There are five living species of rhinos in Africa and Asia. The largest, the White Rhino, is about twice the size and weight of the smallest, the relatively diminutive Sumatran Rhino. All have much in common regarding their behavior and anatomy, but there are significant differences as well, indicating how, over time, the individual species have adapted to their environmental circumstances.
MEET THE RHINOS
RHINOS—A QUICK INTRODUCTION
The ancestors of the rhinos arrived on the stage of life about 55 million years ago and over the passage of time, drifting continents, altering climate and sudden cataclysmic events have all presented this family of redoubtable pachyderms with challenges to their existence. At times, rhinos have flourished and at others, not. But their lineage has persisted, and today five species survive.
Little more than 200 years ago, rhinos in their hundreds of thousands—if not millions—roamed through much of Africa and large parts of Asia. A century later the Asian species were on their knees, while in Africa numbers had also fallen dramatically, and by the mid-1900s they too teetered on the brink of extinction.
To find out how and why this happened, where rhinos stand today and what is to be done to ensure their survival, click on the sections below.

By the latter decades of the 20th century, the efforts of a few heroic individuals had turned the tide in southern Africa and India, at least. Any respite, however, was to prove short-lived. From 1970 to the mid-1990s Black Rhinos were nearly wiped out, such was the sudden, huge demand for horn to fashion traditional dagger handles in the Middle East. This bloodletting was staunched and a short period of calm ensued. But from 2008 South Africa, by then home to 85 percent of all rhinos worldwide, came increasingly under siege owing to a renewed and expanding market for rhino horn, predominantly in Asia. South Africa’s White Rhinos have been particularly badly affected, so much so that the country’s overall rhino numbers had fallen to some 65 percent of the global total at the end of 2017.
In 2014 global rhino deaths at the hands of poachers rose to almost 1,400—nearly 90 percent of them in South Africa. Official statistics show that the killings have since leveled off and dropped slightly, but they remain unacceptably high and the battle is far from won.

Views on the best strategies for rhino survival differ widely, often vehemently. Rhino Review gives voice to all sides, attempting to present an evenhanded collation of the pros and cons of each across the full spectrum of opinion. It examines the measures being taken to counter poaching and evaluates their effectiveness. In other words, it looks at what is being done and what could be done better or differently to have lasting success. As is so often said, however, there is no silver bullet when it comes to saving the world’s rhinos. See the sections ‘Protecting Rhinos‘ and ‘A Rhino Road Map‘ for a comprehensive overview of the range of positive actions needed.
And most important of all, Rhino Review shows how we, as ordinary concerned citizens, can make the difference in ensuring that Africa and Asia’s rhinos survive long into the future.
RHINOS IN BRIEF
Explore the lives, behavior and habits of the five living rhino species in Africa and Asia. Learn about their population numbers, ranges, habitats, outstanding features, biology, diet, mobility, calls and communication, social behavior, contact with humans, and their conservation status.
RHINO ANATOMY
Without doubt, the rhino’s most renowned anatomical feature is its horn—mostly for all the wrong reasons. In many respects rhino physiology and anatomy function as for any other mammal, but they do exhibit a number of adaptations, other than their horns, that are particularly beneficial to their way of life. Roll your cursor over the labels in this infographic to find out how rhinos “work”.

