Answers and Explanations—5.8 Turtle Navigation

P1	Paragraph 1	Comments
S1	Every 2 to 3 years, female leatherback sea turtles in their breeding years make their way to a beach, where they climb ashore to lay their eggs in the sand.	Leatherback sea turtles lay eggs on a beach every 2–3 years.
2	Like other sea turtles, leatherbacks lay these eggs in a “clutch,” or nest.
3	A single clutch can contain as many as 85 eggs, although not all of them will have been fertilized.	1 clutch = up to 85 eggs.
4	Of those that have been fertilized, however, the embryos will incubate in the sand for 50 to 60 days and then hatch, before which time the mother turtle will have already returned to the ocean.	Eggs hatch after 50–60 days.
5	The baby turtles, or “hatchlings,” collectively dig themselves out of the sand and onto the shore, where they must make their way to the sea in order to survive.	Baby turtles dig out and head toward the sea.

	According to paragraph 1, which of the following statements is true of baby leatherback turtles?	Fact. S4–5 discuss the baby turtles most directly.
✗	A They compete with each other as they make their way to the sea.	S5 states that they make their way to the sea, but never mentions anything about competition.
✗	B They hatch on top of the sand of a beach.	S4–5: “the embryos will incubate in the sand… and then hatch… The baby turtles… dig themselves out of the sand.” In other words, the baby turtles hatch in or within the sand, not on top of it.
✗	C They emerge from nests of typically just a few offspring.	S3: “A single clutch can contain as many as 85 eggs.” This number is substantially higher than “just a few.”
✓	D By the time they hatch, their mother has returned to the sea.	Correct. S4: “the embryos… hatch, before which time the mother turtle will have already returned to the ocean.”

	The word “incubate” in the passage is closest in meaning to	VOCABULARY. “Incubate” = literally, sit on eggs to keep them warm, so they can develop. More generally, “incubate” = develop or grow something at an early stage. You can also say that something “incubates” on its own, meaning that it develops or grows while it is in an early stage.
✓	A develop	Correct. “The embryos will incubate in the sand for 50 to 60 days” = they will develop in the sand for that period of time, within the eggs.
✗	B erupt	“Erupt” = break out violently. “Incubate” does not imply that speed or violence at all. Also, S4 says that the embryos incubate and then hatch, or break out of their shells.
✗	C degenerate	Opposite. “Degenerate” = become worse or weaker.
✗	D burrow	Unrelated. “Burrow” = to dig a hole or tunnel.

P2	Paragraph 2	Comments
S1	The stakes for finding the ocean quickly are extremely high.	Stakes are high.
2	Hatchlings that do not quickly make their way from the clutch into the sea will die.	Turtles that are slow die.
3	During their sprints, they are at risk of predation by myriad creatures, from crabs to birds to snakes to native predators, that dwell on beaches worldwide.	Predators.
4	They are also exposed to possible dehydration should they remain out of the water for too long.	Dehydration.

	Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.	Simplify Sentence. S3 explains one of the risks to hatchlings on their way to the ocean: predators.
✗	A As they race to the ocean, hatchings that avoid myriad predators on the beach are not at risk.	S3 presents the risk of predators. But you cannot conclude that if hatchlings avoid predators, they are not at risk. After all, S4 explains another risk (dehydration).
✗	B The primary threat to hatchlings on their way to the sea is predation by various creatures that live on the beach.	S3 does not claim that predators are the primary threat, just that they are a threat.
✓	C Numerous beach-dwelling predators are a threat to hatchlings rushing to the sea.	Correct. This rephrasing captures the essence of S3. The omission of specific examples of the predators is fine.
✗	D Upon reaching the sea, hatchlings are vulnerable to a wide range of predators that live on beaches.	S3: “During their sprints… ” That is, S3 refers to the time during which the hatchlings are sprinting toward the sea. This rephrasing incorrectly puts the threat afterwards.

P3	Paragraph 3	Comments
S1	There are several factors involved in the navigation of these newborn reptiles to the sea.	Several factors help the baby turtles navigate.
2	Light, however, is the most important factor.	Light = most important.
3	The hatchlings use visual cues to find their way into the lapping ocean water.	How that works.
4	In particular, they observe the reflection of the moon and stars in the night sky on the water, and the contrast of this reflection with the dark silhouettes of the dunes and trees on land.

