Download Getting to Know: Endangered Species

Getting to Know: Endangered Species
There are almost 7 billion humans on Earth, and our population continues to grow. However, many plant and animal populations are declining. In fact, many thousands of plants and animals are listed as endangered species. For example, many primates are endangered, including the chimpanzee, our closest relative.
What does it mean if a species is
endangered?
An endangered species is one whose population
is so small that it may not be able to produce
The chimpanzee is one of many endangered
species.
enough offspring to survive. These species can
become extinct when none of the individuals in
the species can survive to reproduce. The fossil record is full of extinct species from the past,
and additional species are also becoming extinct today.
What can happen when a species goes extinct?
When a species goes extinct, it disappears forever. In a few cases, the impact can be minor.
Another species might occupy the vacant ecological niche. In other cases, the impact can be
widespread. If a predator species becomes extinct, prey populations may explode in great
numbers. Such changes can ripple across the food web.
What kinds of animals are endangered?
Large animals typically have smaller populations than small ones, so they are more likely to
become endangered. Some animals have very specific habitat requirements. A bird might be
found only in a small valley. A fish might be found only in one river. If the valley is deforested
or if the river is dammed, those species can quickly become endangered.
Animals with properties that are attractive to humans are more likely to be hunted. If their
populations are limited, they may become endangered as a result. Some animals such as
the rhino are incorrectly thought to have medicinal properties and are hunted for medicine.
Animals with attractive skins or feathers are also more likely to be hunted.
Misconception 1: Even if species are lost, there are plenty of animals. Why is it
important if a species is lost?
The extinction of a species affects all the living things to which it is connected. Species
loss can also indicate environmental problems that could also affect humans.
Concept: Endangered Species
Getting to Know
www.discoveryeducation.com
1
© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.
What causes a species to become
endangered?
Anything that reduces the population of a species can cause it to become endangered. These factors include its population size, ecology, value to humans, and other influences. The most common threat to species is habitat loss. This may occur through deforestation or urbanization. Other threats include hunting or poaching, overfishing, and pollution.
There are different categories of endangered species. These include Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, and Extinct. With the help of conservation programs, species can regain numbers. For example, a captive breeding program might help a species change status from Extinct in the Wild to Endangered.
The rhino is endangered because
it is hunted for its horn.
Who decides whether or not a species is endangered?
Sometimes people debate whether or not a species is endangered. In the United States,
the law protects endangered species. Such protection can limit economic activities. In such
cases, a compromise is often reached. To determine the status of a species, scientists study
factors influencing its population trends. Worldwide, the International Union for Conservation
of Nature keeps a list of endangered animal species called the Red List. There are currently
approximately 3,700 species on that list.
Misconception 2: We never see species being lost, so how do we know this is
happening?
The loss of species is well recorded by ecologists and conservation biologists who make
regular counts of species in their native habitats. Loss of species may be gradual, but it is
happening. In the midwestern United States, at least 15 species of birds and plants have
become extinct in the past couple of centuries.
This seems depressing. Why should I care?
All species are part of the world’s biological diversity. Such biodiversity is a measure of the
variety of plants and animals in an area. We depend on biodiversity to keep ecosystems
healthy. A variety of species is needed to help clean the air and water, remove pollutants, and
provide us with wild-caught food such as fish. Many rare plants and animals also hold cures to
human diseases. Wild species are beautiful and interesting. They have their own right to exist.
There are more endangered species today than ever before. Scientists worry that Earth is
undergoing a mass extinction of species. We have little idea of the long-term consequences of
such a mass extinction. You will learn more about what people can do to protect endangered
species and Earth’s biodiversity in the lesson, so let’s get started!
Concept: Endangered Species
Getting to Know
www.discoveryeducation.com
2
© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.