An endangered species is a type of organism that is threatened by extinction. Species become endangered for two main reasons: loss of habitat and loss of genetic variation.
Loss of Habitat
A loss of habitat can happen naturally. Dinosaurs, for instance, lost their habitat about 65 million years ago. The hot, dry climate of the Cretaceous period changed very quickly, most likely because of an asteroid striking the Earth. The impact of the asteroid forced debris into the atmosphere, reducing the amount of heat and light that reached Earth’s surface. The dinosaurs were unable to adapt to this new, cooler habitat. Dinosaurs became endangered, then extinct.
Human activity can also contribute to a loss of habitat. Development for housing, industry, and agriculture reduces the habitat of native organisms. This can happen in a number of different ways.
Development can eliminate habitat and native species directly. In the Amazon rain forest of South America, developers have cleared hundreds of thousands of acres. To “clear” a piece of land is to remove all trees and vegetation from it. The Amazon rain forest is cleared for cattle ranches, logging, and urban use.
Development can also endanger species indirectly. Some species, such as fig trees of the rain forest, may provide habitat for other species. As trees are destroyed, species that depend on that tree habitat may also become endangered. Tree crowns provide habitat in the canopy, or top layer, of a rainforest. Plants such as vines, fungi such as mushrooms, and insects such as butterflies live in the rain forest canopy. So do hundreds of species of tropical birds and mammals such as monkeys. As trees are cut down, this habitat is lost. Species have less room to live and reproduce.
Loss of habitat may happen as development takes place in a species range. Many animals have a range of hundreds of square kilometers. The mountain lion of North America, for instance, has a range of up to 1,000 square kilometers (386 square miles). To successfully live and reproduce, a single mountain lion patrols this much territory. Urban areas, such as Los Angeles, California, and Vancouver, British Columbia, Canada, grew rapidly during the 20th century. As these areas expanded into the wilderness, the mountain lion’s habitat became smaller. That means the habitat can support fewer mountain lions. Because enormous parts of the Sierra Nevada, Rocky, and Cascade mountain ranges remain undeveloped, however, mountain lions are not endangered.
Loss of habitat can also lead to increased encounters between wild species and people. As development brings people deeper into a species range, they may have more exposure to wild species. Poisonous plants and fungi may grow closer to homes and schools. Wild animals are also spotted more frequently. These animals are simply patrolling their range, but interaction with people can be deadly. Polar bears, mountain lions, and alligators are all predators brought into close contact with people as they lose their habitat to homes, farms, and businesses. As people kill these wild animals, through pesticides, accidents such as collisions with cars, or hunting, native species may become endangered.
Loss of Genetic Variation
Genetic variation is the diversity found within a species. It’s why human beings may have blond, red, brown, or black hair. Genetic variation allows species to adapt to changes in the environment. Usually, the greater the population of a species, the greater its genetic variation.
Inbreeding is reproduction with close family members. Groups of species that have a tendency to inbreed usually have little genetic variation, because no new genetic information is introduced to the group. Disease is much more common, and much more deadly, among inbred groups. Inbred species do not have the genetic variation to develop resistance to the disease. For this reason, fewer offspring of inbred groups survive to maturity.
Loss of genetic variation can occur naturally. Cheetahs are a threatened species native to Africa and Asia. These big cats have very little genetic variation. Biologists say that during the last ice age, cheetahs went through a long period of inbreeding. As a result, there are very few genetic differences between cheetahs. They cannot adapt to changes in the environment as quickly as other animals, and fewer cheetahs survive to maturity. Cheetahs are also much more difficult to breed in captivity than other big cats, such as lions.
Human activity can also lead to a loss of genetic variation. Overhunting and overfishing have reduced the populations of many animals. Reduced population means there are fewer breeding pairs. A breeding pair is made up of two mature members of the species that are not closely related and can produce healthy offspring. With fewer breeding pairs, genetic variation shrinks.
