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Endangered Species and the Sixth Extinction — Reading Comprehension

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MS-LS4-1
MS-LS2-5

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This engaging science reading passage for grades 6-8 explores the current biodiversity crisis, known as the 'Sixth Extinction.' Students will discover how extinction rates today are 100 to 1000 times higher than normal, mainly due to human activities summarized by the HIPPO acronym: Habitat loss, Invasive species, Pollution, Population, and Overexploitation. The passage describes past mass extinctions, explains how scientists measure extinction, and features real-world case studies such as the California condor and vaquita porpoise. It also highlights conservation laws like the Endangered Species Act and international efforts such as the IUCN Red List. Success stories and the debate over de-extinction are included, helping students analyze cause and effect in ecosystems. This resource aligns with NGSS standards MS-LS4-1 and MS-LS2-5, supports audio integration, and includes a glossary, quiz, writing prompts, and graphic organizers to reinforce key concepts.

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endangered-species-1 — Many species in diverse habitats are at risk due to the impacts of climate change

Earth’s biodiversity is facing a crisis unlike any in millions of years. Every year, scientists record the disappearance of species at rates far higher than the background extinction rate, which is about one species per million species per year under normal conditions. Today, extinction is happening 100 to 1000 times faster, driven mainly by human activities. This rapid loss of species is called the Sixth Extinction, and it threatens the stability and health of ecosystems worldwide.

The Mechanisms Behind Mass Extinction

Mass extinction events have occurred five times before in Earth’s history. For example, the Permian extinction wiped out around 90% of species, and the Cretaceous extinction ended the reign of the dinosaurs. What makes the current crisis different is its cause. Scientists use the acronym HIPPO to describe the main human-driven factors: Habitat loss, Invasive species, Pollution, Population growth, and Overexploitation. Each of these alters natural systems in complex ways. For instance, when forests are cleared for farms or cities, animals lose their homes and food sources. Invasive species can outcompete native species, while pollution can poison water and soil. Human population growth increases demand for resources, and overexploitation—like overfishing or illegal hunting—can push species to the brink of extinction.

Measuring and Responding to the Crisis

Scientists use tools like the IUCN Red List to assess which species are at risk. In the United States, the Endangered Species Act provides legal protection for species categorized as "endangered" or "threatened." Notable examples of species on the brink include the California condor, the black-footed ferret, the vaquita porpoise, and the Sumatran rhino. For some, conservation efforts have made a difference. The bald eagle, gray wolf, and humpback whale were once in danger but have recovered thanks to targeted protection and habitat restoration. These success stories show that human action can reverse declines, but prevention is usually easier than recovery.

Complexities and the Future of Biodiversity

The biodiversity crisis affects not just individual species but entire ecosystems and the services they provide, such as clean air, water, and food. Scientists also debate new technologies like de-extinction, which might one day bring back extinct species like the woolly mammoth or passenger pigeon. However, most agree that conserving existing species and habitats is the most effective way to maintain the intricate balance of life on Earth. Solving the Sixth Extinction will require international cooperation, science-based policies, and public awareness.

Our understanding of this crisis comes from collecting data, analyzing patterns, and using systems thinking to connect human actions to ecological outcomes. By learning from both past mass extinctions and recent conservation successes, we can make choices that help protect the planet’s rich diversity for the future.

Interesting Fact: The vaquita porpoise is the world’s rarest marine mammal, with fewer than 10 individuals remaining in the wild.

What is the main cause of the current high rate of species extinction?

Human activitiesVolcanic eruptionsMeteor impactsNatural climate changes

What does the acronym HIPPO stand for?

Habitat loss, Invasive species, Pollution, Population, OverexploitationHeat, Ice, Pollution, Predators, Oxygen lossHabitat, Insects, Plants, Predators, OceansHunting, Industry, Pollution, Parks, Overfishing

According to the passage, how does the current extinction rate compare to the background extinction rate?

It is 100 to 1000 times higherIt is the sameIt is much lowerIt happens only once every million years

What is the role of the IUCN Red List?

To assess which species are at risk of extinctionTo create new speciesTo measure water qualityTo count human populations

Which of the following is a success story where a species was brought back from the edge of extinction?

Bald eagleVaquita porpoiseSumatran rhinoPassenger pigeon

What does 'de-extinction' mean as used in the passage?

Bringing extinct species back to lifeProtecting endangered speciesCounting animal populationsDestroying invasive species

Why is prevention of extinction usually easier than recovery, according to the passage?

It is easier to protect species before their numbers are very lowIt costs less moneyIt does not require lawsIt requires less scientific research

Which of the following is NOT listed as a current example of a species on the brink of extinction?

Passenger pigeonCalifornia condorVaquita porpoiseSumatran rhino