Elephants are the largest living land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae and the order Proboscidea; extinct relatives include mammoths and mastodons. Distinctive features of elephants include a long proboscis called a trunk, tusks, large ear flaps, pillar-like legs, and tough but sensitive grey skin. The trunk is prehensile, bringing food and water to the mouth and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears and convex or level backs.
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems.
The common warthog is a wild member of the pig family (Suidae) found in grassland, savanna, and woodland in sub-Saharan Africa. In the past, it was commonly treated as a subspecies of P. aethiopicus, but today that scientific name is restricted to the desert warthog of northern Kenya, Somalia, and eastern Ethiopia.
The impala or rooibok is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus Aepyceros, and tribe Aepycerotini, it was first described to Europeans by German zoologist Hinrich Lichtenstein in 1812. Two subspecies are recognised—the grassland-dwelling common impala, and the larger and darker black-faced impala, which lives in slightly more arid, scrubland environments. The impala reaches 70–92 cm (28–36 in) at the shoulder and weighs 40–76 kg (88–168 lb). It features a glossy, reddish brown coat. The male's slender, lyre-shaped horns are 45–92 cm (18–36 in) long.
The African forest elephant is one of the two living species of African elephant. It is native to humid tropical forests in West Africa and the Congo Basin. It is the smallest of the three living elephant species, reaching a shoulder height of 2.4 m. As with other African elephants, both sexes have straight, down-pointing tusks, which begin to grow once the animals reach 1–3 years old. The forest elephant lives in highly sociable family groups of up to 20 individuals. Since they forage primarily on leaves, seeds, fruit, and tree bark, they have often been referred to as the 'megagardener of the forest'; the species is one of many that contributes significantly to maintaining the composition, diversity and structure of the Guinean Forests of West Africa and the Congolese rainforests. Seeds of various plants will go through the elephant's digestive tract and eventually pass through in the animal's droppings, thus helping to maintain the spread and biodiversity of the forests.
The Asian elephant, also known as the Asiatic elephant, is a species of elephant distributed throughout the Indian subcontinent and Southeast Asia, from India in the west to Borneo in the east, and Nepal in the north to Sumatra in the south. Three subspecies are recognised—E. m. maximus, E. m. indicus and E. m. sumatranus. The Asian elephant is characterised by its long trunk with a single finger-like processing; large tusks in males; laterally folded large ears but smaller in contrast to African elephants; and wrinkled grey skin. The skin is smoother than African elephants and may be depigmented on the trunk, ears or neck. Adult males average 4 t in weight, and females 2.7 t.
Musth or must is a periodic condition in bull (male) elephants characterized by aggressive behavior and accompanied by a large rise in reproductive hormones. It has been known in Asian elephants since 3000 years, but was only described in African elephants in 1981. There is evidence that it occurred in extinct proboscideans.
The rut is the mating season of certain mammals, which includes ruminants such as deer, sheep, camels, goats, pronghorns, bison, giraffes and antelopes, and extends to others such as skunks and elephants. The rut is characterized in males by an increase in testosterone, exaggerated sexual dimorphisms, increased aggression, and increased interest in females. The males of the species may mark themselves with mud, undergo physiological changes or perform characteristic displays in order to make themselves more visually appealing to the females. Males also use olfaction to entice females to mate using secretions from glands and soaking in their own urine. Deer will also leave their own personal scent marking around by urinating down their own legs with the urine soaking the hair that covers their tarsal glands. Male deer do these most often during breeding season.
African elephants are members of the genus Loxodonta comprising two living elephant species, the African bush elephant and the smaller African forest elephant. Both are social herbivores with grey skin, but differ in the size and colour of their tusks and in the shape and size of their ears and skulls.
The anal glands or anal sacs are small glands near the anus in many mammals. They are situated in between the external anal sphincter muscle and internal anal sphincter muscle. Their function in humans is unclear.
The estrous cycle is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases, otherwise known as "rest" phases, or by pregnancies. Typically, estrous cycles repeat until death. These cycles are widely variable in duration and frequency depending on the species. Some animals may display bloody vaginal discharge, often mistaken for menstruation. Many mammals used in commercial agriculture, such as cattle and sheep, may have their estrous cycles artificially controlled with hormonal medications for optimum productivity. The male equivalent, seen primarily in ruminants, is called rut.
para-Cresol, also 4-methylphenol, is an organic compound with the formula CH3C6H4(OH). It is a colourless solid that is widely used intermediate in the production of other chemicals. It is a derivative of phenol and is an isomer of o-cresol and m-cresol.
meta-Cresol, also 3-methylphenol, is an organic compound with the formula CH3C6H4(OH). It is a colourless, viscous liquid that is used as an intermediate in the production of other chemicals. It is a derivative of phenol and is an isomer of p-cresol and o-cresol.
The Indian elephant is one of three extant recognized subspecies of the Asian elephant, native to mainland Asia. The species is smaller than the African elephant species with a convex back and the highest body point on its head. The species exhibits significant sexual dimorphism with a male reaching an average shoulder height of about 3.2 m (10 ft) and weighing up to 5,400 kg (11,900 lb) whereas a female reaches an average shoulder height of about 2.54 m (8.3 ft) and weighs up to 4,160 kg (9,170 lb). It has a broader skull with a concave forehead, two large laterally folded ears and a large trunk. It has grey colored smooth skin with four large legs and a long tail.
The African bush elephant, also known as the African savanna elephant, is one of two extant African elephant species and one of three extant elephant species. It is the largest living terrestrial animal, with bulls reaching an average shoulder height of 3.04–3.36 metres (10.0–11.0 ft) and a body mass of 5.2–6.9 tonnes (11,500–15,200 lb), with the largest recorded specimen having a shoulder height of 3.96 metres (13.0 ft) and a body mass of 10.4 tonnes (22,900 lb).
The preorbital gland is a paired exocrine gland found in many species of artiodactyls, which is homologous to the lacrimal gland found in humans. These glands are trenchlike slits of dark blue to black, nearly bare skin extending from the medial canthus of each eye. They are lined by a combination of sebaceous and sudoriferous glands, and they produce secretions which contain pheromones and other semiochemical compounds. Ungulates frequently deposit these secretions on twigs and grass as a means of communication with other animals.
Elephants can be found in various captive facilities such as a zoo, sanctuary, circus, or camp, usually under veterinary supervision. They can be used for educational, entertainment, or work purposes.
Sexual selection in mammals is a process the study of which started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, consisting of male–male competition and mate choice that mold the development of future phenotypes in a population for a given species.
Joyce Hatheway Poole is a biologist, ethologist, conservationist, and co-founder/scientific director of ElephantVoices. She is a world authority on elephant reproductive, communicative, and cognitive behavior.
Elephant communication includes touching, visual displays, vocalisations, seismic vibrations, and semiochemicals.
