The zebra (Equus) is a placental mammal that belongs to the Equidae family. Their main distinctive feature is the black and white striped pattern that they present on their body. These are shown as a unique design that identifies each species. The skin is black and the coloration of the bands is due to melanin. The hairs that have this pigment take a black color, while those that do not have it are white.
There are three species: the common zebra (Equus quagga), Grevy's zebra (Equus grevyi) and the mountain zebraEquus zebra). They all inhabit the African continent, from where they originate, being distributed in specific regions. They tend to live in savannahs, thorn scrub, grasslands, coastal hills, and mountains..
Zebra populations have been negatively impacted by various anthropogenic factors, such as hunting and habitat destruction. Because of this, the IUCN has included all three species on its list of animals at risk of extinction..
These ungulates are most active during the day. At night, much of the group rests on the grass, while the dominant male watches over and protects the herd.
Article index
The first equidae existed in the Eocene, around 54 million years ago. These were small mammals, with three toes on each hind leg and four on the forelegs. Instead of claws they had helmets, but they had pads.
In the Miocene and Oligocene, this group of animals suffered several body adaptations, among which is having three fingers on each limb. During the Miocene, the lateral fingers progressively decreased in size, until the appearance of the Equus, that has only one functional finger.
Experts suggest that gender Equus is the product of the evolution of Dinohippus, being one of the first ancestors the Equus simplicidens, known as the american zebra.
This equid lived in the Pliocene and Pleistocene eras. Its body length was approximately 110 to 145 centimeters and it weighed 110 to 385 kilograms. Its body was stocky, with a thick neck, like that of a zebra, and a narrow and short skull, similar to a donkey..
Mitochondrial evidence supports the division suffered by the genus Equus. Two groups emerged from this, one of true horses and another group made up of donkeys and zebras..
Of this last group, the lineage corresponding to the donkeys may have been the first to separate, which probably occurred when the Equus came to the Old World. As for the zebras, the evidence seems to indicate that they were differentiated in Africa, from where they are endemic.
The size and weight of the zebra varies by species. Thus the common zebra (Equus quagga) weighs approximately 350 kilograms and is 2 to 2.6 meters long, with a tail of 0.5 meters in length.
Grevy's zebra (Equus grevyi) is larger, weighing 350 to 450 kilograms. As for its body, it measures from 2.5 to 2.75 meters, from head to tail. Its height, from the shoulder to the case of the leg, is approximately 1.5 meters.
In relation to the mountain zebra (Equus zebra), has a length of 2.1 to 2.6 meters, with a tail that measures between 40 and 55 centimeters. The weight of this species is around 204 and 372 kilograms.
Previously, the zebra was considered an animal with a white body, with black stripes. This statement was based on the fact that some have a totally white belly..
However, the embryological evidence shows that the skin color is dark and that the stripes and the white abdomen are a consequence of the pigmentation of the coat..
This happens by the action of specialized epithelial cells known as melanocytes, which are melanin, a pigment that darkens the skin (the hairs that are growing). Thus, those that contain melanin take a black color and those that lack it, are white.
In general, the stripes are vertical on the neck, head, trunk, and forequarters. As for the extremities and the back, the lines are arranged horizontally.
The common or plains zebra has an erect mane, with black and white lines. The black stripes on the body are wide and separated by white spaces. Between these two colors are interspersed faint lines of soft brown.
The face looks black, due to the bands, and the muzzle is dark. In almost all members of this species, the lines extend to the middle of the abdomen. On some occasions the stripes may be absent on the extremities, chest and sides.
As for the mountain zebra, the stripes are less thick than those of the common zebra, and do not reach the middle part of the ventral region. The mane is erect and the stripes are thicker. On the abdomen and chest there is a black line.
Grevy's zebra is characterized by a pattern of thin black and white stripes, with a white abdomen. The design of the lines on the mane is a continuation of those on the animal's face. In relation to the snout, it is not totally black, as in the other two species.