Horn
In most horned mammals the horn has a living, bony core covered by a thin sheath of keratin. Rhino horn differs in that it is almost entirely made up of keratin. Find out more about the composition and structure of horn, its much-debated pharmacological attributes, and the many myths and legends that surround it—see “All About Horn”.
Brain
The rhino’s brain is on the small side for a creature of its size. It typically weighs 14–21 ounces (400–600 grams) but basically, it’s like that of any other mammal in its general structure and organization. That said the rhino brain has not been well studied in any detail, but recently, scientists at South Africa’s University of the Witwatersrand have observed some interesting differences in the brains of Black and White Rhinos. Find out more about this study in “Rhino Brains—Different Strengths for Different Lifestyles”.
Ears & Hearing
The rhino has an excellent sense of hearing. Its cup or tube-shaped ears are sensitive to the slightest sound and can be rotated to pick up audio signals from any direction with equal intensity.
Hump
Rhinos have powerful, well-developed shoulder and neck regions, a feature most pronounced in White Rhinos which have noticeable “humps”. There are three components to these humps: a thick, outer covering of skin tissue, an underlying layer of fat, and a mass of muscle and ligament joining the base of the skull to the last vertebrae in the neck. This ligament is absent or poorly developed in many mammals, but for those adapted for running, a well developed ligament helps to support the head and prevents excessive stress on the muscles of the region. It is logical, therefore, given their overall bulk, need for mobility and comparatively massive heads, that this ligament in rhinos is particularly strong, especially in White Rhinos which are specialist grazers and for much of the time carry their heads close to the ground.
Scent Marking
The Indian and Javan Rhinos have pedal glands that exude a thick secretion almost continuously. In this way they scent mark along their trails—important signals to other rhinos moving through the same area. The Sumatran Rhino and the two African species lack these glands.
Digestive System
Rhinos are vegetarians and either grazers or browsers or a combination of both. Because plant matter has a high cellulose component—cellulose is the tough fibrous material that gives plants their strength—the rhino’s gut needs to break it down before nutrients can be absorbed into the body. Find out more in “Coping With a Rhino Diet”.
Feet
It would be hard to describe any aspect of a rhino as dainty, but they do have rather small feet for their overall size.Scientists at the Royal Veterinary College in the UK are trying work out how one of the heaviest land creatures on earth manages on such relatively tiny feet. Rhinos are three-toed and belong to a small, ancient group of browsing and grazing mammals known as perrisodactyls (meaning odd-toed) which includes horses and tapirs. The center toe bears most of the weight. Notwithstanding their small feet and short stumpy legs, rhinos are remarkably agile and fast. The Black Rhino is a real speedster and can reach 35 miles per hour (55 kilometers per hour) over short distances.
Lips
The White Rhino has a distinctive wide, or square-lipped mouth profile which is perfectly suited to cropping the grasses that make up its diet. By contrast, the Black Rhino (a specialist browser) and the Asian species (mixed feeders), all have pointed, prehensile upper lips that enable the animals to grasp and strip leaves, twigs and small branches.
Nose & Smell
The rhino’s sense of smell is very important to its safety and for finding its way around its territory, as it helps the animal to be aware of things it may not be able to see or hear. The large nostrils are positioned at the tip of the snout. Each one is richly supplied with millions of extremely sensitive sensory cells that are able to register subtle odors in the air and then relay them to the olfactory center of the brain for interpretation.
Teeth
Rhinos have powerful molars and premolars in the upper and lower jaws which are used for grinding the coarse plant material that makes up their diet. The two African rhino species lack incisors, but the Asian species are armed with long, sharp, tusk-like incisors in the lower jaw. These are present in males and females, but are longer in males—they can reach a length of more than five inches (13 centimeters) in dominant male Indian Rhinos and are used not for feeding, but as potentially lethal weapons when competing for access to breeding females. African rhinos spar with their horns in dominance battles.
Eyes & Eyesight
Rhinos have small eyes for their body size and their positioning on the side of the head means that they lack binocular vision. But are rhinos as poor sighted as they are made out to be? Find out more in “Shortsighted? Not Really”.
Heart
The rhino is a big animal and it needs a big pump to circulate blood to and from all parts of its body. The White Rhino—the largest of all the living rhinos—has a heart weighing about 22 pounds (10 kilograms) which is about double that of the comparatively small Sumatran Rhino. By comparison, an elephant’s heart can weigh between 26 and 46 pounds (12–21 kilograms), while our human heart weighs in at a puny 11 ounces (312 grams). The creature with the biggest heart of all is the blue whale—a mighty 400 pounds (181 kilograms).
Skin
Rhino skin is tough and thick. In White Rhinos for example, it can be nearly two inches thick (50 millimeters) in places – that is thicker than hippo skin and substantially more so than an elephant’s hide which is little more than half an inch thick (about 17millimeters).




NAMING RHINOS
We have African rhinos (Black and White) and Asian rhinos (Indian, Javan and Sumatran) and surely these names are enough to separate them accurately? In everyday terms they are, but science needs to be more precise than that and a whole branch of biology known as taxonomy is devoted to the purpose of naming, describing and classifying not only rhinos but all the world’s life forms—plants, fungi, animals of the land, sea and sky, and millions of microorganisms. Rhinos are no exception.

Most would agree, though, that the moniker of ‘Father of Taxonomy’ rightly goes to Carl Linnaeus (Carl von Linné) the Swedish botanist who in the mid 1700s created the two part, or binomial, names for species that we use to this day: the combination of the genus of the organism with a specific epithet, or adjective, for a more precise classification. The Indian Rhino, for example, is named Rhinoceros (the genus) and unicornis (the specific adjective) which together give us the scientific name for the ‘rhino with one horn.’ It is not unlike having a surname followed by a first name.
But it doesn’t stop there, as all living organisms are further organized into ever broader groupings until we encompass all life.

But now the science of taxonomy also includes genetic and biochemical analysis as well. This aspect of taxonomy, known as cladistics, traces the evolution of organisms back through shared common ancestors using morphological and molecular data to visualize evolutionary history and relationships between species.

