98 Nature
FIND OUT MORE. Digestion 144–145 • Plants 88–89 • Teeth 143
4 TOUCAN
Some birds, such as the toucan,
specialize in eating fruit. Packed
with sugars, fruit is much more
nourishing than leaves and far
easier to digest. However, it is
also more scattered and harder
to find. Many fruit-eating birds
sometimes have to eat insects. It
is only in tropical rainforests that
birds can find fruit all year round.4 SCAVENGERS
Hyenas and vultures are scavengers – meat-eaters that get their
food from the abandoned kills of others. This zebra was killed by
lions, which have already eaten their fill and left.TOOTHY GRIN 3
A shark’s teeth are sharp and
pointed to rip prey to pieces. They
grow in rows and are continually
shed and replaced. Some species
may get through as many as
30,000 teeth in a lifetime. Not all
sharks are predators – the largest,
the whale shark, is a filter-feeder.GRIZZLY BEAR 3
Bears eat many
foods, including
fruit, nuts, roots,
honey, carrion (dead
animals), small mammals,
and salmon swimming
upriver, as shown here.CARNIVORES
Most carnivores are predators – animals that hunt other animals
for food. Predators usually have sharp teeth, claws, or beaks to
tear apart their prey. Animal flesh is nourishing, so predators
do not have to kill very often. It is also easy to digest.HERBIVORES
The jaws, teeth, and stomachs of herbivores are designed to
tackle tough plant food. Compared with meat, plants are not
very nourishing, so many herbivores spend long hours feeding.Feeding
All animals must eat other organisms to survive.
Animals can be divided into two main groups,
according to their feeding habits:. CARNIVORES
(meat-eaters) and. HERBIVORES (plant-eaters).
WHAT IS AN OMNIVORE?
Most animals eat either meat or plants, but omnivores
eat both. The word omnivore means “everything-eater”.
Bears and pigs are omnivores – so are humans. In our
diet we carry on the traditions of our early ancestors,
who killed game and also gathered berries and nuts.WHAT IS FILTER-FEEDING?
This feeding method works by sifting large amounts
of small organisms from water. It is a bit like using
a sieve to catch prey. Filter-feeders come in a variety
of shapes and sizes – barnacles, flamingos, and baleen
whales (including the blue whale) all feed in this way.HOW DO PREDATORS KILL THEIR PREY?
Top predators such as lions, sharks, and eagles rely on
strength and speed to overcome their victims. Smaller
or weaker hunters may rely on stealth or special
techniques to capture prey. Some predators, such as
wolves, hunt in packs. Spiders spin webs to tangle
up victims. Rattlesnakes kill their prey with venom.HOW DO HERBIVORES DIGEST THEIR FOOD?
Plants contain tough cellulose, which is hard to digest.
Many herbivores’ stomachs are filled with microbes,
which break down cellulose. Some plant-eaters, such
as cattle, have stomachs with several chambers. After
passing through some chambers, food is returned to
the mouth for more chewing to help break it down.HOW DO HERBIVORES AVOID CARNIVORES?
Herbivores do not need quick wits to capture their
food, but they must be swift or have some means of
defence to avoid being eaten by predators. Many are
camouflaged to blend in with their surroundings, so
that hunters do not notice them. Others have tough
skin, spines, or even poison to put off enemies.Toucan’s bill is extra-large for
probing through vegetationy.
feeding