A distinctive aspect of this species is the white border that surrounds the mouth and nose. In addition, it has a thick dorsal stripe, which has thin white bands on the sides. He has a dark brown spot on his face.
The zebra has four types of movements to move; trot, walk, gallop and fast gallop. Generally, it is usually slower than the horse, but it has a great resistance, which helps it escape from the threat.
When chased, it can zigzag from side to side, making it difficult for its predator to attack. If cornered, the zebra gets up on two legs and will kick or bite the attacker.
This animal has excellent eyesight. Like the vast majority of ungulates, the eyes are located on the sides of the head, giving it a wide field of vision. In addition, the sense of hearing is highly developed. As for your ears, you can turn them in almost any direction.
Zebra teeth have adaptations for grazing. Thus, the lower and upper incisors are strong, allowing it to efficiently cut grass. In addition, they have large teeth with a high crown, which facilitates the crushing and grinding of grasses rich in silicate..
Animal Kingdom.
Subkingdom: Bilateria.
Phylum: Chordata.
Subfilum: Vertebrate.
Superclass: Tetrapoda.
Class: Mammalia.
Subclass: Theria.
Infraclass: Eutheria.
Order: Perissodactyla.
Family: Equidae.
Gender: Equus.
Subgenre: Equus (Hippotigris).
Species
-Equus grevyi.
-Equus zebra.
-Equus quagga.
Subspecies:
Equus quagga boehmi.
Equus quagga chapmani.
Equus quagga quagga.
Equus quagga borensis.
Equus quagga crawshayi.
Equus quagga burchellii.
There is a controversy regarding the taxonomic classification of the Equus hartmannae. Some specialists consider it as a species, while others believe that it is part of a subspecies of the Equus zebra, so, in this case, its scientific nomenclature is Equus zebra hartmannae.
The zebra is native to Africa, yet each species thrives in its own area. In the case of the common zebra, it lives in the grasslands and forests of southern and eastern Africa. Grevy's zebra inhabits northern Kenya and the arid grasslands of Ethiopia. As for the mountain zebra, it is found in Namibia, South Africa and Angola.
This African species is found in Ethiopia, in the south and east of the country, in the Danakil Depression, in the Awash Valley and in the Rift Valley. It also inhabits some reservations in northern Kenya. Populations have disappeared from Djibouti, Eritrea, Somalia and Sudan.
Its natural habitat is made up of semi-desert areas, where there are mosaics of scrub and grasslands. Also found in floodplain grasslands.
In Mexico it is considered an exotic species, found in the center and north of the country, in the State of Mexico and in Tamaulipas. There it lives in tropical deciduous forests and xerophilous scrub..
The Equus quagga is distributed in central Angola, Botswana, southern Ethiopia, Kenya, Malawi, eastern South Africa, Tanzania, Uganda, Zambia and Zimbabwe.
The common zebra inhabits open savannahs, scrublands, tropical grasslands, and open forests. Occasionally it can be found in mountainous and not very steep places, up to 4,400 meters above sea level..
This species is frequently found in steppes, forests and savannas with firm ground, but where there are bodies of water. In addition, it prefers regions with an abundance of short grasses, although it can adapt to those with larger grasses..
It was introduced to northern Mexico and now resides in Chihuahua, Coahuila, Durango, Nuevo León, Querétaro, Sonora, Tamaulipas, and Veracruz. In these places it lives in grasslands, xerophilous shrubs and in tropical evergreen forests..
This zebra is distributed in the cliffs near the sea and in the arid mountains of Angola. Also lives in Namibia, western South Africa and southern Cape Province.
Regarding the types of vegetation, the Equus zebra It is found in tropical savannas, temperate mountain grasslands, tropical scrublands, and in the Karoo highlands. In Mexico it is within the group of exotic species. It currently occupies various areas in Coahuila and Tamaulipas, where it inhabits xerophilous scrub..
In general, the populations of the three species have decreased. Many are the factors that have influenced this situation, but mainly poaching is found. Because of this, the IUCN has included the zebra in the list of endangered animals..
