 Defences
Bugs are close to the bottom of the food chain. Almost everything eats
them—including humans! To survive this dangerous world of predators they
have evolved ingenious ways of defending themselves.
Active Defence
Many bugs are heavily armed and will fight back with a vengeance. Some insects
have sharp fangs, stings and claws. Others have armour that predators cannot
break through. The bombardier beetle mixes together a concoction of chemicals
in a chamber in its rear. When threatened, the beetle fires an explosion of
boiling liquid at its attacker.
Warning Colours
Many bugs are brightly coloured to advertise that they are poisonous. Red
colours or orange with black frequently indicate a bad-tasting meal. Predators
learn very quickly after an unpleasant experience that animals with these
colours should be avoided. The bugs make themselves poisonous or
bad-tasting by eating plants that have these properties, and then
concentrate the nasty chemicals in their bodies.
Mimicry
Some harmless bugs have evolved to look like dangerous bugs, mimicking the
colour patterns of venomous or poisonous bugs to fool predators. Predators that
have learned to avoid the genuinely dangerous bugs will also avoid their
mimics. There are insects that mimic biting ants, stinging scorpions, spiders
and even snakes. Barbed spines or other vicious-looking outgrowths on an
insect may be completely harmless.
Startling
Some bugs confuse their predators by flashing bright colours, large eyespots or
scary faces when attacked. Large eyespots on the wings of butterflies are used
to both startle predators and draw their attention away from the vital parts of
the body.
Camouflage
Many bugs are incredibly well camouflaged and are almost impossible to find when
they keep still. Some have bold irregular patterns that make it difficult to
see their body shape against backgrounds. Others have bodies that perfectly
resemble objects in their environment, such as leaves, sticks, thorns and even
bird droppings.
Spiny leaf insects have amazing camouflage. As their name suggests, adult spiny
leaf insects look exactly like dead leaves. They are almost impossible to see
amongst dry gum leaves. Their camouflage is so good that they even behave like
leaves and sway in the breeze.
|