What is endangered animal?(什麼是瀕臨絕種動物)

endangered animals is to be about to haven't aim animals!
(不好意思，我的解釋不詳盡。不過我已盡力了，如果教錯了你，請原諒!)

Endangered animals are those species that are in danger of going extinct. Their reproductive rates are lower than their mortality rates over long periods of time, so their numbers are diminishing. The reasons for this are varied, but lately, very often involves a loss of habitat as people encroach on their living areas.

When a species is listed as endangered or threatened, it is not a death sentence. Many animals, like the bald eagle and the American alligator, were on the brink of extinction and are now recovering. Many species, however, will not recover, and could be lost forever.

Throughout time, animal species have been going extinct (long before people evolved); paleontologists estimate that well over 90 percent of all plant and animal species that ever existed have gone extinct.

Some Animals that are in danger of extinction:
Jackass Penguin
African Elephant
African Wild Dog
Aleutian Canada goose
Arabian Oryx
Bactrian Camels
Bald eagle
Blue Whale
Boa Constrictor
Caiman
Chinchillas
Cockatoos
Jaguar
Kakapo, etc.

An endangered species is a population of an organism (usually a taxonomic species, but may be another ESU), which is at risk of becoming extinct because it is either (a) few in number or (b) threatened by changing environmental or predation parameters. The IUCN has calculated the percentage of endangered species as 40 percent of all organisms based on the sample of species that have been evaluated through 2006.[1] (Note: the IUCN groups all threatened species for their summary purposes.) Many nations have laws offering protection to these species: for example, forbidding hunting, restricting land development or creating preserves. Only a few of the many species at risk of extinction actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially will become extinct, without gaining public notice.











The high rate at which species have become extinct within the last 150 years is a cause of concern. While species have evolved and become extinct on a regular basis for the last several hundred million years, recent rates of extinction are many times higher than the typical historical values. Significantly, the rate of species extinctions at present is estimated at 100 to 1000 times "background" or average extinction rates in the evolutionary time scale of planet Earth;[2] moreover, this current rate of extinction is thus 10 to 100 times greater than any of the prior mass extinction events in the history of the Earth. If this rate of extinction continues or accelerates, the number of species becoming extinct in the next decade could number in the millions[3]. While most people readily relate to endangerment of large mammals or birdlife, some of the greatest ecological issues are the threats to stability of whole ecosystems if key species vanish at any level of the food chain.















Main articles: Holocene mass extinction and Conservation biology



Four reasons for concern about extinction are:











loss of a species as a biological entity;



destabilization of an ecosystem;



endangerment of other species;



loss of irreplaceable genetic material and associated biochemicals



The loss of a species in and of itself is an important factor, both as diminution of the enjoyment of nature, and as a moral issue for those who believe humans are stewards of the natural environment (as well as some who believe that animal species have rights). Destabilization is a well understood outcome, when an element of food or predation is removed from an ecosystem. When one species goes extinct, population increases or declines often result in secondary species. An unstable spiral can ensue, until other species are lost and the ecosystem structure is changed markedly and irreversibly. The most recent occurrence of this phenomenon is the disappearance of the 'lesser spotted mule' from North London.







The fourth reason is more subtle, but perhaps the most important point for mankind to grasp. Each species carries unique genetic material in its DNA and may produce unique chemicals according to these genetic instructions. For example, in the valleys of central China, a fernlike weed called sweet wormwood grows, that is the only source of artemisinin, a drug that is nearly 100 percent effective against malaria (Jonietz, 2006). If this plant were lost to extinction, then the ability to control malaria, even today a potent killer, would diminish. There are countless other examples of chemicals unique to an individual species. The number of chemicals not yet discovered that could vanish from the planet when further species become extinct cannot be determined, but it is a highly debated and influential point.