FRIDAY JULY 13

READING # 3
Some people say that the best defense is a good offense; an octopus, however, would
disagree. In addition to being one of the strangest and most beautiful creatures in nature, the
octopus has some of the most inventive and effective defense mechanisms imaginable. While
other animals have teeth, horns, or claws to help defend them from predators, the octopus
concentrates its energy on hiding from and confusing its attackers. When it wants to get away,
the octopus has an impressive arsenal of tricks at its disposal.
The most well-known of the octopus’s defense mechanisms is its ability to squirt clouds
of ink into the water. Some octopi use this cloud of ink as camouflage; after squirting the ink, the
octopus retreats into the ink cloud where the predator cannot see it. Other octopi use the ink
cloud as a decoy. If a large, intelligent predator such as a shark knows that octopi use ink
clouds for camouflage, it might simply attack the ink cloud blindly, hoping to make contact with
the octopus inside. However, some sneaky octopi will release the ink cloud in one direction and
scurry away in another direction, leaving the predator with nothing but a mouthful of ink. In
addition to confusing predators’ sense of sight, these ink clouds also confuse their sense of
smell. The ink is composed primarily of melanin (the same chemical that gives human skin its
color), which can shut down a predator’s sense of smell. If an octopus cannot be seen or
smelled, it has a much higher chance of escaping an attack.
Another defense mechanism possessed by many octopi is the ability to change color,
much like a chameleon. Most animals get their skin color from chemicals in the skin called
chromatophores (melanin is one of these chromatophores). Chromatophores might contain
yellow, orange, red, brown, or black pigments, and the amount of each pigment present in the
skin determines an animal’s color. While most animals are always the same color, some
species of octopi can control the amount of each color pigment in their skin cells, allowing them
to change color. Some poisonous octopi, when provoked, will change their skin to a bright, eyecatching color to warn predators that they are dangerous and ready to strike. Other octopi use
this ability to change their skin to the color and texture of seaweed or coral, allowing them to
blend in with their environment. Finally, some octopi—such as the mimic octopus—use this
color-changing ability to masquerade as another type of animal. The body of an octopus is
highly flexible, and some species can combine this flexibility with their color-changing skills to
make themselves resemble more dangerous animals such as sea snakes or eels.
Yet another defense mechanism possessed by some octopi is the ability to perform an
autotomy, or self-amputation, of one of their limbs and regrow it later. Many species of skink and
lizard also possess this ability, which allows them to shed their tails when caught by a predator
and therefore get away. When a predator catches a tentacle the octopus can amputate this
tentacle, thereby unfettering itself, and regrow the tentacle later. Some octopi, however, are
even cleverer. When threatened by a predator, these octopi will shed a tentacle before being
attacked in the hope that the predator will go after the detached tentacle rather than the octopus
itself.
While the octopus may not be the most vicious creature in the ocean, its numerous and
clever defense mechanisms help it to survive in the dangerous undersea world.© Copyright EnglishForEveryone.Org, 2012. All rights reserved.
Questions
1) Which of the following sentences from the passage best expresses the main idea?
A. The most well-known of the octopus’s defense mechanisms is its ability to squirt clouds
of ink into the water.
B. Some people say that the best defense is a good offense; an octopus, however, would
disagree.
C. Another defense mechanism possessed by many octopi is the ability to change color,
much like a chameleon.
D. When it wants to get away, the octopus has an impressive arsenal of tricks at its
disposal.
2) The author claims in paragraph 1 that an octopus would disagree with the statement “the
best defense is a good offense” because
A. octopi employ more defensive than offensive capabilities
B. octopi possess good defensive and offensive capabilities
C. octopi can protect themselves from teeth, horns, and claws
D. not all octopi possess the same defense mechanisms
3) Which of the following statements best describes the organizational structure of paragraphs
2-4?
A. The author lays out several reasons to support the argument that the octopus has the
best defense mechanisms of any sea creature.
B. The author devotes one paragraph each to explaining three different defense
mechanisms possessed by the octopus.
C. The author devotes one paragraph each to highlighting three potential threats to the
octopus and how the octopus deals with each one differently.
D. The author compares and contrasts three different defense mechanisms employed by
the octopus.
4) According to the passage, which of the following statements about the chemical melanin are
true?
I. An octopus’s ink is composed primarily of melanin.
II. Melanin is a chromatophore.
III. Like the octopus, chameleons use melanin to change color.
A. I only
B. I and II only
C. II and III only
D. I, II, and III© Copyright EnglishForEveryone.Org, 2012. All rights reserved.
5) As used in paragraph 4, which of the following is the best synonym for unfettering?
A. freeing
B. regrowing
C. amputating
D. sacrificing
6) The final paragraph can best be described as a
A. prediction conclusion, in which the author looks toward the future
B. full circle conclusion, in which the author incorporates and builds on a word or theme
from the introduction
C. solution conclusion, in which the author proposes a solution to a problem posed earlier
in the passage
D. summary conclusion, in which the author restates the passage’s main idea