The feature that makes animals so different from other living things
is their ability to move. Some do not move much – a sea anemone,
for example, is sedentary (remains in one place) and catches
anything that touches its tentacles. Most animals, however, travel
to look for food, find breeding partners, or escape from their
enemies. They slither, crawl, walk, hop, run, swim, and fly,
sometimes at incredible speed. Some have evolved
other amazing ways of getting about, like the
insects and spiders that walk on water, and
the extraordinary sidewinding rattlesnakes.Movement
50
(^1) GIBBON
Although gibbons can walk
well, they usually move through
the forest by using their long,
powerful arms to swing from the
trees. They hurl themselves from
branch to branch with astonishing
speed, agility, and elegance.
(^3) OCTOPUS
An octopus normally hauls itself
over the seabed using its long,
elastic arms. But it can shoot away
from danger by jet propulsion,
drawing water into its body and
blasting it out at high pressure.
Cuttlefish and squid do the same.
(^2) SNAKE
A typical snake slips along by
curving its flexible body around
plants and stones, and pushing the
curves towards its tail. Sidewinders
like this desert viper have a more
baffling method, looping sideways
over the sand like rolling springs.
(^4) PENGUIN
All penguins are superb swimmers,
using their wings to “fly” through
the water, but they walk clumsily.
On snowy slopes they often prefer
to toboggan on their well-padded
bellies, pushing themselves along
with their stoutly clawed feet.
(^5) FISH
Most fish have flexible bodies
that allow them to move through
the water using their fins for
stability and to control their
direction. Some fish, such as
tunas, propel themselves at
high speed using just their tails.
(^6) STARFISH
A starfish can curl its arms, but
it actually creeps over the seabed
using hundreds of tiny “tube feet”
on its underside. Each tube foot
is pumped full of water, and
is extended and moved by
changes in water pressure.
(^7) SNAIL
The muscles in a snail’s foot
contract and expand to create
a rippling movement that pushes
the snail forward. Glands in the
foot produce a slimy mucus to
make the track slippery. The slime
also protects the snail from debris.
1
2
3
7
8
050_051_Movement.indd 50 03/01/19 12:09 PM