Page 197 - Atlas Of The World's Strangest Animals

BOTTLENOSE DOLPHIN 197

Dolphins are also one of the few species that are Dolphins are conscious breathers, which means that they
recognized as tool-users.A family of bottlenose dolphins have to remember to breathe, unlike humans who do it
from Australia’s Shark Bay famously use sponges to protect unconsciously.When they dive, they take a breath using an
their sensitive snouts when foraging for fish on the opening on top of their head, called a blowhole, to suck in
abrasive sea bed! air. Once underwater, they have to hold that breath or
they’ll drown.Thanks to millions of years of evolution,
Don’t forget to breathe! dolphins are efficient breathers and can exchange 80 per
There are two known species of bottlenose dolphin – the cent of the air in their lungs with each breath, compared
common and the Indo-Pacific (Tursiops aduncus). These to humans who can exchange only 17 per cent.This
charismatic cetaceans are air-breathing mammals whose allows them to stay submerged for up to 30 minutes at a
bodies have adapted to a completely aquatic life. time.When they sleep, another incredible adaptation kicks
in. It is believed that half of their brain sleeps at a time, so
that the other half remains alert to do the breathing!
Bottlenose dolphin habitats However, the dolphins’ oddest adaptation for an aquatic
life is echolocation. Echolocation enables them to hunt
even in the depths of the oceans where there is little light,
as well as to communicate with each other over vast
distances. Bats also use echolocation, and dolphins use
similar clicking sounds to build-up a 3D ‘picture’ of the
world around them.These clicks are passed through the
dolphins’ forehead (called the melon), which is filled with
fatty tissue and fluid.This acts like a lens, focusing sounds
in different directions.When these sounds hit an object,
echoes are received back through the dolphin’s lower jaw,
and this information is then passed to the brain for
processing. It’s an extremely efficient – if strange – method
of finding your way around.

Comparisons

Bottlenose dolphins’ powerful, streamlined bodies are ‘built’ for streamlined, with an elongated beak and a humped ridge
a life spent cruising through the world’s oceans. In contrast, along the back rather than the usual dorsal fin. River dolphins
Amazon River dolphins (Inia geoffrensis) thrive in silty, are also known as pink dolphins, although they’re frequently blue
slow-flowing water courses.Their bodies are therefore less or white.

Amazon river dolphin Bottlenose dolphin

(c) 2011 Marshall Cavendish. All Rights Reserved.