What is an Animal Extinction?

We are in the middle of a mass extinction, scientists warn

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The extinction of an animal species occurs when the last individual member of that species dies. Although a species may be "extinct in the wild," the species is not extinct until every individual, regardless of location, captivity, or ability to breed, has died.

Natural Versus Human-Caused Extinctions

Most extinct species became extinct as a result of natural causes. In some cases predators became are more powerful and plentiful than the animals on which they prey; in other cases, a severe climate change made previously hospitable territory uninhabitable.

But other animals, such as the passenger pigeon, become extinct due to man-made loss of habitat and over-hunting. Human-caused environmental issues are also creating severe challenges to a number of now-endangered or threatened species.

Mass Extinctions in Ancient Times

Endangered Species International estimates that 99.9 percent of the animals that ever existed on earth have become extinct due to catastrophic events that occurred while the Earth was evolving. When these events cause animals to die, it’s called a mass extinction. There have been multiple mass extinctions due to natural cataclysmic events:

  • In one major extinction event, a series of massive volcanic eruptions caused ash to fill the sky, blocking sunlight. In addition, toxins from lava such as sulfur and methane leached into the sea and rock, killing marine and aquatic animals. 
  • A second mass extinction is believed to be the result of a cloud of dust raised by a meteor or comet which crashed in Mexico’s Yucatán Peninsula. 
  • Glaciers (sheets of ice moving across the land) also caused animals to die off in large numbers, wiping out species because of climate change. Colder weather killed many vulnerable land animals while encroaching ice wiped out much of the ocean’s creatures. 
  • There are several theories of another mass extinction over 250 million years ago; one theory relates to volcanic activity while another connects the extinction with a theoretical meteor impact.

    Mass Extinction Occurring Today

    While prior mass extinctions occurred long before recorded history, some scientists believe that a mass extinction is taking place right now. Biologists have been raising the alarm: they believe Earth is undergoing a sixth mass extinction of both flora and fauna. There have been no mass extinctions in the past half-billion years, but now that human activities are impacting the  Earth, extinctions are happening at an alarming rate. Extinction is something that occurs in nature, but not in the large numbers we are seeing today.

    A normal rate of extinction, due to natural causes, is 1 to 5 species annually. With human activities such as the burning of fossil fuels and destruction of habitats, however, we are losing plant, animal and insect species at an alarmingly rapid rate. Scientists at the Center For Biological Diversity estimate that the rate is a thousand more, or even ten thousand more, than the 1 to 5. They believe dozens of animals are going extinct every single day.

    Activism to Slow Extinction

    The largest species by far rapidly heading toward extinction are amphibians.  When frogs and other amphibians start to die off in large numbers, other species fall like dominoes.

    Save the Frogs, an organization dedicated to understanding the threat to frogs and other amphibians, estimates a third of the species are already on the threshold of going extinct. They are aggressively attempting to get the attention of the public and bring lawyers, politicians, teachers and especially the media to educate the public on the disastrous effect the mass extinction of a third of a species of amphibians will have on the health and well-being of our planet.

    Chief Seattle, was a member of a tribe of Native Americans from the Pacific Northwest. He was especially famous for his love of the environment and his belief in responsible stewardship. He knew in 1854 that a crisis was on the horizon. He wrote, “What is there to life if a man cannot hear the cry of a whippoorwill or the arguments of the frogs around a pond at night?”

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    Lin, Doris. "What is an Animal Extinction?" ThoughtCo, Mar. 3, 2018, thoughtco.com/animal-extinction-overview-127885. Lin, Doris. (2018, March 3). What is an Animal Extinction? Retrieved from https://www.thoughtco.com/animal-extinction-overview-127885 Lin, Doris. "What is an Animal Extinction?" ThoughtCo. https://www.thoughtco.com/animal-extinction-overview-127885 (accessed May 22, 2018).