Each species is categorized at different levels. Thus, the Equus grevyi is considered in danger of extinction, while in the Equus quagga, the population has grown slightly, so its risk of extinction is lower.
Regarding the Equus zebra, the number of zebras registered in their natural habitat is low and it is exposed to various threats that make it vulnerable to further decline.
Throughout history, man has hunted the zebra almost to extinction, as happened in the 1930s in Cape Town, South Africa. The reason for its capture is to commercialize its meat and skin, as well as some organs that are used for medicinal purposes..
Also, this ungulate competes with cattle for forage, which is why it is sometimes slaughtered by man, to protect his herd..
Man has cut down and fragmented the different ecosystems where zebras live. The lands are being used for agricultural, livestock, urban, recreational and tourist purposes. This brings dire consequences, among which the decrease in the flow of natural water sources stands out..
Animal access to rivers and streams is declining in several regions of Africa. Likewise, the flows of some of these have been reduced.
This problem is critical in the Ewaso Ng'iro River, in Kenya, where the extraction of water to be used for irrigation of plantations reduced its flow by up to almost 90%, in the dry season. On the other hand, the enclosure of the areas can hinder the migration corridors, in addition to preventing the zebras from reaching the streams to drink water.
The introduction of livestock breeding areas creates competition for foraging, further exposing the zebra to the spread of diseases such as babesiosis and anthrax.
Recently in Kenya there was an anthrax outbreak, in which more than 50 zebras died. This condition is a potential threat, especially for those small populations that are at risk of extinction..
Zebra communities are severely affected by the effects of extreme weather and drought that afflict the regions where they live.
Currently, the greatest threat to the mountain zebra (Equus zebra), is the loss of their genetic diversity, produced by inbreeding. In particular, this species lives in small populations, which prevent genetic exchange, making it more vulnerable to certain diseases..
The main problem for the species living in Cape Town is the risk of hybridization with the plains zebra and Hartmann's mountain zebra. The researchers attribute this crossing between species to the overlapping of territory.
However, they point out that it can also be caused by the fencing that divides the areas where they live, which keeps them in close contact throughout the year..
This African ungulate is found in numerous areas that are under the protection of national and international organizations.
Some of these refuges are the Serengeti National Park (Tanzania), the Hwange National Park (Zimbabwe), the Tsavo and Maasai Mara (Kenya), the Kruger National Park (South Africa) and the Etosha National Park (Namibia).
Zebras have two different types of societies. In one, typical of the common and mountain zebra, the males and females form family groups where the young and the young are also up to two years old. In this harem, the couple lives together for years and the female joins a particular male.
As for the other type of society, typical of Grevy's zebras, female groupings are short-lived and females frequently roam among groups without males. Thus, the female can mate with several males.
For the male, both systems are polygamous, since they are reproductively active and the dominant one can reproduce with more than one female..
In the common zebra, polygyny entails defense of the harem, due to the strong association that exists between group members. On the contrary, in Grevy's zebras it implies the protection of resources, since the male defends the grazing areas where the females are..
The female has two ovaries, which are about 5 cm in length. The eggs produced reach the uterus thanks to the oviducts, which connect with one of the two uterine horns. The caudal end of the uterus, known as the cervix, enters the vagina. This organ is elastic and measures between 15 and 20 cm long.
The outer opening of the vagina is located ventral to the rectum. As for the mammary glands, the zebra has two, each with two ducts that have an outlet to the outside.
In the male, the testicles are in the scrotum, located between the back of the penis and the thighs. From each testicle comes a vas deferens, which enlarges as it passes through the bladder, forming blisters. These open at the beginning of the urethra. This organ passes around the pubic syphilis towards the penis, where it is protected by the foreskin..
Females sexually mature earlier than males, so they can have their first offspring at three years, while males reproduce between five or six years.
The zebra goes into heat in the rainy season, where food sources abound. Estrus can last a little over a week. As for gestation, it usually lasts between 361 and 390 days.