Monoculture, the agricultural method of growing a single crop, can also reduce genetic variation. Modern agribusiness relies on monocultures. Almost all potatoes cultivated, sold, and consumed, for instance, are from a single species, the Russet Burbank. Potatoes, native to the Andes Mountains of South America, have dozens of natural varieties. The genetic variation of wild potatoes allows them to adapt to climate change and disease. For Russet Burbanks, however, farmers must use fertilizers and pesticides to ensure healthy crops because the plant has almost no genetic variation.
Plant breeders often go back to wild varieties to collect genes that will help cultivated plants resist pests and drought, and adapt to climate change. However, climate change is also threatening wild varieties. That means domesticated plants may lose an important source of traits that help them overcome new threats.
The Red List
The International Union for Conservation of Nature (IUCN) keeps a “Red List of Threatened Species.” The Red List defines the severity and specific causes of a species’ threat of extinction. The Red List has seven levels of conservation: least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild, and extinct. Each category represents a different threat level.
Species that are not threatened by extinction are placed within the first two categories—least concern and near-threatened. Those that are most threatened are placed within the next three categories, known as the threatened categories—vulnerable, endangered, and critically endangered. Those species that are extinct in some form are placed within the last two categories—extinct in the wild and extinct.
Classifying a species as endangered has to do with its range and habitat, as well as its actual population. For this reason, a species can be of least concern in one area and endangered in another. The gray whale, for instance, has a healthy population in the eastern Pacific Ocean, along the coast of North and South America. The population in the western Pacific, however, is critically endangered.
Least concern is the lowest level of conservation. A species of least concern is one that has a widespread and abundant population. Human beings are a species of least concern, along with most domestic animals, such as dogs and cats. Many wild animals, such as pigeons and houseflies, are also classified as least concern.
A near threatened species is one that is likely to qualify for a threatened category in the near future.
Many species of violets, native to tropical jungles in South America and Africa, are near threatened, for instance. They have healthy populations, but their rain forest habitat is disappearing at a fast pace. People are cutting down huge areas of rain forest for development and timber. Many violet species are likely to become threatened.
The definitions of the three threatened categories (vulnerable, endangered, and critically endangered) are based on five criteria: population reduction rate, geographic range, population size, population restrictions, and probability of extinction.
Threatened categories have different thresholds for these criteria. As the population and range of the species decreases, the species becomes more threatened.
1) Population reduction rate
A species is classified as vulnerable if its population has declined between 30 and 50 percent. This decline is measured over 10 years or three generations of the species, whichever is longer. A generation is the period of time between the birth of an animal and the time it is able to reproduce. Mice are able to reproduce when they are about one month old. Mouse populations are mostly tracked over 10-year periods. An elephant's generation lasts about 15 years. So, elephant populations are measured over 45-year periods.
A species is vulnerable if its population has declined at least 50 percent and the cause of the decline is known. Habitat loss is the leading known cause of population decline.
A species is also classified as vulnerable if its population has declined at least 30 percent and the cause of the decline is not known. A new, unknown virus, for example, could kill hundreds or even thousands of individuals before being identified.
2) Geographic range
A species is vulnerable if its “extent of occurrence” is estimated to be less than 20,000 square kilometers (7,722 square miles). An extent of occurrence is the smallest area that could contain all sites of a species’ population. If all members of a species could survive in a single area, the size of that area is the species’ extent of occurrence.
A species is also classified as vulnerable if its “area of occupancy” is estimated to be less than 2,000 square kilometers (772 square miles). An area of occupancy is where a specific population of that species resides. This area is often a breeding or nesting site in a species range.
3) Population size
Species with fewer than 10,000 mature individuals are vulnerable. The species is also vulnerable if that population declines by at least 10 percent within 10 years or three generations, whichever is longer.
4) Population restrictions
Population restriction is a combination of population and area of occupancy. A species is vulnerable if it is restricted to less than 1,000 mature individuals or an area of occupancy of less than 20 square kilometers (8 square miles).
