Passage 2: Unwanted Guests: The Dangers of Invasive Species (2016)

Groups of different animals affect one another in the natural world. For example, imagine that wolves and deer live in an area. A certain number of wolves need to eat a certain number of deer to survive. This keeps the population of the deer from getting too big. Similarly, the deer eat grass and vegetation. If there were more deer, they’d need to eat more grass.

The natural world is full of balances like these. Unfortunately, sometimes these balances are upset by invasive species. An invasive species is an animal or plant that has moved or been moved from its original environment to a new one. It has established a stable population there that is causing problems. Invasive species don’t cause problems in their original environments because they are kept in check by other plants and animals. In new environments, though, they have nothing stopping them from taking over.

One example of an invasive species is the zebra mussel. This animal originally only lived near Russia. Zebra mussels got into the Great Lakes by attaching themselves to the bottoms of ships. They now live in the Great Lakes too, where they upset the ecosystem. Zebra mussels eat algae, but so do fish. Many fish die as a result of there not being enough algae for all the animals to eat.

Plants can be invasive species too. Another example of an invasive species is the kudzu vine. Humans introduced the plant to the United States on purpose. Farmers were encouraged to grow it to protect their soil. Since then, it has gotten out of control. It now covers large parts of the South, outcompeting native plants for resources like water and sunlight.

Invasive species can cause environmental problems that are very difficult to fix. Because of this, it’s important to rethink introducing any species to a new environment. It’s also important to check to make sure when traveling that you are not bringing any plants or animals with you!

How does the story of how the zebra mussel became an invasive species differ from the story of how the kudzu vine became an invasive species?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

According to passage 1, what is the main threat for frogs and toads?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

 According to passage 1, why are frogs being born with extra legs?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

What does passage 1 say is happening to frogs as their habitats are being destroyed?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

What does passage 1 say about how pollution is affecting frogs?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

Based on what you read in passage 2, what is a conservation biologist?

Passage 1

Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land, and have backbones. Amphibians must live near water. Amphibians are in trouble because their habitat is being destroyed as trees are being cut down to make room for farms and roads. Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. 

Scientists are working to save amphibians from their plight. Scientists want the government to pass laws that protect amphibian habitats and limit pollution. 

Passage 2

My name is Maria and I am an amphibian conservation biologist. My job is to protect amphibians and their natural habitats, develop educational programs and exhibits to engage the public about amphibian conservation, and research to develop tools that will allow scientists to reintroduce amphibians back into the wild. Conservation biologists are scientists who study and protect animals and their environments.  I work in a zoo, but I often travel to places like Ecuador or Brazil to observe a variety of amphibians in their natural habitats. Brazil, for example, has 1,022 different types of frogs, toads and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats were destroyed.  We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda,  to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws like the Endangered Species Act that protect wildlife and their homes. She, in turn, needs to partner with government workers who can lobby and vote to help get laws passed. Together, our goal is to work together to build a world where these amphibians have safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build protected space for amphibians to be released from the zoo and into a space where they can thrive.

What sentence from passage 2 best supports the idea that conservation biologists want to return amphibians to the wild?

Mars, an orange-red planet often visible in the night sky, has long been studied by humans. In the past, scientists used telescopes to chart the movements of Mars. Modern scientists study the planet in more detail using tools and instruments in addition to telescopes. NASA has a Mars Exploration Program to try to understand whether Mars was, is, or can be, a habitable world. 

What sentence from the passage best describes how scientists today study Mars?

Mars, an orange-red planet often visible in the night sky, has long been studied by humans. In the past, scientists used telescopes to chart the movements of Mars. Modern scientists study the planet in more detail using tools and instruments in addition to telescopes. NASA has a Mars Exploration Program to try to understand whether Mars was, is, or can be, a habitable world. 

Based on the passage, what is the Mars Exploration Program trying to find out?

Mars, an orange-red planet often visible in the night sky, has long been studied by humans. In the past, scientists used telescopes to chart the movements of Mars. Modern scientists study the planet in more detail using tools and instruments in addition to telescopes. NASA has a Mars Exploration Program to try to understand whether Mars was, is, or can be, a habitable world. 

What does the passage tell you about why scientists used to study Mars?