READ THE PASSAGE AND ANSWER THE QUESTIONS THAT
FOLLOW.
Six tons of pure power whacks an ice floe floating in cold Arctic waters. The seal
lying on top of the ice doesn't stand a chance. Knocked into the sea, the seal
becomes a meal for one of the ocean's top predators–the huge orca, or killer whale.
Orcas hunt everything from fish to walruses, seals, sea lions, penguins, squid, sea
turtles, sharks, and even other kinds of whales. Depending on the season and
where they are, their diet varies - some orcas eat more fishes and squid than seals
and penguins. But wherever they are in any of the world's oceans, average-sized
orcas may eat about 500 pounds (227 kilograms) of food a day. Orcas have many
hunting techniques, and bumping seals off ice is just one of them.
Often referred to as wolves of the sea, orcas live and hunt together in cooperative
pods, or family groups, much like a pack of wolves. They work together as they
hunt. Groups of orcas cooperate to herd fish into a compact area so that they're
easier to eat. They will also slap their tails onto the water's surface, causing a
wave to wash prey, such as penguins or sea lions, off ice floes and into the water.
Sometimes, a pod of whales will join forces to surround a larger animal, such as
a blue whale. They chase, bite, and wear it down until it becomes a meal.
Orcas' teeth, numbering about 45 and each measuring about 3 inches
(7.6 centimetres) long, are shaped for ripping and tearing prey. Orcas do not chew
their food. They can swallow small seals and sea lions whole. The prey easily slides
down the orcas' throats. Bigger prey is eaten in chunks. Ocras' backs are black
and their stomachs are white. Animals looking down on an orca from above, such
as a seal on an ice floe, might not see it because the whale's dark back blends
with the water below. On the other hand, the whale's white underside blends
with the light streaming down into the sea from the surface, making it hard to
be spotted from below. The colour pattern of orcas help them sneak up on their
prey and attack them. With orcas camouflaged so well, those prey fish, penguins
or seals are likely to miss the danger heading their way, as the killer whale once
again proves it is the oceans' superbly designed hunter.
How is it possible for orcas to camouflage in the sea water?
A Their dark back and white underside hide them well from their preys above and below
the water.
B The orcas like to chase, bite and wear their preys down.
C They have many hunting techniques.
D They are the ultimate killing machine; they do not need to camouflage.