5) Probability of extinction in the wild is at least 10 percent within 100 years.
Biologists, anthropologists, meteorologists, and other scientists have developed complex ways to determine a species’ probability of extinction. These formulas calculate the chances a species can survive, without human protection, in the wild.
Vulnerable Species: Ethiopian Banana Frog
The Ethiopian banana frog (Afrixalus enseticola) is a small frog native to high-altitude areas of southern Ethiopia. It is a vulnerable species because its area of occupancy is less than 2,000 square kilometers (772 square miles). The extent and quality of its forest habitat are in decline. Threats to this habitat include forest clearance, mostly for housing and agriculture.
Vulnerable Species: Snaggletooth Shark
The snaggletooth shark (Hemipristis elongatus) is found in the tropical, coastal waters of the Indian and Pacific Oceans. Its area of occupancy is enormous, from southeast Africa to the Philippines, and from China to Australia.
However, the snaggletooth shark is a vulnerable species because of a severe population reduction rate. Its population has fallen more than 10 percent over 10 years. The number of sharks is declining due to fisheries, especially in the Java Sea and Gulf of Thailand. The snaggletooth shark’s flesh, fins, and liver are considered high-quality foods. They are sold in commercial fish markets, as well as restaurants.
Vulnerable Species: Galapagos Kelp
Galapagos kelp (Eisenia galapagensis) is a type of seaweed only found near the Galapagos Islands in the Pacific Ocean. Galapagos kelp is classified as vulnerable because its population has declined more than 10 percent over 10 years.
Climate change is the leading cause of decline among Galapagos kelp. El Nino, the natural weather pattern that brings unusually warm water to the Galapagos, is the leading agent of climate change in this area. Galapagos kelp is a cold-water species and does not adapt quickly to changes in water temperature.
1) Population reduction rate
A species is classified as endangered when its population has declined between 50 and 70 percent. This decline is measured over 10 years or three generations of the species, whichever is longer.
A species is classified as endangered when its population has declined at least 70 percent and the cause of the decline is known. A species is also classified as endangered when its population has declined at least 50 percent and the cause of the decline is not known.
2) Geographic range
An endangered species’ extent of occurrence is less than 5,000 square kilometers (1,930 square miles). An endangered species’ area of occupancy is less than 500 square kilometers (193 square miles).
3) Population size
A species is classified as endangered when there are fewer than 2,500 mature individuals. When a species population declines by at least 20 percent within five years or two generations, it is also classified as endangered.
4) Population restrictions
A species is classified as endangered when its population is restricted to less than 250 mature individuals. When a species’ population is this low, its area of occupancy is not considered.
5) Probability of extinction in the wild is at least 20 percent within 20 years or five generations, whichever is longer.
Endangered Species: Siberian Sturgeon
The Siberian sturgeon (Acipenser baerii) is a large fish found in rivers and lakes throughout the Siberian region of Russia. The Siberian sturgeon is a benthic species. Benthic species live at the bottom of a body of water.
The Siberian sturgeon is an endangered species because its total population has declined between 50 and 80 percent during the past 60 years (three generations of sturgeon). Overfishing, poaching, and dam construction have caused this decline. Pollution from mining activities has also contributed to abnormalities in the sturgeon’s reproductive system.
Endangered Species: Tahiti Reed-warbler
The Tahiti reed-warbler (Acrocephalus caffer) is a songbird found on the Pacific island of Tahiti. It is an endangered species because it has a very small population. The bird is only found on a single island, meaning both its extent of occurrence and area of occupancy are very small.
The Tahiti reed-warbler is also endangered because of human activity. The tropical weed Miconia is a non-native species that has taken over much of Tahiti’s native vegetation. The reed-warbler lives almost exclusively in Tahiti’s bamboo forests. The bird nests in bamboo and feeds on flowers and insects that live there. As development and invasive species such as Miconia destroy the bamboo forests, the population of Tahiti reed-warblers continues to shrink.