	Which of the following can be inferred from paragraph 3 about the dunes and trees?	Inference. S4 describes the “dark silhouettes of the dunes and trees.” These dark silhouettes are contrasted with the brighter water, which shows “the reflection of the moon and stars in the night sky.” The turtles observe this contrast and use it to move in the right direction.
✗	A They largely fail to assist the newborn turtles in their navigation.	Opposite. Their “dark silhouettes” contrast with the brighter water to help the turtles find their way to the ocean.
✗	B By being uphill from the nests, they direct the hatchlings downhill toward the water.	The passage never mentions the difference in elevation between the ocean and the dunes or trees.
✓	C The dimness of their silhouettes causes the turtles to move away from them.	Correct. The hatchlings sprint toward the brighter “reflection of the moon and stars… on the water” (S4), which is contrasted with the “dark silhouettes of the dunes and trees.” S4 is meant to illustrate the key point of S2, which states that “light… is the most important factor” in guiding the turtles to the ocean. So you can infer that the turtles move toward the water because it is brighter, and away from the dunes and trees because they are darker or dimmer.
✗	D They reflect the light of the moon and stars more effectively than the dark ocean water does.	Opposite. S4 indicates that the reflection of the moon and stars is visible in the water, not in the dunes and trees.

P4	Paragraph 4	Comments
S1	Prior to modern times, this process was not made perilous by artificial light interfering with the turtles’ seaward orientation.	Artificial light was not a problem before modern times.
2	The turtles’ innate sensitivity and attraction to light guided them where they needed to go: into the water.
3	But nowadays, the brightest light often does not come from the moon and stars being reflected on the surface of the ocean.
4	Instead, the bright lights of the lit structures that populate many beaches draw the baby turtles in the direction opposite of where they need to go: away from the ocean.	But now, bright lights on shore can draw baby turtles in the wrong direction.
5	As a result, and particularly because the leatherback turtle has been listed as an endangered species since 1970, efforts have been made to reduce the impact of artificial light on leatherback hatchlings.	So efforts have been made to reduce this problem, especially because leatherbacks are endangered.

	According to paragraph 4, an important reason why baby turtles have difficulty nowadays navigating toward the sea is	Fact. P4 describes the modern-day problem of artificial light on shore. This light can cause the turtles to go in the wrong direction.
✓	A the presence of distractingly illuminated buildings	Correct. S4: “the bright lights of the lit structures that populate many beaches draw the baby turtles” in the wrong direction.
✗	B the diminished brightness of the moon due to air pollution	Not mentioned in the text.
✗	C the reduced influence of artificial light as a result of efforts since 1970	Opposite. S5 states that these efforts to reduce the impact of artificial light are a result of the problems described in S3 and S4.
✗	D increased threats from scavenging predators, such as birds and snakes	Threats from predators were mentioned earlier in the passage. They are not discussed in P4.

	The word “impact” in the passage is most closest in meaning to	VOCABULARY. “Impact” = influence, effect.
✗	A emphasis	“Emphasis” = importance or stress. That’s not the same as impact, influence, or effect.
✓	B effect	Correct. “Reduce the impact of artificial light on leatherback hatchlings” = reduce the effect that artificial light has on these hatchlings.
✗	C energy	Unrelated. Stamina or drive is not the same as having an effect.
✗	D esteem	Unrelated. Although someone or something with influence might also be held in high “esteem” (respected or admired), it is not necessarily the case.

P5	Paragraph 5	Comments
S1	Certain light-emitting diode (LED) lights that fall within set wavelengths have been found to interfere less with the navigation of baby turtles.	Certain lights interfere less.
2	These wavelengths are on the spectrum of light that ranges between yellow/orange and red.
3	Organizations such as the Florida Fish and Wildlife Conservation Commission have labeled these lights safe for use around turtles.	These lights have been labeled safe for turtles.
4	In cooperation with wildlife advocates and organizations devoted to the protection of sea turtles, many coastal businesses worldwide have replaced problematic light fixtures with turtle-safe lighting.	Many coastal businesses have put in these lights.

