|A caterpillar’s bristles, like those of this gypsy moth
caterpillar, can be
used as a defense against predators.
Spikes And Spines
Most insects have thick outer skeletons that serve as armor.
These exoskeletons may also boast spikes and spines, which add
to an insect’s defense. Many species of crickets and grasshoppers,
for example, have spines on their legs and backs. Many ants have
spines in the middle of their back that protect them from other
insects’ nipping jaws. Praying mantises have spurs on their claws
that not only help in grabbing prey, but also inflict wounds on
Caterpillars typically have soft bodies. This makes them
tempting morsels for predators. But most caterpillars have other
ways to protect themselves. Some have spikes or spiny, hair-like bristles. Caterpillars can be so bristly that they appear to have
fur. The bristles irritate a predator’s skin and eyes. If a predator
accidentally inhales some bristles, they can hurt its nose, throat,
Other small animals have spines, spikes, and bristles, too.
The spined spider has an array of big, red spines on its body. Millipedes
have bundles of barbed bristles along their bodies and on
their hind ends. These bristles come off and get stuck in the faces
and jaws of ants and other predators.
Large spiders called tarantulas also defend themselves with
bristles. A tarantula uses two of its hind legs to rub bristles off its
abdomen, which sends hundreds of the tiny barbed bristles at the
attacker. The bristles irritate its eyes, nose, and mouth.
|Sea urchins, like this common sea urchin found
along the coast of Scotland,
use their bristles for
moving as well as defense.
Spikes and spines also protect animals that live underwater.
The tiny young, or larvae, of crabs have spines that help
them float while also repelling fish. Likewise, spiny lobsters are
protected by spines that line their antennae and point forward
along their shells. The crown-of-thorns sea star is also spiny.
This sea star has as many as 19 arms, with sturdy pink or yellow
spines poking out of its orange, red, and purple skin. The
spines not only pierce skin, but also deliver a dose of painful venom.
Sea urchins are like living pincushions. Their hard, round
bodies bristle with spines. An urchin uses its spines to help it
move. The sharp spines also keep many predators at bay. Some
sea urchins’ spines are connected to glands that make venom.
Long-spined hatpin urchins have venomous spines that can be
up to 12 inches (30 cm) long. Some species of fish and jellyfish
hide in hatpin urchins.
Stonefish have spines connected to venom glands, too. These
are well-camouflaged fish that lie on the seabed in some tropical
waters. Their spines pierce and kill predators that grab them.
Surgeonfish, which also live in tropical waters, have a pair of razor-like spines on either side of the tail. The fish slashes at attackers
with these spines.
Sticklebacks are named for the spines that stick up on their
backs. A stickleback can lock these spines in an upright position.
The number of spines varies, as shown by their names, which
range from three- to fifteen-spined stickleback.
The porcupine fish’s name is likewise a clue to its defense.
This fish is covered with sharp spines. When threatened, the
fish inflates its body with water, and the spines stick out in all
directions. This makes the fish too big for some predators to swallow. It startles other predators, which may decide not to
tackle the suddenly enlarged prey.
A variety of lizards also wear spike-studded armor. The
well-named thorny devil resembles a miniature dragon as it
strolls across the Australian sand, looking for ants to eat. Spikes
of many sizes jut from its legs, sides, tail, back, and head. Despite
its name, a thorny lizard is not aggressive. If threatened, it
tucks its head between its front legs. This makes a large, spiky
bump on its neck stick out—a bump that looks like an even
more unappetizing head than the lizard’s actual one.
|This thorny devil shows off its spikes of many sizes as it
walks along a
street in the Northern Territory, Australia.
Just as prickly are the horned lizards of dry lands and deserts
in parts of Mexico and the southwestern United States. A horned lizard has spines running down its sides, back, and tail.
Strong, sharp horns jut from its head, making it look like a tiny
triceratops. If a predator threatens it, a horned lizard puffs up its
body so that its spines stick out. It also turns its head to present
its horns. Some species can also squirt blood from the corners of
their eyes. The blood can shoot out up to 3 feet (1 m). The blood
tastes bad, so the squirt both surprises and disgusts a predator.
The armadillo lizard of southern Africa is also spiky. It
makes the most of its spikes by rolling into a ball and grabbing
its tail in its mouth when threatened. This turns the lizard into
a prickly doughnut.
Mammals also make use of spines for protection. Porcupines,
for example, fend off predators with spines called quills. There
are about 25 species of porcupine. About half of them are found
in Europe, Asia, and Africa. The rest are found in Central and
South America, with one species living in North America.
A North American porcupine is covered with about 30,000
long, sharp quills. The quills range from half an inch (1.3 cm) to
5 inches (12.7 cm) long. A porcupine warns enemies before they
attack. It lowers its head, lifts its tail, and raises its quills and
rattles them. It also clacks its teeth, stamps its feet, and gives off
a very strong smell from a patch of skin on its back.
If the attacker persists, the porcupine will back up toward
it and whack it with its tail. The quills, which are barbed at the
end, pop off the porcupine and stick in the attacker’s skin. They
are painful and can actually drill deeper into skin and muscles
The African crested porcupine also warns predators not to
mess with it. It shakes its tail, making a loud rattling noise with a
clump of special, hollow quills. This porcupine also raises quills
on its back that can be up to 20 inches (50 cm) long and are boldly
striped in black and white. As a last resort, it will run sideways or
backward to jab its quills into its foe.
Hedgehogs are also prickly. A European hedgehog has about
5,000 short, sharp spines. Unlike a porcupine’s quills, hedgehog
spines do not come out of the skin when used for jabbing.
A hedgehog usually flees or hides in the face of danger. If
it is cornered, it raises its spines and then rolls into a ball, protecting
its soft belly and its head. A hedgehog can stay rolled
up for many hours, and a predator is likely to give up prodding
the unresponsive, prickly ball. An uncurled hedgehog, however,
may leap backward into a predator or thrust its spiny body into
Spines also protect spiny anteaters called echidnas. Echidnas
are Australian monotremes (egg-laying mammals) that eat insects, snaring them with their long, sticky tongues. Hundreds
of spines cover an echidna’s body. A spine can be about 2 inches
(60 mm) long. If threatened, an echidna digs quickly into the
ground, leaving only its spiny back showing. It can also roll up
into a ball or wedge itself into a crevice among rocks.
The army of spiny mammals includes the spiny rats of Central
and South America. Some species of spiny rats have sturdy
spines, while others have stiff, bristly hair. Spiny rats can also
shed their tails to escape a predator’s grip. Another group of
spiny mammals, the tenrecs, is found on Madagascar, an island
off the east coast of Africa. A tenrec can roll up into a ball like a
hedgehog. It also has a powerful bite and will butt its enemy in
the neck with its spiny head.