Endangered Species: Ebony
Ebony (Diospyros crassiflora) is a tree native to the rain forests of central Africa, including Congo, Cameroon, and Gabon. Ebony is an endangered species because many biologists calculate its probability of extinction in the wild is at least 20 percent within five generations.
Ebony is threatened due to overharvesting. Ebony trees produce a very heavy, dark wood. When polished, ebony can be mistaken for black marble or other stone. For centuries, ebony trees have been harvested for furniture and sculptural uses such as chess pieces. Most ebony, however, is harvested to make musical instruments such as piano keys and the fingerboards of stringed instruments.
Critically Endangered Species
1) Population reduction rate
A critically endangered species’ population has declined between 80 and 90 percent. This decline is measured over 10 years or three generations of the species, whichever is longer.
A species is classified as critically endangered when its population has declined at least 90 percent and the cause of the decline is known. A species is also classified as endangered when its population has declined at least 80 percent and the cause of the decline is not known.
2) Geographic range
A critically endangered species’ extent of occurrence is less than 100 square kilometers (39 square miles). A critically endangered species’ area of occupancy is estimated to be less than 10 square kilometers (4 square miles).
3) Population size
A species is classified as critically endangered when there are fewer than 250 mature individuals. A species is also classified as critically endangered when the number of mature individuals declines by at least 25 percent within three years or one generation, whichever is longer.
4) Population restrictions
A species is classified as critically endangered when its population is restricted to less than 50 mature individuals. When a species’ population is this low, its area of occupancy is not considered.
5) Probability of extinction in the wild is at least 50 percent within 10 years or three generations, whichever is longer.
Critically Endangered Species: Bolivian Chinchilla Rat
The Bolivian chinchilla rat (Abrocoma boliviensis) is a rodent found in a small section of the Santa Cruz region of Bolivia. It is critically endangered because its extent of occurrence is less than 100 square kilometers (39 square miles).
The major threat to this species is loss of its cloud forest habitat. People are clearing forests to create cattle pastures.
Critically Endangered Species: Transcaucasian Racerunner
The Transcaucasian racerunner (Eremias pleskei) is a lizard found on the Armenian Plateau, located in Armenia, Azerbaijan, Iran, and Turkey. The Transcaucasian racerunner is a critically endangered species because of a huge population decline, estimated at more than 80 percent during the past 10 years.
Threats to this species include the salination, or increased saltiness, of soil. Fertilizers used for agricultural development seep into the soil, increasing its saltiness. Racerunners live in and among the rocks and soil, and cannot adapt to the increased salt in their food and shelter. The racerunner is also losing habitat as people create trash dumps on their area of occupancy.
Critically Endangered Species: White Ferula Mushroom
The white ferula mushroom (Pleurotus nebrodensis) is a critically endangered species of fungus. The mushroom is critically endangered because its extent of occurrence is less than 100 square kilometers (39 square miles). It is only found in the northern part of the Italian island of Sicily, in the Mediterranean Sea.
The leading threats to white ferula mushrooms are loss of habitat and overharvesting. White ferula mushrooms are a gourmet food item. Farmers and amateur mushroom hunters harvest the fungus for food and profit. The mushrooms can be sold for up to $100 per kilogram (2.2 pounds).
Extinct In The Wild
A species is extinct in the wild when it only survives in cultivation (plants), in captivity (animals), or as a population well outside its established range. A species may be listed as extinct in the wild only after years of surveys have failed to record an individual in its native or expected habitat.
Extinct in the Wild: Scimitar-horned Oryx
The scimitar-horned oryx (Oryx dammah) is a species of antelope with long horns. Its range extends across northern Africa. The scimitar-horned oryx is listed as extinct in the wild because the last confirmed sighting of one was in 1988. Overhunting and habitat loss, including competition with domestic livestock, are the main reasons for the extinction of the oryx’s wild population.