	Why does the author mention “light-emitting diode (LED) lights” in the passage?	Purpose. S1 includes the mention of these lights, which “have been found to interfere less with the navigation of baby turtles.” The description “light-emitting diode (LED)” is there to provide the name of a specific example.
✗	A To contrast LED lights with lights that interfere less with the navigation of baby turtles	LED lights are the lights that interfere less with turtles.
✗	B To suggest that LED lights be removed from existing installations near beaches	Again, these LED lights are actually the turtle-safe kind.
✗	C To argue that incandescent and fluorescent lights should not be permitted on coastal properties	These other kinds of lights are not named. More importantly, the author never suggests banning outright other kinds of lights from coastal properties.
✓	D To name a concrete example of a light that poses less of a threat to baby leatherback turtles	Correct. This concrete example in S1 allows the author to discuss the impact of this kind of lighting in the rest of the paragraph.

P6	Paragraph 6	Comments
S1	Leatherbacks are “pelagic,” meaning they live in open water (in contrast to staying near the shore or dwelling on the ocean bottom), and this includes the hatchlings; if they manage to make it to sea, they will venture into the open waters.	Leatherbacks live in open water, including the hatchlings.
2	Researchers have named the ensuing years the “lost years,” as the turtles live in the open sea and are difficult to track.	“Lost years” in the open sea.
3	They have attempted to study their whereabouts and navigation patterns by tagging baby turtles and tracking them via satellite.	Researchers have tried to study with tagging.

	The word “venture” in the passage is closest in meaning to	VOCABULARY. As a verb of motion, “venture into” something = go forward into it, usually at some risk.
✗	A be swept out	“Be swept out” would mean that the turtles are not moving on their own. “Venture” = go forward of your own free will.
✓	B set out	Correct. “They will venture into the open waters” = they will set out or go forward into those (dangerous) waters.
✗	C tumble forth	Like “be swept out,” the word “tumble” implies involuntary action, a lack of power and choice on the turtles’ part. This is not what “venture” signifies.
✗	D linger around	Opposite. “Linger” = stay, delay going forward.

P7	Paragraph 7	Comments
S1	The turtles are known for their long-distance migrations and over the years will possibly travel tens of thousands of miles.	Turtles travel very far.
2	When they are 15 to 25 years old, female leatherback turtles reach maturity and return to the different beaches where each was born to lay their own clutches of eggs.	At maturity, female returns to beach where she was born.
3	How does the mature leatherback find her way back to her natal beach, which is sometimes thousands of miles away?	How?
4	It is believed that the turtle uses the Earth’s magnetic fields to accomplish this incredible feat.	Maybe Earth’s magnetic fields, like some other traveling species.
5	This magnetic sense is the same kind of “compass” used by a number of species that also navigate long distances, including monarch butterflies, yellow-fin tuna, and sockeye salmon.

	The word “they” in the passage refers to	Reference. S2: “When they are 15 to 25 years old, female leatherback turtles… ” Here, the word “they” in the short introductory clause actually refers forward to the subject of the sentence, “female leatherback turtles.” (If that subject didn’t make sense, “they” would most likely then refer back to the subject of the previous sentence, “the turtles.”)
✓	A female leatherback turtles	Correct. S2: “When they are 15 to 25 years old, female leatherback turtles reach maturity” = when female leatherback turtles are this old, they reach maturity.
✗	B long-distance migrations	It would not make sense to say “When [long-distance migrations] are 15 to 25 years old.”
✗	C 15 to 25 years	It would not make sense to say “When [15 to 25 years] are 15 to 25 years old.”
✗	D tens of thousands of miles	It would not make sense to say “When [tens of thousands of miles] are 15 to 25 years old.”

	According to paragraph 7, which of the following is likely to be the method by which the adult female leatherback finds her way back to the beach where she was born?	Fact. S3 essentially asks this same question. S4–5 provide the answer.
✗	A Eventually reaching maturity	S2 mentions that once the turtles reach maturity, they return to the beaches where they were born. But reaching maturity is not presented as the method. S3 poses the question of how this navigation is done, and S4–5 provide the answer.
✓	B Using the Earth’s magnetic fields	Correct. S4–5 describe how the female turtle “uses the Earth’s magnetic fields to accomplish this incredible feat” = find her way back to her natal beach, according to S3.
✗	C Tracking yellow-fin tuna and sockeye salmon	S5 mentions these fish as examples of other species that likely use a magnetic “compass” as well.
✗	D Laying her own clutch of eggs	For the turtle, this is not the method of finding her way back. This is the goal of finding her way back.

