H
ave you ever heard the expression, "If you scratch
my back, I'll scratch yours?" That's how symbiosis
works. The word symbiosis comes from the Greek
word meaning "life together" and there are three
varieties: parasitism, mutualism, and commensalism.
When one organism is hurt by the relationship and the
other is helped, that's parasitism. When both benefit
from the deal, it's mutualism. When one benefits, but the
other isn't affected, it's commensalism. Can you figure
out what type of symbiotic relationship these organisms
have? Flip the page upside down to check your answers.
Ticked Off?
You'll find oxpeckers hanging around on Cape
buffalo, rhinoceroses, elephants, antelopes,
giraffes, and other large herbivores. These redand-yellow billed birds piggy-back on the animal
or hang from its body. As they ride, oxpeckers
peck off ticks, leeches, flies, and other pests from
their animal pals. If there's danger coming, and the
animal doesn't react fast enough, the oxpecker flies
up to the animal's head and pecks on its skull. The
rhino does its part for the oxpecker, too. This bird
would die if it couldn't eat herbivore blood that
had first been passed through a tick.
Getting a
Free Ride
Remoras have specially
shaped suction cups
on top of their
heads.
When a
shark, ray,
turtle, or
other creature
swims by, the
remora sucks
itself onto the
animal. In addition to getting a free
ride through the waters, the remora uses
the animal for protection against other predators.
As a shark eats, the remora swims near it, eating
up scraps and bits of food. But this is a give-andtake relationship: Remoras nibble up parasites,
barnacles, and leeches from its host's skin.
Sweet as
Honeydew
When a large blue butterfly caterpillar molts, its
body falls to the ground. Within minutes, red ants
have it surrounded. The ants stroke the
caterpillar until it pushes out honeydew for the
ants to drink. Then, the ants carry the
caterpillar to their nest until it's ready to turn
into a butterfly.
While in the ant's
nest, the caterpillar
gets lots of food—
baby ants. It would
die without ant larvae
to munch on. The ants
don't mind one bit: the
caterpillar pumps out a
huge supply of honeydew for '
the ants to drink.
Thanks for
Nothing
Tropical orchids are beautiful
flowers—and they have trees to
thank. Trees provide the orchids with a
sunlit living space—and the orchid doesn't
have to do anything in return.
Clowning Around
Sucker!
Dogs itch to get rid of fleas—and so does
every other animal that has them. The critters
live on or inside an animal's body and suck
nutrients from it. An
animal that has fleas
loses lots of
fluid—such as
blood—
because of
these
Though other fish get stung by a sea anemone's tentacles,
clownfish live in harmony with them. In return for shelter,
clownfish lure other fish near the anemone's
tentacles. The poison in the tentacles^
stings and stuns the prey. It's
lunchtime for the clownfish—
and the anemone.
Activity
C A N Y O U R E L A T E ? Make a list of other
common symbiotic relationships. Next to
each organism in the relationship, indicate
if it is helped or hurt. Use a + sign if the
organism is helped, a - sign if the organism
is harmed, and a 0 to show that it is neither
helped nor harmed.
DISCOVERY EDUCATION SCIENCE C O N N E C T I O N