Captive herds are now kept in protected areas of Tunisia, Senegal, and Morocco. Scimitar-horned oryxes are also found in many zoos.
Extinct in the Wild: Black Soft-shell Turtle
The black soft-shell turtle (Nilssonia nigricans) is a freshwater turtle that exists only in one man-made pond, at the Baizid Bostami Shrine near Chittagong, Bangladesh. The 150 to 300 turtles that live at the pond rely entirely on humans for food. Until 2000, black soft-shell turtles lived throughout the wetlands of the Brahmaputra River, feeding mostly on freshwater fish.
Unlike other animals that are extinct in the wild, black soft-shell turtles are not found in many zoos. The shrine’s caretakers do not allow anyone, including scientists, to take the turtles. The reptiles are considered to be the descendants of people who were miraculously turned into turtles by a saint during the 13th century.
Extinct in the Wild: Mt. Kaala Cyanea
The Mt. Kaala cyanea (Cyanea superba) is a large, flowering tree native to the island of Oahu, in the U.S. state of Hawaii. The Mt. Kaala cyanea has large, broad leaves and fleshy fruit. The tree is extinct in the wild largely because of invasive species. Non-native plants crowded the cyanea out of its habitat, and non-native animals such as pigs, rats, and slugs ate its fruit more quickly than it could reproduce.
Mt. Kaala cyanea trees survive in tropical nurseries and botanical gardens. Many botanists and conservationists look forward to establishing a new population in the wild.
A species is extinct when there is no reasonable doubt that the last remaining individual of that species has died.
Extinct: Cuban Macaw
The Cuban macaw (Ara tricolor) was a tropical parrot native to Cuba and a small Cuban island, Isla de la Juventud. Hunting and collecting the birds for pets led to the bird’s extinction. The last specimen of the Cuban macaw was collected in 1864.
Extinct: Ridley’s Stick Insect
Ridley’s stick insect (Pseudobactricia ridleyi) was native to the tropical jungle of the island of Singapore. This insect, whose long, segmented body resembled a tree limb, is only known through a single specimen, collected more than 100 years ago. During the 20th century, Singapore experienced rapid development. Almost the entire jungle was cleared, depriving the insect of its habitat.
Extinct: Sri Lankan Legume Tree
The Sri Lankan legume tree (Crudia zeylanica), native only to the island of Sri Lanka in the Indian Ocean, was a giant species of legume. Peas and peanuts are smaller types of legumes.
Habitat loss from development in the 20th century is the main reason the tree went extinct in the wild. A single specimen survived at the Royal Botanical Garden in Peradeniya, Sri Lanka, until 1990, when that, too, was lost.
Endangered Species and People
When a species is classified as endangered, governments and international organizations can work to protect it. Laws may limit hunting and destruction of the species’ habitat. Individuals and organizations that break these laws may face huge fines. Because of such actions, many species have recovered from their endangered status.
The brown pelican was taken off the endangered species list in 2009, for instance. This seabird is native to the coasts of North America and South America, as well as the islands of the Caribbean Sea. It is the state bird of the U.S. state of Louisiana. In 1970, the number of brown pelicans in the wild was estimated at 10,000. The bird was classified as vulnerable.
During the 1970s and 1980s, governments and conservation groups worked to help the brown pelican recover. Young chicks were reared in hatching sites, then released into the wild. Human access to nesting sites was severely restricted. The pesticide DDT, which damaged the eggs of the brown pelican, was banned. During the 1980s, the number of brown pelicans soared. In 1988, the IUCN “delisted” the brown pelican. The bird, whose population is now in the hundreds of thousands, is now in the category of least concern.
deformity or condition different from the normal or expected state of being.
in large amounts.
to adjust to new surroundings or a new situation.
the strategy of applying profit-making practices to the operation of farms and ranches.
