor penguin, that
number rises to more than 100. These
small, stiff and tightly packed feathers
overlap and when in good condition
not only help insulate the bird against
its cold environment but ensure a
waterproof barrier is maintained at
all times, enabling the penguin to slip
through the water effortlessly before
returning to land in a fast-drying state.
On the rare occasion that a penguin
gets too hot, it cools itself by raising

its flippers, which are the one part of
its body, aside from the feet, where its
plumage is not so dense and heat can
escape quickly.
“The penguin varies its blood fl ow rate by
adjusting the diameter of its arterial vessels”

4. They can
Heat exchangers
A system of arteries
exchanges heat to control their
keep the extremities
as warm as
blood fl ow
possible.
Ever wondered why parts of a penguin don’t just freeze
Arterial vessels
The penguin is able and fall off in the harshest climate on Earth? Well, the
to adjust its blood answer is due to the ability to control its own blood

flow rate to suit the flow, which is certainly a handy trait when living in such

changing conditions.
typically cold climates.

The penguin varies its blood flow rate by adjusting
the diameter of its arterial vessels, supplying its blood in
accordance with climate conditions. In cold conditions
the diameter is reduced to limit the blood fl ow (which
reduces heat loss) and in warmer conditions the diameter
is expanded, increasing the fl ow.
Partnering this ability, which is controlled with a
complicated nervous and hormonal system, are also
countercurrent heat exchangers, which are positioned
at the top of the penguin’s legs and exchange heat from
warm blood travelling in one direction with cold blood
travelling in the other. This ensures that heat is distributed

efficiently around the body and that minimal loss occurs
at the extremities, while ensuring they don’t freeze.

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