Extinction of plants and animals
03/10/2010 | WAYFARER | NS
Extinction is the end of a species of organism or group of organisms. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point).
Mass extinctions are when a very large number of species become extinct at around the same time, and are relatively rare events; however, isolated extinctions are quite common. The causes of mass extinctions include catastrophic events, e.g. meteorite impacts and comet showers, and earth agents e.g. volcanism, glaciation, variations in sea level, global climatic changes, and changes in ocean levels of oxygen or salinity. It is estimated most species that go extinct have never been documented by scientists. Some scientists estimate that up to half of presently existing species may become extinct by 2100.
Extinction is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct. Sadly, careless human activity on earth is increasingly contributing to extinctions and towards organisms becoming endangered.
Case study: The quagga
Above is a real photo of a quagga taken in Regent's Park Zoo, London in 1870. The case of the quagga's extinction is a classical example of deliberate and careless human activity leading to the extermination of an entire species.
For your term 4 research assignment, research and discuss the following questions:
1. How do humans endanger the survival of species?
2. What can humans do to protect endangered species or prevent extinctions?
3. When did the quagga become extinct?
4. What was the range of the quagga (where did it live)?
5. What were the main factors contributing to the quagga's extinction?
6. How do you feel that humans were responsible for an entire species dying out?
7. Discuss what is meant by the term "breeding back", and how does this relate to the quagga?
8. Mention any 10 modern extinct organisms, and briefly describe the context of each of these extinctions.
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