the art and science of cultivating land for growing crops (farming) or raising livestock (ranching).
the distance above sea level.
science of the origin, development, and culture of human beings.
area of occupancy
geographic area where a specific population of a species resides, used to determine a species' level of conservation.
irregularly shaped planetary body, ranging from 6 meters (20 feet) to 933 kilometers (580 miles) in diameter, orbiting the sun between Mars and Jupiter.
layers of gases surrounding a planet or other celestial body.
type of huge, woody grass.
to prohibit or not allow.
having to do with the bottom of a deep body of water.
large predators, including tigers, lions, jaguars, and leopards.
scientist who studies living organisms.
place where plants and flowers are grown and displayed for education and study.
breed in captivity
to mate animals in a controlled environment.
animals who cooperate over a period of time to produce generations of offspring.
to reach a conclusion by mathematical or logical methods.
one of the top layers of a forest, formed by the thick leaves of very tall trees.
large area of grassland where cattle graze.
large farm where cattle are raised and bred for meat or leather.
large, spotted cat native to Africa.
game of strategy played by two players, each with 16 pieces moved across a checkered board.
rodent native to South America.
to identify or arrange by specific type or characteristic.
all weather conditions for a given location over a period of time.
gradual changes in all the interconnected weather elements on our planet.
wooded area, usually high-altitude, almost always covered by clouds and fog.
edge of land along the sea or other large body of water.
management of a natural resource to prevent exploitation, destruction, or neglect.
Convention on Biological Diversity
international treaty to sustain and protect the diversity of life on Earth.
145 million to 65 million years ago. The period ended with extinction of the dinosaurs and the rise of mammals.
level of conservation between "endangered" and "extinct in the wild."
to encourage the growth of something through work and attention.
type of plant native to Hawaii with large, broad leaves.
structure built across a river or other waterway to control the flow of water.
(dichloro-diphenyl-trichloroethane) toxic chemical used as an insecticide but illegal for most uses in the U.S. since 1972.
remains of something broken or destroyed; waste, or garbage.
to reduce or go down in number.
children, grandchildren, and other offspring.
construction or preparation of land for housing, industry, or agriculture.
very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.
animal that has been tamed for work or to be a pet.
to make something appear small by having it appear next to something much larger.
tree native to Africa that produces dark, hard timber.
irregular, recurring weather system that features a warm, eastern-flowing ocean current in the eastern Pacific Ocean.
to meet, especially unexpectedly.
organism threatened with extinction.
extent of occurrence
smallest area that could contain all the sites of a species' population, used to determine a species level of conservation.
no longer existing.
extinct in the wild
highest level of conservation of a living species, when the only living members of that species are protected in captivity such as zoos or aquariums.
process of complete disappearance of a species from Earth.
land cultivated for crops, livestock, or both.
nutrient-rich chemical substance (natural or manmade) applied to soil to encourage plant growth.
to punish, usually by charging an economic penalty or fee. Or, the penalty or fee itself.
flat part of a stringed instrument where the musician presses the string down to create a note.
industry or occupation of harvesting fish, either in the wild or through aquaculture.
(singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.
group in a species made up of members that are roughly the same age.
differences in the genes among individual members of a species.
high-quality, expensive, or difficult-to-prepare food.
environment where an organism lives throughout the year or for shorter periods of time.
to emerge from an egg.
large mammal native to Africa that lives near rivers.
long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.
collision or crash.
to produce offspring with close family members.
activity that produces goods and services.
unit made up of governments or groups in different countries, usually for a specific purpose.