But why is it so important to scientifically name as many species as we possibly can? Well, global biodiversity is being lost at an unprecedented rate and some scientists have begun to argue that we are in the middle of a period of mass extinction. There have been other periods of great loss—five such previous episodes are thought to have happened since the planet was born—but this is the first where a single species has played such a destructive role…us.
Urgent decisions are needed to reverse this looming disaster. Protected areas need to be secured, consolidated and expanded, and our destructive processes everywhere need to be stopped or at least modified. But how do we do this if we don’t even know and understand the life forms that need protecting and where they live?
How do countries, developed and developing, ensure that they can reap the benefits, in perpetuity, of healthy ecosystems and the services they provide if they don’t know about the life forms that make up those ecosystems in the first place? And this is where taxonomy is so vital, for it provides the basic understanding of the species and their lineages that make up the building blocks of the Earth’s biodiversity. It is as important for understanding the five surviving rhino species and their lineage as it is for every other living thing.

WHITE RHINO
The White Rhino (Ceratotherium simum), the largest of all living rhinos, was given its scientific name by the English explorer William John Burchell in 1817. Ceratotherium comes from joining the two Greek words keras, meaning horn and thérion meaning wild beast, while simum comes from the Greek simós which literally means flat-nosed, a reference to the animal’s characteristically wide and blunt snout.
Currently two subspecies of the White Rhino are recognized:
- the Southern White Rhino (C. s. simum)
- the Northern White Rhino (C. s. cottoni), which was named by the English naturalist Richard Lydekker in 1908…’cottoni’ being a tribute to the English explorer William Cotton Oswell, at one time a colleague of David Livingstone.
BLACK RHINO
The Black Rhino (Diceros bicornis) was given its somewhat prosaic scientific name by Linnaeus way back in 1758: Di means two and cerato means horn in Greek, while the Latin bi and cornis combine to mean the same. How Linnaeus arrived at his decision is somewhat puzzling and is likely to have been based on the skull of a single-horned (Indian) Rhino with a second horn added by the original collector. Linnaeus even mentions India as the origin of the species. But he does also mention reports of a two-horned rhino from Africa. Later, when more became known about the distribution of rhinos, the term Rhinoceros bicornis was used broadly for all rhinos from Africa.
Genetic variation within the Black Rhino remains a point of discussion among scientists—as many as seven or eight subspecies have been mooted. For this review, however, the scheme used by the IUCN has been followed which recognizes three surviving subspecies and two as extinct:
- the Southern Black Rhino, sometimes historically referred to as the Cape Rhino (B. b. bicornis)
- the Eastern Black Rhino (B. b. michaeli)
- the South-central Black Rhino (B. b. minor)
- the Northeastern Black Rhino (B. b. brucii)
- the Western Black Rhino (B. b. longipes)—longipes comes from the Latin longus meaning long and pes meaning foot…a reference to the bone structure of the foot and one of a number of the subspecies’ anatomical deferences from other subspecies.
INDIAN RHINO
The scientific name for the Indian Rhino, Rhinoceros unicornis, is made up from a mix of Greek and Latin words…the Greek rhin meaning nose and keras meaning horn give us Rhinoceros, while the Latin uni meaning one or single and cornu meaning horn give us unicornis. Carl Linnaeus was the first to describe the species for science from a specimen sent to him in 1758. Since that time many alternative scientific names have been proffered, but all are regarded as synonyms for Rhinoceros unicornis which remains current.
JAVAN RHINO
The Javan Rhino (Rhinoceros sondaicus) is the only other rhino species to share the genus Rhinoceros with the Indian Rhino…sondaicus derives from Sunda, a region of the great Malaysia Archipelago that includes Java, Sumatra, Borneo and many smaller islands.
Of the three distinct subspecies, only one survives:
- the Indonesian Javan Rhino (R. s. sondaicus)
- the Vietnamese Javan Rhino (R. s. annamiticus)…annamiticus derives from the Annamite Mountains of eastern Indochina. It is extinct.
- the Indian Javan Rhino (R. s. inermis)…inermis means unarmed, a reference to the characteristically small horn of the male rhino and the complete absence of a horn in females.
SUMATRAN RHINO
The name of the Sumatran Rhino, Dicerorhinus sumatrensis, derives from the Greek words di meaning two, cero meaning horn and, rhinos meaning nose. The suffix sumatrensis is a literal reference to the island of Sumatra from where the rhinos first became known to European scientists. The scientific name for the genus Dicerorhinus was first suggested by the German zoologist Wilhelm Gloger in 1841, but there were a number of other contenders and it wasn’t until 1977 that the name was finally fixed.
Three subspecies are recognized:
- the Western Sumatran Rhino (D. s. sumatrensis) is extinct. The rhinos in Peninsular Malaysia were once known as D. s. niger, but were later recognized to be a synonym of D. s. sumatrensis.
- the Eastern Sumatran Rhino (D. s. harrissoni) was named in honor of the colorful polymath Major Tom Harnett Harrisson, DSO OBE (sometimes referred to as the ‘Barefoot Anthropologist’) who spent much of his life in Borneo.
- the Northern Sumatran Rhino (D. s. lasiotis)—The name lasiotis is derived from the Greek for hairy-ears. Later studies showed that their ear-hair was not longer than other Sumatran Rhinos, but D. s. lasiotis remained a subspecies because it was significantly larger than the other subspecies.