At the time of parturition, the female lies on her side, shortly after the head and forelegs of the young are expelled. Next, the rest of the body comes out. At that moment, the newborn tries to get up, thus breaking the amniotic sac and the umbilical cord..
During this process, the male remains close to the female, between 10 and 50 meters from her. At birth, the calf weighs 25 to 40 kilograms and joins the group together with its mother.
Zebras are strict herbivorous animals, mainly feeding on tough, fibrous grasses. Sometimes they can browse and eat herbs. Among the favorites is the Pennisetum schimperi, a herbaceous species little used by cattle and other ungulates.
Also, they tend to consume grasses of the genera Chrysopogon, Enteropogon Y Cenchrus. Of these they can eat their leaves, stems and the tender shoots.
These mammals graze for several hours a day and use their strong incisor teeth to cut grass. The food then passes to the back teeth, which grind and grind it. The fact that they chew food for a long time causes the teeth to wear out, so the growth of these is constant.
As the dry season approaches, the vegetation dries up, so the herds move to other regions to find fresh grass and water.
The availability of bodies of water is a pressing need for zebras, especially in the dry season. This species usually digs wells in dry riverbeds, in order to obtain underground water. Once they find the water source, they defend it from other animals that try to access it.
The digestion of food occurs in the cecum, where bacteria act to break down cellulose. Cecal digestion of zebra is less efficient in pasture processing than digestion of ruminants. To compensate for this, the zebra ingests more food.
Zebras communicate with each other using sounds and facial expressions. Among the vocalizations are the snorting, barking and braying. For example, when they detect the presence of a predator, they hold their ears pricked, their heads held high, and they bray loudly..
As for gestures, they can open their eyes widely or move their lips, leaving their teeth bare. The ears usually represent your state of mind. When they are scared, it pushes them forward and if they are angry, it pulls them back.
Another very frequent habit in these African mammals is mutual grooming, which they perform to strengthen ties between group members..
In relation to the males, they are very territorial. They mark the boundaries of their area, for which they generally use their feces. If they detect the approach of a predator, the leader alerts the group, vocalizing a high-pitched and loud snort..
The leader of the group will remain in a firm position, while the herd flees, moving in a zigzag fashion. If the situation turns aggressive, you can fight the bully. For this he lowers his head, stretching his neck and exposing his teeth. If necessary, he can kick the other, with such force that it usually causes serious injuries..
For decades, researchers have tried to explain the purpose of the black and white stripe design on the body of zebras. This has led to various theories, each with its own reasoning.
One of these refers to the fact that the purpose of the band pattern is to prevent the animal from being infected by the horse fly. This insect can transmit various pathogens to the zebra, causing some diseases such as anaplasmosis and equine infectious anemia..
According to this approach, these stripes create a kind of optical illusion. This disrupts the pattern of polarized light that is reflected from dark surfaces, to which flies are attracted. Thus, for example, the coat of the zebra is less attractive than the smooth tone of the horse.
In 2019, a study was carried out in Great Britain, where it was shown that horse flies attacked horses more frequently than zebras, probably due to the confusion created by the striped design of these.
Other specialists have suggested that the advantage of the bands is that they help to camouflage the zebra with its environment or to confuse its predators..
Researchers at the University of California, Los Angeles, conducted a study on the influence of environmental variables on stripe patterns in common zebras that live from central to southern Africa.
This group suggests that these ungulates need an additional cooling mechanism, since their eating habit of eating for long hours maintains them much of the time under the high temperatures of the African climate.
As a result of their research, they identified that common zebras that had the most defined dorsal stripes lived in the north of their range, where temperatures are highest. In contrast, those with the least defined bands were to the south, where the ambient temperature is lower..
They suggested that this particular design is likely to serve multiple purposes. For example, the lines on the back may contribute to thermoregulation, while the stripes on the legs may help keep horse flies from landing on the animal..
Yet No Comments