International Union for the Conservation of Nature (IUCN)
environmental organization concerned with preserving natural ecosystems and habitats.
type of plant or animal that is not indigenous to a particular area and causes economic or environmental harm.
body of land surrounded by water.
tropical ecosystem filled with trees and underbrush.
type of seaweed.
lowest level of conservation, used when the population and habitat of a species are healthy.
type of plant with a pod that splits, with seeds in the middle, such as peanuts.
level of conservation
one of seven categories of a species' threat of extinction, assigned by the International Union for the Conservation of Nature: least concern, near threatened, vulnerable, endangered, critically endangered, extinct in the wild, and extinct.
animals raised for human use.
industry engaged in cutting down trees and moving the wood to sawmills.
last surviving Pinta Island tortoise.
long-tailed parrot native to the Americas.
type of metamorphic rock.
adult member of a species who is able to reproduce.
person who studies patterns and changes in Earth's atmosphere.
process of extracting ore from the Earth.
to observe and record behavior or data.
the system of growing one type of crop.
large cat native to North and South America. Also called a cougar, puma, catamount, and panther.
series or chain of mountains that are close together.
level of conservation between "least concern" and "vulnerable."
place where birds build nests and raise their young.
a type of plant or animal that is not indigenous to a particular area. Non-native species can sometimes cause economic or environmental harm as an invasive species.
the children of a person or animal.
antelope native to Africa.
to harvest aquatic life to the point where species become rare in the area.
to use more of a resource than can be replaced naturally.
to capture and kill enough animals to reduce their breeding population below sustainable levels.
type of bird with a large beak.
to survey and monitor an area by passing through it.
large marine bird with a big bill.
natural or manufactured substance used to kill organisms that threaten agriculture or are undesirable. Pesticides can be fungicides (which kill harmful fungi), insecticides (which kill harmful insects), herbicides (which kill harmful plants), or rodenticides (which kill harmful rodents.)
animal kept as a helper or companion.
lever, either black or white, which triggers a hammer to hit a specific string inside the body of a piano.
large region that is higher than the surrounding area and relatively flat.
to hunt, trap, or fish illegally.
toxic or containing dangerous chemicals.
introduction of harmful materials into the environment.
population reduction rate
rate at which the numbers of a specific species are shrinking.
calculation of a species' population and its area of occupancy that helps determine its conservation status.
probability of extinction
calculation of how long a species can survive without human protection.
area of tall, mostly evergreen trees and a high amount of rainfall.
to formally approve or confirm.
list defining the severity and causes of each species' threat of extinction. The Red List is maintained by the International Union for the Conservation of Nature (IUCN).
to lower or lessen.
to create offspring, by sexual or asexual means.
organs involved in an organism's reproduction.
order of mammals often characterized by long teeth for gnawing and nibbling.
large, brown-skinned potato often used for making french fries in fast food restaurants.
process where soils build up high salt content.
long, curved sword with a sharp outer edge, developed in the Middle East.
bird native to an aquatic environment.
marine algae. Seaweed can be composed of brown, green, or red algae, as well as "blue-green algae," which is actually bacteria.
to slowly flow through a border.
place of worship or spiritual devotion.
top layer of the Earth's surface where plants can grow.
bird with a recognizable vocal pattern.
native, geographic area in which an organism can be found. Range also refers to the geographic distribution of a particular species.
individual organism that is a typical example of its classification.
type of marine or freshwater large, long, bony fish.
use of resources in such a manner that they will never be exhausted.
habit or predictable way of behaving.
three levels of endangered species: vulnerable, endangered, and critically endangered.
organism that may soon become endangered.
point in a process that must be met to start a new stage in the process.
wood in an unfinished form, either trees or logs.
land-based turtle, usually with a tall, rounded shell.
top branches of a tree.
existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.
type of reptile with a shell encasing most of its body.
developed, densely populated area where most inhabitants have nonagricultural jobs.
all the plant life of a specific place.
plant with small flowers.
pathogenic agent that lives and multiplies in a living cell.
level of conservation between "near threatened" and "endangered." Vulnerable is the lowest of the "threatened" categories.
type of small songbird.
repeating or predictable changes in the Earth's atmosphere, such as winds, precipitation, and temperatures.
area of land covered by shallow water or saturated by water.
place where animals are kept for exhibition.