Rhinoceros | OtterKnow Kids Encyclopedia

Introduction

The rhinoceros, or rhino for short, is one of the largest and most powerful animals on Earth. Rhinoceroses are part of a group of animals known as megafauna, which means they are among the biggest creatures alive today. There are five living species of rhino spread across Africa and Asia, and all of them are in danger of disappearing forever. Despite their tough appearance, rhinos are plant-eaters that mostly want to be left alone, and they play an important role in the ecosystems where they live.

The Five Species

Two rhinoceros species live in Africa: the white rhino and the black rhino. The other three species live in Asia: the Indian (or greater one-horned) rhino, the Javan rhino, and the Sumatran rhino. White and black rhinos both live in grasslands and savannas, though the black rhino also inhabits scrubby bushland. Indian rhinos are found in the grasslands and swamps of northern India and Nepal, while Javan and Sumatran rhinos live in the dense tropical forests of Southeast Asia. The Sumatran rhino is the smallest species, and it is also the most ancient, with close ties to the woolly rhinoceros that lived during the Ice Age.

Size and Appearance

The white rhinoceros is the largest of the five species and the second-heaviest land animal after the elephant. Male white rhinos can weigh over 2,300 kilograms (about 5,000 pounds) and stand nearly 1.9 meters (over 6 feet) tall at the shoulder. All rhinos have thick, grayish skin that can be 1.5 to 5 centimeters thick, almost like natural armor. Despite its thickness, their skin is actually quite sensitive to sunburn and insect bites, which is why rhinos love to wallow in mud. The mud acts as a natural sunscreen and bug repellent.

Horns

One of the most recognizable features of a rhinoceros is its horn. White, black, and Sumatran rhinos have two horns, while Indian and Javan rhinos have just one. Rhino horns are made of keratin, the same protein found in human fingernails and hair. Unlike the horns of cattle or antelope, which have a bony core, rhino horns are solid keratin all the way through. A white rhino’s front horn can grow to an average of 60 centimeters (about 2 feet) long, though some individuals have had horns reaching well over a meter. Rhinos use their horns for defense, digging for water, and breaking branches while feeding.

Diet and Feeding

All rhinoceroses are herbivores, but different species eat in different ways. The white rhino has a wide, flat mouth designed for grazing on short grasses, which is why it spends most of its time with its head down on the open plains. The black rhino, on the other hand, has a pointed, hook-shaped upper lip that helps it pluck leaves, twigs, and fruit from bushes and small trees. Asian rhinos eat a mix of grasses and browse, and Sumatran rhinos are known to push over small trees to reach the tender leaves at the top. An adult rhino can eat 50 to 60 kilograms (about 100 to 130 pounds) of food each day.

Senses and Behavior

Rhinos have very poor eyesight and often cannot see a motionless person standing just 30 meters (about 100 feet) away. To make up for this, they have excellent hearing and an incredible sense of smell. In fact, the part of a rhino’s brain devoted to smell is larger than all the other parts of its brain combined. Rhinos are mostly solitary animals, especially males, though white rhinos can be somewhat social and may form small groups of up to 14 individuals. When a rhino feels threatened, it may charge at speeds of up to 50 kilometers per hour (about 30 miles per hour), making it surprisingly fast for such a heavy animal.

Baby Rhinos

A mother rhino carries her baby for about 15 to 16 months before giving birth, one of the longest pregnancies in the animal kingdom. Newborn calves can weigh between 40 and 65 kilograms (about 90 to 140 pounds) depending on the species, and they are able to stand and walk within an hour of being born. Calves stay close to their mothers for two to three years, learning where to find food and water. Mother rhinos are fiercely protective and will charge at any predator that comes too close to their young, including lions, hyenas, and even other rhinos.

Conservation Crisis

Rhinoceroses face one of the most serious conservation crises of any animal group. Three of the five species are listed as Critically Endangered by the International Union for Conservation of Nature (IUCN). The Javan rhino is one of the rarest large mammals on Earth, with only about 70 individuals surviving in a single national park in Indonesia. Poaching is the biggest threat to rhinos because their horns are illegally sold for large sums of money, even though the horns have no proven medical value. Conservation programs in Africa and Asia have made real progress, especially with the Indian rhino, whose population has grown from fewer than 200 in the early 1900s to over 4,000 today thanks to strict protection.

Lifespan and Role in Nature

Wild rhinoceroses typically live between 35 and 50 years, depending on the species. Throughout their long lives, rhinos shape the landscapes where they live. By grazing and browsing, they help control plant growth and keep grasslands open for other animals. Their wallowing holes fill with rainwater and become mini ponds that frogs, insects, and small mammals depend on. Protecting rhinos means protecting entire ecosystems and the countless other species that share their habitat.