The african elephant is classified as a member of the order Proboscidea (Elephants) and is a member of the family Elephantidae. The male stands up to ten feet high to its shoulder, and weighs up to six tons. The female is slightly smaller, and weighs up to four tons. It is classified as an endangered species due to a reduction of at least 50% of the african elephant population over the last three generations based on an index of abundance. Hunting of the african elephant is now banned in several countries, but poaching for ivory still exists.

The asian elephant is classified as a member of the order Proboscidea (Elephants) and is a member of the family Elephantidae. It stands up to ten feet high and twenty feet long. It weighs up to 10,000 pounds. The asian elephant is classified as an endangered species due to a reduction of at least 50% of the asian elephant population over the last three generations based on an index of abundance and a decline in area of occupancy. The Asian elephant has four subspecies: the Indian, Ceylon, Sumatran, and Malaysian elephants.

The gorilla is classified as a member of the order Primates and is a member of the family Hominidae. The male gorilla grows to about six feet high, and weighs up to six hundred pounds. The female gorilla grows to about five feet high, and weighs up to two hundred pounds. The gorilla is classified as an endangered species due to the projected gorilla population declining to at the highest 50% due to a decline in area of occupancy. The gorilla is the largest and most powerful primate alive, but is a peaceful and sociable animal.

- Hybrid Spider Monkey (Ateles belzebuth hybridus)

The hybrid spider monkey is classified as a member of the order Primates and is a member of the family Cebidae. The hybrid spider monkey grows to almost two feet long, not including the tail. It weighs from ten to fifteen pounds. The hybrid spider monkey is classified as an endangered species due to the fact that it only exists in severely fragmented subpopulations, and that there has been continuing decline in the hybrid spider monkey population. The hybrid spider monkey is known for its ability to use its tail as an extra limb.

- Aye-aye (Daubentonia madagascariensis)

-  Tiger (Panthera tigris)

The red wolf is classified as a member of the order Carnivora (Carnivores) and is a member of the family Canidae. The red wolf is classified as a critically endangered species due to the estmation that its population consists of less than fifty mature red wolves.

The amur leopard is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is classified as a critically endangered species due to a reduction of at least 80% of its population over the past three generations because of a decline in area of occupancy, extent of occurance, or quality of habitat. The amur leopard population is also estimated to be less than 50 mature individuals. Amur leopards can be found in eastern Asia.

The anatolian leopard is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is classified as a critically endangered species due to an estimated population of less than 250 mature individuals and a continuing decline in numbers of mature individuals and population structure in the form of severely fragmented populations. Anatolian leopards can be found in Turkey.

The Asiatic cheetah is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is classified as a critically endangered species due to an estimated population of less than 50 mature individuals and a continuing decline in numbers of mature individuals and population structure due to the fact that all Asiatic cheetahs are in a single population. Asiatic cheetahs can be found in Iran.

The Florida cougar is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is also known as the Florida panther and the Florida Puma. It is classified as a critically endangered species due to an estimated population of less than 50 mature individuals. Florida cougars can be found in the United States.

The iberian lynx is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is classified as an endangered species due to an estimated population of less than 2500 mature individuals and an extimated continuing decline of at least 20% of its population within two generations. Iberian lynx can be found in Portugal and Spain.

The Texas ocelot is classified as a member of the order Carnivora (Carnivores) and is a member of the family Felidae. It is classified as an endangered species due to an estimated population of less than 250 mature individuals. The Texas ocelot can be found in Mexico and the United States.

The marine otter is classified as a member of the order Carnivora (Carnivores) and is a member of the family Mustelidae. It is classified as an endangered species due to the marine otter population declining because of the levels of exploitation and a decline in its area of occupancy. Marine otters can be found in South America.

The giant panda is classified as a member of the order Carnivora (Carnivores) and is a member of the family Procyonidae. The male giant panda stands up to five feet tall, and weighs up to 265 pounds. The female giant panda is smaller and weighs less. The giant panda is classified as an endangered species due to the fact that it only exists in severely fragmented subpopulations consisting of up to 250 mature adults, and that there has been continuing decline in the area of habitat. The giant panda feeds mainly on bamboo, even though it is classified as a carnivore.

The Broom's Pygmy-possum is classified as a member of the order Marsupialia (Marsupials) and is a member of the family Burramyidae. It is also known as the mountain pygmy-possum. The Broom's pygmy-possum is classified as an endangered species due to an estimated extent of occurrence that is less than 5000 km², a severely fragmented population, and a projected decline in area of occupancy, extent of occurance, quality of habitat, number of subpopulations, and number of mature individuals. The Broom's pygmy-possum can be found in Australia.