P7	Paragraph 7	Comments
S1–2	The turtles are known for their long-distance migrations and over the years will possibly travel tens of thousands of miles. When they are 15 to 25 years old, female leatherback turtles reach maturity and return to the different beaches where each was born to lay their own clutches of eggs.
3	A How does the mature leatherback find her way back to her natal beach, which is sometimes thousands of miles away?	S2 does not list different species of animals that could be referenced by the key phrase “such as these.”
4	B It is believed that the turtle uses the Earth’s magnetic fields to accomplish this incredible feat.	Likewise, S3 does not list different species of animals that could be referenced by the key phrase “such as these.”
5	C This magnetic sense is the same kind of “compass” used by a number of species that also navigate long distances, including monarch butterflies, yellow-fin tuna, and sockeye salmon.	Likewise, S4 does not list different species of animals that could be referenced by the key phrase “such as these.”
End	D	Correct. Finally, S5 contains the critical list: “a number of species that also navigate long distances, including monarch butterflies, yellow-fin tuna, and sockeye salmon.” The inserted sentence fits here.

	An ability to perceive magnetic fields is in fact shared by animals such as these that may otherwise be quite different from one another. Where would the sentence best fit?	Insert Text. The telling phrase in the inserted sentence is “animals such as these.” This phrase indicates that the previous sentence must list types of animals that have an ability to perceive magnetic fields and that “may otherwise be quite different from one another.”
✗	A Choice A
✗	B Choice B
✗	C Choice C
✓	D Choice D	Correct.

	Whole Passage	Comments
P1	Every 2 to 3 years, female leatherback sea turtles in their breeding years make their way to a beach…	Leatherback sea turtles lay eggs on a beach every 2–3 years. 1 clutch = up to 85 eggs. Eggs hatch after 50–60 days. Baby turtles dig out and head toward the sea.
P2	The stakes for finding the ocean quickly are extremely high…	Stakes are high. Turtles that are slow die. Predators. Dehydration.
P3	There are several factors involved in the navigation of these newborn reptiles to the sea…	Several factors help the baby turtles navigate. Light = most important. How that works.
P4	Prior to modern times, this process was not made perilous by artificial light…	Artificial light was not a problem before modern times. But now, bright lights on shore can draw baby turtles in the wrong direction. So efforts have been made to reduce this problem, especially because leatherbacks are endangered.
P5	Certain light-emitting diode (LED) lights that fall within set wavelengths have been found to interfere less…	Certain lights interfere less. These lights have been labeled safe for turtles. Many coastal businesses have put in these lights.
P6	Leatherbacks are “pelagic,” meaning they live in open water…	Leatherbacks live in open water, including the hatchlings. “Lost years” in the open sea. Researchers have tried to study with tagging.
P7	The turtles are known for their long-distance migrations…	Turtles travel very far. At maturity, female returns to beach where she was born. How? Maybe Earth’s magnetic fields, like some other traveling species.

	Select from the five phrases below THREE that characterize the behaviors of leatherback turtles and TWO that characterize the behaviors of people, according to the passage.	Table. Unfortunately, the passage is not neatly divided according to these two categories. Using the knowledge you’ve gained from reading the passage and answering questions so far, try to classify the answers without necessarily finding proof. Only go back to the passage if you are stuck.
	a Following reflective light on the ocean’s surface	Turtles. P3 describes this turtle behavior.
	b Using magnetic fields for navigation	Turtles. P7 describes this turtle behavior.
	c Advancing the use of certain kinds of artificial light	People. P4 describes how people are making efforts to replace artificial lighting hazardous to turtles with other kinds of artificial light that is more turtle-friendly.
	d Tagging and tracking maturing leatherbacks	People. P6 describes this human behavior.
	e Responding less to certain wavelengths of light and more to other wavelengths	Turtles. P5 describes certain kinds of lights that are safer for turtles. It is strongly implied that these lights are safer because the lights “fall within set wavelengths.” So the turtles must respond to those wavelengths less than they do to the wavelengths in typical lights.