Extinction and Endangered Species - Defining And Naming Life On Earth, Biodiversity, What Are Endangered Species?, Mass Extinction, U.s. History—some Extinctions And Some Close Calls
animals human survival living
Earth is richly supplied with different types of living organisms, including animals, plants, fungi, and bacteria. Various living organisms co-exist in their environments, forming complex, interrelated communities. Living organisms depend on one another for nutrients, shelter, and other benefits. The extinction of any one
species can set off a chain reaction that affects many other species, particularly if the loss occurs near the bottom of the food chain. For example, the extinction of a particular insect or plant might seem inconsequential. However, there may be fish or small animals that depend on that resource for foodstuff. The loss can threaten the survival of these creatures, and larger predators that prey
upon them. Extinction can have a ripple effect that spreads throughout nature.
In addition to its biological consequences, extinction poses a moral dilemma for humans, the only species capable of saving the others. The presence of humans on the planet has affected all other life forms, particularly plants and animals. Human lifestyles have proven to be incompatible with the survival of some other
species. Purposeful efforts have been made to eliminate animals that prey on people, livestock, crops, or pose any threat to human livelihoods. Some wild animals have been decimated by human desire for meat, hides, fur, or other body parts with commercial value. Likewise demand for land, water, timber, and other natural resources has left many wild plants and animals with little to no suitable
habitat. Humans have also affected nature by introducing nonnative species to local areas and producing pollutants that have a negative impact on the environment. The combination of these anthropogenic (human-related) effects with natural obstacles that limit survival, such as disease or low birthrates, have proven to be too much for some species to overcome. They have no chance of survival
without human help.
As a result, societies have difficult choices to make about the amount of effort and money they are willing to spend to keep imperiled species from becoming extinct. Will people accept limits on their property rights, recreational activities, and means of livelihood to save a plant or animal? Should saving such popular species
as whales and dolphins take priority over saving obscure, annoying, or feared species? Is it the responsibility of humans to save every kind of life form from disappearing, or is extinction an inevitable part of nature, in which the strong survive and the weak perish? These are some of the difficult questions that people face as they ponder the fate of other species living on this planet.
Living organisms are named and categorized according to a taxonomy, a hierarchical system of order based on the natural relationships among all types of life. For example, Table 1.1 shows the taxonomic chart for blue whales, the largest creatures on Earth. Blue whales are described by eight taxonomic levels ending with
"species." A species is a term assigned to a group of organisms t…
Biodiversity is short for biological diversity. It refers to the richness and variety of living organisms across the planet. Biodiversity is important at levels within the taxonomic table and at the genetic level. For example, all humans are members of one species—Homo sapiens—but humans can vary widely in their personal
characteristics, such as race, hair color, and eye color. These…
A species is described as extinct when no living members remain. Scientists know from the study of fossils that dinosaurs, mammoths, saber-toothed cats, and countless other animal and plant species that once lived on Earth no longer exist. These species have "died out", or become extinct. Once a species is extinct, there is no
way to bring it back. The U.S. government defines endange…
In the billions of years since life began on Earth, species have formed, existed, and then become extinct. Scientists call the natural extinction of a few species per million years a background, or normal, rate. When the extinction rate doubles for many different groups of plants and animals at the same time, this is described
as a mass extinction. Mass extinctions have occurred infrequently in Ea…
Colonization of the New World by European settlers severely depleted the ranks of some native wild species. The introduction of livestock brought new animal diseases that devastated some native animals. Widespread hunting and trapping led to the demise of other species. During the early 1800s the United States was home to
millions, perhaps billions, of passenger pigeons. These migratory birds trav…
Since 1960 the International Union for the Conservation of Nature and Natural Resources has compiled the IUCN Red List of Threatened Species, which aims to examine the status of biological species across the globe. The so-called "Red List" categorizes species based on the level of risk of their extinction in the wild, as
follows: The IUCN refers to species in all of these categories …
Environmental issues, which have a tendency to pit conservation against business or economic development, are often hotly debated. With respect to current threats to biodiversity, some critics argue that the scale of loss is not as great as we imagine. They point to uncertainty regarding the total number of species, as well as
the geographic distributions of species. Other challengers claim that l…
Proponents of conservation believe that saving species from extinction is important for many reasons. Species have both aesthetic and recreational value, as the tremendous popularity of zoos, wildlife safaris, recreational hiking, and wildlife watching (bird watching, whale watching, etc.) indicate. Wildlife also has
educational and scientific value. In addition, because all species depend on othe…
Experts believe that the increasing loss and decline of species cannot be attributed to natural processes, but results instead from the destructive effect of human activities. People hunt and collect wildlife. They destroy natural habitats by clearing trees and filling swamps for development. Aquatic habitats are altered or
destroyed by the building of dams. Humans also poison habitats with pollut…
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