Environment

Zebras are several species of African equids united by their distinctive black and white striped coats. Their stripes come in different patterns, unique to each individual. They are generally social animals that live in small harems to large herds. Unlike their closest relatives the horses and donkeys, zebras have never been truly domesticated.

There are three species of zebras: the plains zebra, the Grévy’s zebra and the mountain zebra. The plains zebra and the mountain zebra belong to the subgenus Hippotigris, but Grévy’s zebra is the sole species of subgenus Dolichohippus. The latter resembles an ass, to which it is closely related, while the former two are more horse-like. All three belong to the genus Equus, along with other living equids.

The unique stripes of zebras make them one of the animals most familiar to people. They occur in a variety of habitats, such as grasslands, savannas, woodlands, thorny scrublands, mountains, and coastal hills. However, various anthropogenic factors have had a severe impact on zebra populations, in particular hunting for skins and habitat destruction.

Everytime I look at a zebra, I can’t figure out whether it’s black with white stripes or white with black stripes, and that frustrates me.

Jodi Picoult

Grévy’s zebra and the mountain zebra are endangered. While plains zebras are much more plentiful, one subspecies, the quagga, became extinct in the late 19th century – though there is currently a plan, called the Quagga Project, that aims to breed zebras that are phenotypically similar to the quagga in a process called breeding back.

The name “zebra” in English dates back to c. 1600, from Italian zebra, perhaps from Portuguese, which in turn is said to be Congolese. The Encarta Dictionary says its ultimate origin is uncertain, but perhaps it may come from Latin equiferus meaning “wild horse”; from equus and ferus .

The word was traditionally pronounced with a long initial vowel, but over the course of the 20th century, the pronunciation with the short initial vowel became the usual one in the UK and Commonwealth. The pronunciation with a long initial vowel remains standard in the United States.

The plains zebra (Equus quagga, formerly Equus burchelli) is the most common, and has or had about six subspecies distributed across much of southern and eastern Africa. It, or particular subspecies of it, have also been known as the common zebra, the dauw, Burchell’s zebra, Chapman’s zebra, Wahlberg’s zebra, Selous’ zebra, Grant’s zebra, Boehm’s zebra and the quagga.

Three quarters of the planet Earth is covered by water. A majority of the planet’s solid surface is abyssal plain, at depths between 4,000 and 5,500 metres (13,100 and 18,000 ft) below the surface of the oceans. The solid surface location on the planet closest to the centre of the orb is the Challenger Deep, located in the Mariana Trench at a depth of 10,924 metres (35,840 ft).

Although a number of human activities are conducted underwater—such as research, scuba diving for work or recreation, or even underwater warfare with submarines, this very extensive environment on planet Earth is hostile to humans in many ways and therefore little explored. But it can be explored by sonar, or more directly via manned or autonomous submersibles. The ocean floors have been surveyed via sonar to at least a coarse resolution; particularly-strategic areas have been mapped in detail, in the name of detecting enemy submarines, or aiding friendly ones, though the resulting maps may still be classified.

An immediate obstacle to human activity under water is the fact that human lungs cannot naturally function in this environment. Unlike the gills of fish, human lungs are adapted to the exchange of gases at atmospheric pressure, not liquids. Aside from simply having insufficient musculature to rapidly move water in and out of the lungs, a more significant problem for all air-breathing animals, such as mammals and birds, is that water contains so little dissolved oxygen compared with atmospheric air.

Nothing is softer or more flexible than water, yet nothing can resist it.

Lao Tzu

The density of water also causes problems that increase dramatically with depth. The atmospheric pressure at the surface is 14.7 pounds per square inch or around 100 kPa. A comparable water pressure occurs at a depth of only 10 m (33 ft) (9.8 m (32 ft) for sea water). Thus, at about 10 m below the surface, the water exerts twice the pressure (2 atmospheres or 200 kPa) on the body as air at surface level.

For solid objects like human bones and muscles, this added pressure is not much of a problem; but it is a problem for any air-filled spaces like the mouth, ears, paranasal sinuses and lungs. This is because the air in those spaces reduces in volume when under pressure and so does not provide those spaces with support from the higher outside pressure. Even at a depth of 8 ft underwater, an inability to equalize air pressure in the middle ear with outside water pressure can cause pain, and the tympanic membrane can rupture at depths under 10 ft (3 m).

The danger of pressure damage is greatest in shallow water because the rate of pressure change is greatest at the surface of the water. For example, the pressure increase between the surface and 10 m is 100% (100 kPa to 200 kPa), but the pressure increase from 30 m
With increasing depth underwater, sunlight is absorbed, and the amount of visible light diminishes.

Because absorption is greater for long wavelengths (red end of the visible spectrum) than for short wavelengths (blue end of the visible spectrum), the colour spectrum is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is turbid, in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m. At 100 m (330 ft) the light present from the sun is normally about 0.5% of that at the surface.

The euphotic depth is the depth at which light intensity falls to 1% of the value at the surface. This depth is dependent upon water clarity, being only a few metres underwater in a turbid estuary, but may reach up to 200 metres in the open ocean. At the euphotic depth, plants have no net energy gain from photosynthesis and thus cannot grow.

Wildlife traditionally refers to undomesticated animal species, but has come to include all plants, fungi, and other organisms that grow or live wild in an area without being introduced by humans.

Wildlife can be found in all ecosystems. Deserts, forests, rain forests, plains, grasslands, and other areas including the most developed urban sites, all have distinct forms of wildlife. While the term in popular culture usually refers to animals that are untouched by human factors, most scientists agree that much wildlife is affected by human activities.

Humans have historically tended to separate civilization from wildlife in a number of ways including the legal, social, and moral sense. Some animals, however, have adapted to suburban environments. This includes such animals as domesticated cats, dogs, mice, and gerbils.Some religions have often declared certain animals to be sacred, and in modern times concern for the natural environment has provoked activists to protest the exploitation of wildlife for human benefit or entertainment.

The global wildlife population has decreased by 52 percent between 1970 and 2014, according to a report by the World Wildlife Fund.

Some people hikes several days to reach to various regions to preserve wild animals using their best hiking boots for women and men.

Anthropologists believe that the Stone Age people and hunter-gatherers relied on wildlife, both plants and animals, for their food. In fact, some species may have been hunted to extinction by early human hunters. Today, hunting, fishing, and gathering wildlife is still a significant food source in some parts of the world.

Habitat for wildlife is continually shrinking – I can at least provide a way station.

Peter Coyote

In other areas, hunting and non-commercial fishing are mainly seen as a sport or recreation, with the edible meat as mostly a side benefit of it. Meat sourced from wildlife that is not traditionally regarded as game is known as bush meat. The increasing demand for wildlife as a source of traditional food in East Asia is decimating populations of sharks, primates, pangolins and other animals, which they believe have aphrodisiac properties.

In November 2008, almost 900 plucked and “oven-ready” owls and other protected wildlife species were confiscated by the Department of Wildlife and National Parks in Malaysia, according to TRAFFIC. The animals were believed to be bound for China, to be sold in wild meat restaurants. Most are listed in CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) which prohibits or restricts such trade.

Exploitation of wild populations has been a characteristic of modern man since our exodus from Africa 130,000 – 70,000 years ago. The rate of extinctions of entire species of plants and animals across the planet has been so high in the last few hundred years it is widely believed that we are in the sixth great extinction event on this planet; the Holocene Mass Extinction.

Destruction of wildlife does not always lead to an extinction of the species in question, however, the dramatic loss of entire species across Earth dominates any review of wildlife destruction as extinction is the level of damage to a wild population from which there is no return.