WHITE RHINO
Also known as the Square-lipped Rhino—the northern subspecies has sometimes been referred to as the Nile Rhino. Other European language names include: Rhinocéros Blanc (French), Rinoceronte Blanco (Spanish), Weißes Nashorn (German),and Witrenoster (Afrikaans).
African names include more than 50: Click here to see them.
BLACK RHINO
Also known as the Hook-lipped Rhino. Other European language names include: Rhinocéros noir (French), Rinoceronte Negro (Spanish), Schwarzes Nashorn (German), and Swartrenoster (Afrikaans)
African names include at least 175: Click here to see them.
INDIAN RHINO
Also widely known as the Greater One-horned Rhino, Great Indian Rhino, and Nepalese Rhino.
Other European language names include: Rhinocéros unicorne de l’Inde (French), Rinoceronte Unicornio Índico (Spanish), and Indisches Nashorn or Panzernashorn (German)
Asian names include at least 12: Click here to see them.
JAVAN RHINO
Also known as the Lesser One-horned Rhino. Other European language names include: Rhinocéros de la Sonde (French), Rinoceronte de Java (Spanish), and Java-Nashorn (German)
Asian names include nearly 100: Click here to see them.
SUMATRAN RHINO
Also know as the Hairy Rhino, the Asian Two-horned Rhino. The Bornean subspecies is sometimes referred to as the Bornean Rhino. Other European language names include: Rhinocéros de Sumatra (French), Rinoceronte de Sumatra (Spanish), Sumatra-Nashorn (German)
Asian names include some 86 – Click here to see them.
WHITE RHINOS—ONE SPECIES…OR TWO?
Things are never quite settled in science—it’s all part of an ongoing, rigorous process of questioning and challenging what we know, and then changing when the evidence suggests we should. In respect of the White Rhino, there has been an ongoing dispute regarding its taxonomic classification. Presently the Northern and Southern White Rhinos are described by the IUCN as subspecies of Ceratotherium simum. But it has been argued that the differences between the two and other factors are sufficient for them to be recognized as two separate species altogether.

- The Northern White Rhino is smaller and lighter than its Southern counterpart—males weigh 3,000–3,500 pounds (1,400–1,600 kilograms) as opposed to 4,400–5,300 pounds (2,000–2,400 kilograms).
- The Northern Rhino lacks the prominent shoulder hump so defining of the Southern subspecies.
- The skull of the Northern Rhino is flatter compared with the concave profile of its Southern cousin.
- The Northern Rhino has more body hair.
- The front horn of the Southern Rhino is generally longer than that of the Northern subspecies.
- The Northern Rhino lacks the groove between the ribs that is so characteristic of the Southern Rhino.

The late Colin Groves (one of the world’s leading anthropologists and taxonomists) thought so, and in 2010 he and his co-workers published a paper putting forward the case for two species. The Groves paper, however, has been criticized by some and its proposal has not been universally accepted. A more detailed outline of this debate can be found in the IUCN Red Data List.
It has also been argued that the “separate species” proposition is somewhat academic given the parlous conservation status of the Northern White Rhino: it is extinct in the wild and the only remaining captive male died in 2018. And so the entire global population of Northern White Rhinos has been reduced to two elderly females that reside in the Ol Pejeta Conservancy in Kenya, and samples of stored male semen and DNA.
In vitro fertilization is the only possible route for saving the subspecies, but given the age of the two females it would probably require their IV fertilized eggs being placed in a surrogate Southern White female. Possibly the semen could also be used to impregnate a South White Rhino female, thus preserving something of the gene pool. IVF techniques may be too late to save the Northern White Rhino, but improved technology could play a vital role in the future of the Javan and Sumatran Rhinos and many other endangered species as well.
Find out more about IVF in “Protecting Rhinos”y/03/11 17:58:11 a3/p3