Fleas are perfectly designed by
nature to feast on anything containing blood. Like a shark in the water or a
wolf in the woods, fleas are ideally equipped to do what they do, making them
very difficult to defeat. The bodies of these tiny parasites are extremely
hardy and well-suited for their job.
A flea has a very hard exoskeleton,
which means the body is covered by a tough, tile-like plate called a sclerite.
Because of these plates, fleas are almost impossible to squish. The
exoskeletons of fleas are also waterproof of fleas are also waterproof and shock
resistant, and therefore fleas are highly resistant to the sprays and chemicals
used to kill them.
Little spines are attached to his
plate. The spine the flea scurries through an animal’s fur in – search of
grooming pet tries to pull a flea off through the hair coat, these spines will
extend and stick to the fur like Velcro.
Fleas are some of the best jumpers
in the natural world. A flea can jump seven inches, or 150 times its own
length, either vertically or horizontally. An equivalent jump for a person
would be 555 feet, the height of the Washington Monument. Fleas can jump 30,000
times in a row without stopping, and they are able to accelerate through the
air at an incredibly high rate – a rate which is over ten times what humans can
withstand in an airplane.
Fleas have very long rear legs with
huge thigh muscles and multiple joints. When they get ready to jump. They fold their
long legs up and crouch like a runner on a staring block. Several of their
joints contain a protein called resilin, which helps catapult fleas into the
air as they jump, similar to the way a rubber band provides momentum to a
slingshot. Outward facing claws on the bottom of their legs grip anything they
touch when they land.
The adult female flea mates after
her first blood meal and begins producing eggs in just 1 to 2 days. One flea
can lay up to 50 eggs in one day and over 2,000 in her lifetime. Flea eggs can
be seen with the naked eye, but they are about the size of a grain of salt. Shortly
after being laid, the eggs begin to transform into cocoons. In the cocoon
state, fleas are fully developed adults, and will hatch immediately if
conditions are favorable. Fleas can detect warmth, movement, and carbon dioxide
in exhaled breath, and these three factors stimulate them to emerge as new
adults. If the flea does not detect appropriate conditions, it can remain
dormant in the cocoon state for extended periods. Under ideal conditions, the
entire life cycle may only take 3 weeks, so in no time at all, pets and homes
can become infested.
Because of these characteristics,
fleas are intimidating opponents. The best way to control fleas, therefore, is
to take steps to prevent an infestation from ever occurring.
The primary purpose of the passage
is to
Philadelphia is a city known for
many things. It is where the Declaration of independence was signed in 1776,
and it was also the first capital of the United States. But one fact about Philadelphia
is not so well-known: it is home to nearly 3,000 murals painted on the sides of
homes and buildings around the city. In fact, it is said that Philadelphia has
more murals than any other city in the world, with the exception of Rome. How
did this come to be?
More than 20 years ago, a New
Jersey artist named Jane Golden started a program pairing troubled youth with
artists to paint murals on a few buildings around the city. Form this small
project, something magical happened. The young people involved helped to create
magnificent pieces of art, but there were other, perhaps more important
benefits. The young people learned to collaborate and get along with many
different kinds of people during the various steps required to paint and design
a mural. They learned to be responsible, because they needed to follow a
schedule to make sure the murals were completed. They also learned to take pride
in their community. It is hard for any resident to see the spectacular designs
and not feel proud to be a part of Philadelphia.
Take a walk around some of the
poorest neighborhoods I Philadelphia, neighborhoods full of broken windows and
littered front steps, and you will find beautiful works of art on the sides and
fronts of buildings. Of course they murals are not just in poor neighborhoods,
but more affluent ones as well. Special buses take tourists to different parts
of the city to see the various murals, which range from huge portraits of
historical heroes, to cityscapes, to scenes depicting the diverse ethnic groups
that call Philadelphia home.
As a result of its success, the
mural program created by Jane Golden has now become the nation’s largest public
art program and a model for to troubled youth.
As used in paragraph 1, the phrase
“it is said” suggests that the author is
