العلوم

Extinction

Lesson objectives:

By the end of this lesson, the student should be able to:

1- Define the concept of extinction.

2-Using fossils to indicate extinction of some types of organisms.

3- Imagine the concept of extinction by reading the fossil record.

4- Conclude the factors that cause extinction of some types of living organisms.
5-Take responsibility in reducing rates of environmental pollution.

6- Understand the effect of climatic changes and natural disasters on ecological equilibrium.

7-Give examples of extinct and endangered species.

8- Protect the endangered living organisms.

9-Treat the environment with consciousness and appreciate the importance of natural life.

10- Understand the effect of extinction on ecological equilibrium.

11-Respect the value and role of living organisms in the ecological equilibrium.

12-Suggest new solutions to protect living organisms from extinction.

13-Deal gently with the living organisms.

14-Appreciate the role of scientists in protecting living organisms from extinction.

1-Concept of extinction :

Extinction is the permanent end to the existence of a species. Through the vast expanse of geological time, extinction has been the fate of most kinds of living things on earth. The background rate of extinction has been more or less constant at about one species per million each year. New species arise at about the same rate. From time to time a mass extinction event occurs.

2-Using fossils to indicate extinction :

The fossils in rocks of different areas record indicate the extinction of spices of once living organisms most of them had been extincted before man.

3- Factors causing extinction of species:

1 -Destroying natural habitat

Like removing forests and destroy habitats of animals

2- Over hunting :

Hundreds of reptiles and mammals species become
recently extinct due to the absence of laws that control
wild animal hunting at the beginning of the 20th century.

The progressive development in the technology of
hunting weapons, and the increased rate of interest in
animal skins and furs

3 -Environmental pollution:

Since the industrial revolution in 1750, pollution has
propagated in all ecosystems. Among the ways of
pollution that contributed to the extinction of living
organisms are:

Acidic rain fall and destroy forest trees.
Chemical insecticides that break down the food chains.
Oil leaks in seas and oceans

4 Climatic changes and natural disasters :

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4-The extinct and endangered species :

First: Extinct species

A.Dodo bird :

it is not flying bird due to reduced size of its wings
cannot run fast due to its short legs. These features make it uneasy target for hunters (Fig. 13). It became extinct in 1681 in the Indian islands 50 years after Man invaded these islands.