[Biology Class Notes] on Extinction Pdf

What is Extinction?

Extinction is the elimination of species from the earth’s surface. It occurs when species disappear due to natural calamities or evolutionary changes of their relatives. 

It is recorded that the biggest extinction occurred some 250 million years ago, and is known as Great Dying. The event diminished almost 90% of the species on this planet. 

Extinct animals meaning suggests that no living member of that animal species exists anymore. IUCN has estimated that more than 26,500 species out of 96,500 are about to become extinct. It includes 40% of mammals and 25% of amphibians. Also, some scientists claim that it takes one million years for a species to become extinct. 

Fig: some extinct species

In the following section, we will discuss all the reasonable causes of extinction of wildlife.

Reasons Behind Extinction

There are several causes of extinction. However, it can be majorly divided into two parts, natural causes and human causes. 

1. Natural Causes Include the Following Factors.

  • Change in Climate- The changing climate of earth leads to the extinction of several species. The extreme weather condition, inadequate source of food forced many animals to die. 

  • Change in Sea Currents- The rise in the sea level and changing water currents severely reduces the lifespan of species that live close by. Consequently, marine sea creatures are the most vulnerable in this case.

  • Asteroids- Several mass extinctions occurred due to the lethal strikes of asteroids or meteors. For example, 66 million years ago, in the Cretaceous-Palaeogene age, the strike of a 93 miles wide meteor probably killed the dinosaurs.  

  • Disease- The sudden outbreak of pandemic and epidemic is one of the valid reasons for the extinction of a species. For example, the 1918 Spanish flu infected 500 million people, almost one-third of the world’s population, and killed about 100 million. 

  • Invasive Species- When a new species invades the spaces of any existing species of that region, they start to compete with each other. As a result, the fittest ones survive. 

  • Reduced Genetic Diversity- Sometimes because of less number of any species, the gene pool gets restricted. The extinct animal meaning indicates the same. Therefore, that species gradually proceeds towards extinction from that of being endangered. 

  • Lack of Adaptive Skills– The stronger species replaces the weaker one. Also, the species that cannot adapt to the changing surrounding or atmosphere goes extinct eventually. 

2. Human Causes Involve the Below-mentioned Factors. 

  • Pollution- Humans are a severe threat to several species. The rising pollution because of over usage of fossil fuels lead to the phenomenon like acid rains that kill many terrestrial organisms. Oil spills in oceans kill hundreds of aquatic creatures. Also, the recent treatment of plastic garbage entangles wildlife. For example, marine leatherback turtles are on the verge of becoming extinct because of plastic. 

  • Loss of Habitat- With the rapid rate of deforestation, the natural habitats of such regions had to migrate for shelter and food. It resulted in the extinction of some species. 

  • Overharvesting- People recklessly overharvest many species for medicines, food and other reasons. However, the resources are limited and it can lead to total extinction of numerous species. 

Now that you know the extinct animal’s meaning, check this list of examples of some of these. 

Extinct Animal Examples

A few examples of extinct animals are

Fill in The Blanks:

  1. Viable materials of endangered species can be preserved by _________________.

  2. A popular fruit, _____________ can become extinct because of a fungus attack. 

Answers: 1-Gene Banks, 2- Banana. 

To learn about extinct animal meaning and related topics in detail, access our study materials on the same. You can also download our app now for better access to online study sessions.

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