The northern hairy-nosed wombat is classified as a member of the order Marsupialia (Marsupials) and is a member of the family Vombatidae. It is classified as a critically endangered species due to an estimated extent of occurrence that is less than 100 km², a severely fragmented population, a projected decline in quality of habitat, and an estimated population of less than 50 mature individuals. The northern hairy-nosed wombat can be found in Australia.

The short-tailed chinchilla is classified as a member of the order Rodentia (Rodents) and is a member of the family Chinchillidae. It is classified as a critically endangered species due to an estimated population decline of at least 80% over the past ten years based on a decline in area of occupancy and levels of exploitation. The short-tailed chinchilla can be found in South America.

The giant armadillo is classified as a member of the order Edentata (Edentates) and is a member of the family Dasypodidae. It is classified as an endangered species due to an estimated population decline of at least 50% over the past ten years based on a decline in area of occupancy and levels of exploitation. The giant armadillo can be found in South America. 

The California condor is classified as a member of the order Falconiformes (Eagles, hawks, and vultures) and is a member of the family Cathartidae. It is classified as aa critically endangered species due to an estimated population of less than 50 mature individuals. The California condor can be found in the United States.

The Mauritius kestrel is classified as a member of the order Falconiformes (Eagles, hawks, and vultures) and is a member of the family Falconidae. The Mauritius kestrel is classified as an endangered species due to an estimated population of less than 250 mature Mauritius kestrels.

The marquesan kingfisher is classified as a member of the order Coraciiformes (Kingfishers, hornbills, and allies) and is a member of the family Alcedinidae. It is classified as an endangered species due to a severely fragmented population and a projected decline of mature marquesan kingfishers.

The rufous-lored kingfisher is classified as a member of the order Coraciiformes (Kingfishers, hornbills, and allies) and is a member of the family Alcedinidae. The rufous-lored kingfisher is classified as an endangered species due to a reduction of at least 50% of the rufous-lored kingfisher population over the last three generations based on a decline in area of occupancy, and a projected decline of at least 50% over the next three generations based on the same reason.

The Hawaiian crow is classified as a member of the order Passeriformes (Passerines) and is a member of the family Corvidae. The Hawaiian crow is classified as a critically endangered species due to an estimated population of less than 50 mature Hawaiian crows.

The cochabamba mountain-finch is classified as a member of the order Passeriformes (Passerines) and is a member of the family Emberizidae. The cochabamba mountain-finch is classified as an endangered species due to the existence of only a single population numbering no more than 2500 mature adults, a decline in area of habitat, and an estimated decline of at least 20% over the next ten years.

The gouldian finch is classified as a member of the order Passeriformes (Passerines) and is a member of the family Estrildidae. The gouldian finch is classified as an endangered species due to the fact that it only exists in severely fragmented subpopulations, and that a continuing decline is projected in the number of subpopulations and the number of mature adults.

The blue-bellied parrot is classified as a member of the order Psittaciformes (Parrots) and is a member of the family Psittacidae. The blue-bellied parrot is classified as an endangered species due to the fact that it only exists in severely fragmented subpopulations of no more than 250 mature parrots each.

The whooping crane is classified as a member of the order Gruiformes (Cranes, rails, trumpeters) and is a member of the family Gruidae. It is classified as an endangered species due to an estimated population of less than 250 mature cranes. The whooping crane can be found in Canada and the United States.

The crested shelduck is classified as a member of the order Anseriformes (Screamers and ducks) and is a member of the family Anatidae. It is classified as a critically endangered species due to an estimated population of less than 50 mature crested shelducks. The species can be found in eastern Asia.

The white-winged duck is classified as a member of the order Anseriformes (Screamers and ducks) and is a member of the family Anatidae. It is classified as an endangered species due to an estimated population of less than 2500 mature white-winged ducks, an estimated continuing decline of the population, and a severely fragmented population. The white-winged duck can be found in southern Asia.

The Siberian sturgeon is classified as a member of the order Acipenseriformes and is a member of the family Acipenseridae. It is classified as an endangered species due to a projected reduction of at least 50% of the Siberian sturgeon population over the next ten years based on actual levels of exploitation.

The Alabama sturgeon is classified as a member of the order Acipenseriformes and is a member of the family Acipenseridae. It is classified as a critically endangered species due to a reduction of at least 80% of the Alabama sturgeon population over the last ten years based on a decline in area of occupancy and actual levels of exploitation, and a projected decline of at least 80% over the next ten years based on the same reason.

