Endangered Species and Extinction SPI 3210.2.6 SPI 3210.2.7

Extinct Extinct: when a species permanently disappears from Earth. Here are some organisms, throughout Earth’s history, that have gone extinct:

Extinction The disappearance of a species or larger group of organisms. 1). Occurs naturally over time 2). Results from a change in the environment Conditions changes, organisms living the affected area may not be able to adapt quickly enough to survive the change. If they can not migrate to a suitable area, they will die out.

Extinction example A population of birds or trees living next to the ocean can be killed off by a hurricane. If that organism does not live anywhere else, the species becomes extinct.

Dinosaurs Extinction Most scientist believe: Sudden, drastic change caused the extinctions of ¾ of the species on Earth, including all the large dinosaurs 65 million years ago. Asteroid or comet collided with Earth in what is now the Gulf of Mexico. Collision caused a huge dust cloud that blocked sunlight all over the planet. As a result: plants had difficulty making food for several years, and some became extinct. Many plant-eating animals also became extinct, because they could not find food. Some also believe the collision causes huge tsunamis and forest fires, which may have killed the entire populations of some species.

Dinosaurs Extinction continued Other scientist believe: The impact was not the main cause of the extinction. Instead, a large number of volcanoes erupted over 1,000’s of years and changed Earth’s climate. Large numbers of species died out because they, or the organisms they fed on, were not able to adapt to the colder climate. Argue: The impact happened after many dinosaurs and other species had already become extinct. Overall: - all scientist agree that changes in the environment caused the extinctions

Modern Day Extinctions Extinction is increasing in today’s world. (It is a natural process) Extinction is tied to human activities. –The destruction of habitats. Habitat : place where an organism lives (particular place)

Habitat destruction by humans Forest are being cut down or cleared to provide wood or to make space for housing or farming. (deforestation) Grasslands are overgrazed. Without vegetation, the land is at risk of erosion and desertification. (endangers both plants and wildlife) Wetlands are being drained or filled in to make more land available for human use Pollution of land and water can also make habitats unsuitable for many organisms

Direct threats to species Hunting and fishing Hunting for food led to the extinction of the dodo bird, which lived only on the island of Mauritius. Hunting the American bison (almost wiped out population) Other animals hunted for certain body parts: Elephants, Rhinos All this leads to……endangered species when organisms are hunted and killed at a rate that exceeds their ability to reproduce

Endangered species Endangered species : A species whose population size is so low that it is at risk of extinction. Most species are endangered by habitat loss In recent years, people and governments around the world have made an effort to identify endangered species. Once endangered species are identified, efforts can be made to protect them.

How can endangered species be protected? Governments can protect suitable habitat, preventing hunting and development in that area Ex). Protecting a forest or other wild area can protect several species that live in that area Ex). Protect migratory birds: have to protect summer and winter habitats

Common causes of Extinction Hunting Introduction of new species habitat destruction Ex). Introduction of new species Snakes were introduced to many Pacific islands in the 20th century. Birds on those islands had built their nests on the ground. The snakes ate the eggs from those nests, wiping out some bird species.

Ticket Out (1) What does endangered species mean? (2) Name me 2 endangered species we talked about today in class