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.
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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
Sabre-toothed cats
Woolly mammoth
Large sloth lemur
Labrador duck
Steller's sea cow
Tasmanian tiger
Quagga
Pyrenean Ibex
Baji white dolphin
West African black rhinos
Fill in The Blanks:
Viable materials of endangered species can be preserved by _________________.
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 Vedantu app now for better access to online study sessions.
FAQs on Extinction
1. What is extinction in the context of biology?
In biology, extinction refers to the complete termination or disappearance of a species or a group of organisms from Earth. This means that there are no living individuals of that species left anywhere in the world. While extinction is a natural part of the evolutionary process, the current rate of species loss is significantly accelerated due to human activities.
2. What are the main types of extinction events?
Extinction events are primarily categorised into two main types based on their scale and cause:
- Background Extinction: This refers to the standard, continuous low rate of extinction that occurs over long periods as a natural part of evolution. Species may disappear due to competition, climate change, or evolving into new species.
- Mass Extinction: This is a widespread and rapid decrease in the biodiversity on Earth, where a significant percentage of all species across different phyla are wiped out in a geologically short period. These are often caused by catastrophic events like massive volcanic eruptions or asteroid impacts.
- Co-extinction: This happens when the extinction of one species causes the extinction of another, often in cases of obligatory relationships like a parasite and its host or a plant and its specific pollinator.
3. What are the primary causes of species extinction as per the CBSE syllabus?
The main anthropogenic (human-induced) causes of species extinction are collectively known as 'The Evil Quartet'. These four major causes are:
- Habitat Loss and Fragmentation: This is the most significant cause. It occurs when natural habitats like forests or wetlands are destroyed or broken into small, isolated patches, making it impossible for species to survive and reproduce.
- Over-exploitation: This involves harvesting a species from the wild at a rate that is unsustainable, leading to its decline and eventual extinction. Over-hunting and over-fishing are common examples, such as the case of the Steller's sea cow and passenger pigeon.
- Alien Species Invasions: When non-native species are introduced into an ecosystem (either intentionally or accidentally), they can out-compete native species for resources, introduce diseases, or become predators, leading to the extinction of indigenous organisms. The introduction of the Nile perch into Lake Victoria is a key example.
- Co-extinctions: As mentioned, when one species becomes extinct, plant and animal species associated with it in an obligatory way also face extinction.
4. How does a mass extinction differ from the normal background rate of extinction?
The primary difference lies in the rate and scale. Background extinction is a slow, steady, and ongoing process with a relatively low number of species disappearing over time. In contrast, a mass extinction is a catastrophic event where more than 75% of all species on Earth disappear in a geologically short period (a few million years or less). Scientists believe we are currently in a sixth mass extinction, driven primarily by human activity, with extinction rates estimated to be 100 to 1,000 times higher than the natural background rate.
5. What is the difference between an 'extinct' species and an 'endangered' species?
The difference is based on the survival status of the species. An extinct species, like the Dodo or Thylacine, has no living individuals remaining anywhere on the planet. An endangered species is one that is at a very high risk of becoming extinct in the near future. Organisations like the IUCN use a 'Red List' to categorise species based on their risk level, including categories like 'Critically Endangered', 'Endangered', and 'Vulnerable', to guide conservation efforts.
6. Why is the loss of a 'keystone species' particularly damaging for an ecosystem?
A keystone species is an organism that has a disproportionately large effect on its natural environment relative to its abundance. Its removal can trigger a 'trophic cascade,' which is a chain reaction of extinctions and disruptions throughout the ecosystem's food web. For example, the removal of sea otters (a keystone predator) can lead to an explosion in the sea urchin population, which then overgrazes and destroys kelp forests, leading to the loss of habitat for numerous other species. Therefore, the extinction of a keystone species can cause the entire ecosystem structure to collapse.
7. Can you give some examples of recently extinct animals and the reasons for their disappearance?
Certainly. Several well-documented recent extinctions highlight the impact of human activities:
- The Dodo (Mauritius): This flightless bird became extinct in the late 17th century due to hunting by sailors and predation by invasive species they introduced, like pigs and rats.
- The Quagga (Africa): A subspecies of the plains zebra, it was hunted to extinction for its meat and hide in the late 19th century.
- The Thylacine (Australia/Tasmania): Also known as the Tasmanian tiger, this carnivorous marsupial was hunted to extinction due to bounties and perceived threats to livestock, with the last known individual dying in 1936.
- Steller's Sea Cow (Russia): This large, slow-moving marine mammal was discovered in 1741 and hunted to extinction for its meat, fat, and hide within just 27 years of its discovery.