The Chinese paddlefish is classified as a member of the order Acipenseriformes and is a member of the family Polyodontidae. It is classified as a critically endangered species due to a projected reduction of at least 80% of the Alabama sturgeon population over the next ten years based on a decline in area of occupancy and actual levels of exploitation.

The Alabama shad is classified as a member of the order Clupeiformes (Herrings) and is a member of the family Clupeidae. It is classified as an endangered species due to a severely fragmented population and a continuing decline in the number of mature adults.

The silver shark is classified as a member of the order Cypriniformes and is a member of the family Cyprinidae. The silver shark is classified as an endangered species due to a reduction of at least e0% of the silver shark population over the last ten years based on direct observation and a decline in area of occupancy.

The clanwilliam redfin is classified as a member of the order Cypriniformes and is a member of the family Cyprinidae. The clanwilliam redfin is classified as an endangered species due to the fact that its estimated area of occurence is less than 5000 km², it is known to exist at no more than five locations, and continuing decline is projected for extent of occurence and area of habitat.

The wild common carp is classified as a member of the order Cypriniformes and is a member of the family Cyprinidae. It is classified as a critically endangered species due to a projected reduction of at least 80% of the wild common carp population over the next ten years based on a decline in area of occupancy and introduced pollutants, parasites, or other threats.

Our planet is continually changing, causing habitats to be altered and modified. Natural changes tend to occur at a gradual pace, usually causing only a slight impact on individual species. However, when changes occur at a fast pace, there is little or no time for individual species to react and adjust to new circumstances. This can create disastrous results, and for this reason, rapid habitat loss is the primary cause of species endangerment. The strongest forces in rapid habitat loss are human beings. Nearly every region of the earth has been affected by human activity, particularly during this past century. The loss of microbes in soils that formerly supported tropical forests, the extinction of fish and various aquatic species in polluted habitats, and changes in global climate brought about by the release of greenhouse gases are all results of human activity.

It can be difficult for an individual to recognize the effects that humans have had on specific species. It is hard to identify or predict human effects on individual species and habitats, especially during a human lifetime. But it is quite apparent that human activity has greatly contributed to species endangerment. For example, although tropical forests may look as though they are lush, they are actually highly susceptible to destruction. This is because the soils in which they grow are lacking in nutrients. It may take Centuries to re-grow a forest that was cut down by humans or destroyed by fire, and many of the world's severely threatened animals and plants live in these forests. If the current rate of forest loss continues, huge quantities of plant and animal species will disappear.

Native species are those plants and animals that are part of a specific geographic area, and have ordinarily been a part of that particular biological landscape for a lengthy period of time. They are well adapted to their local environment and are accustomed to the presence of other native species within the same general habitat. Exotic species, however, are interlopers. These species are introduced into new environments by way of human activities, either intentionally or accidentally. These interlopers are viewed by the native species as foreign elements. They may cause no obvious problems and may eventual be considered as natural as any native species in the habitat. However, exotic species may also seriously disrupt delicate ecological balances and may produce a plethora of unintended yet harmful consequences.

The worst of these unintended yet harmful consequences arise when introduced exotic species put native species in jeopardy by preying on them. This can alter the natural habitat and can cause a greater competition for food. Species have been biologically introduced to environments all over the world, and the most destructive effects have occurred on islands. Introduced insects, rats, pigs, cats, and other foreign species have actually caused the endangerment and extinction of hundreds of species during the past five centuries. Exotic species are certainly a factor leading to endangerment.

A species that faces overexploitation is one that may become severely endangered or even extinct due to the rate in which the species is being used. Unrestricted whaling during the 20th century is an example of overexploitation, and the whaling industry brought many species of whales to extremely low population sizes. When several whale species were nearly extinct, a number of nations (including the United States) agreed to abide by an international moratorium on whaling. Due to this moratorium, some whale species, such as the grey whale, have made remarkable comebacks, while others remain threatened or endangered.

Due to the trade in animal parts, many species continue to suffer high rates of exploitation. Even today, there are demands for items such as rhino horns and tiger bones in several areas of Asia. It is here that there exists a strong market for traditional medicines made from these animal parts.

Disease, pollution, and limited distribution are more factors that threaten various plant and animal species. If a species does not have the natural genetic protection against particular pathogens, an introduced disease can have severe effects on that specie. For example, rabies and canine distemper viruses are presently destroying carnivore populations in East Africa. Domestic animals often transmit the diseases that affect wild populations, demonstrating again how human activities lie at the root of most causes of endangerment. Pollution has seriously affected multiple terrestrial and aquatic species, and limited distributions are frequently a consequence of other threats; populations confined to few small areas due to of habitat loss, for example, may be disastrously affected by random factors.