Are Hippos And Rhinos Related?

Hippos and rhinos are two of the largest land mammals on Earth today. At first glance, they seem about as different as two animals can be—the hippo spends most of its time submerged in water, its hairless hide keeping it cool and moist, while the rhino stays on dry land, protected from the baking sun by an armored hide.

But if you look a little closer, do these hefty herbivores have more in common than meets the eye? If you’re short on time, here’s a quick answer to your question: Despite some superficial similarities, hippos and rhinos are not closely related.

They belong to completely different mammalian orders that diverged over 50 million years ago.

In this comprehensive guide, we’ll look at the evolution, anatomy, behavior, and conservation status of hippos and rhinos. We’ll compare and contrast these unique species to find out where they overlap and where they differ.

By taking a deep dive into the hippo-rhino connection, we’ll uncover surprising insights about these ancient African megaherbivores—and learn why the answer to our question is not as straightforward as it may first appear.

The Evolutionary Origins of Hippos and Rhinos

When Hippos and Rhinos Diverged

Hippos and rhinos share a common ancestor from around 55 million years ago! That’s quite a long time ago. Their evolutionary lineages split off from each other in the late Paleocene or early Eocene period. Back then, the world was much warmer than it is today, with little ice at the poles.

Dense forests covered parts of Earth. Over time, these mammal relatives adapted to different ecological niches and evolved into the unique species we know today.

Hippos’ Closest Living Relatives

You might think hippos are giant pigs or hairless tapirs, but genetic analyses show hippos are actually the closest living relatives to whales! Hippos and whales share a semi-aquatic ancestor that lived around 60 million years ago. After they split, whales became fully aquatic and adapted to live in the ocean, while hippos stayed in freshwater habitats like rivers and lakes.

Though hippos can’t live in the ocean, they do share some traits with whales like being able to hold their breath underwater for long periods of time.

The Ancestry of Modern-Day Rhinos

Research indicates that rhinos are closely related to tapirs, horses, and zebras. They share a common ancestor from around 50 million years ago. There used to be many more rhino species roaming Earth, but today only five species remain – black rhino, white rhino, Indian rhino, Javan rhino, and Sumatran rhino.

Sadly, all five remaining rhino species are endangered due to poaching and habitat loss. Conservation efforts are working to protect these majestic creatures for future generations to enjoy.

Hippo and Rhino Anatomy in Comparison

Size and Weight

Hippos (Hippopotamus amphibius) range from 3,000 to 9,000 pounds with lengths up to 17 feet, making them some of the largest mammals after elephants and some species of whales. Rhinos have much more diverse sizes depending on species, with weights ranging from 1,700 to 7,000 pounds.

The white rhino is the second largest land mammal behind elephants at up to 6,000 pounds and lengths over 13 feet. In contrast, the Sumatran rhino is the smallest species under 5 feet long and less than 1,700 pounds.

Skin and Armor

Both hippos and rhinos have very thick skin to protect themselves. Hippos secrete their own sunscreen substance giving them extra protection. Rhinos have more external armor in the form of hardened keratin covering the skin in plates.

Sumatran rhinos have a dense covering of hair more similar to hippos. White rhinos have a softer mud wallow covering. The Indian one-horned rhino has the thickest skin folds of any land animal.

Skulls and Teeth

Hippos have very wide flat skulls and mouths for their mostly vegetarian diet, with large canine teeth still capable of biting crocodiles in half. Rhinos have much taller skulls to support their horns – up to 5 feet above their shoulders for the white rhino.

Their skulls allow muscles to power bites strong enough to twist off thick branches and tree trunks. Sumatran rhinos have simpler cusped teeth while white and black rhinos have wide ridged teeth adapted for grazing grasses.

Habitat and Behavior

Where Hippos and Rhinos Live

Hippos and rhinos inhabit vastly different habitats across Africa. Hippos are found primarily in swamps, lakes, and rivers, where they spend much of their time submerged in water to keep their skin moist and cool.

In contrast, rhinos prefer dry land and are found in savannas, grasslands, forests, and deserts. White and black rhinos browse on trees and shrubs, while the larger Indian and Sumatran rhinos graze on grasses.

Despite their differences, hippos and rhinos may occasionally cross paths and share resources when their habitats overlap near bodies of water.

Daily Life and Social Structures

The daily lives and social structures of hippos and rhinos have some interesting comparisons. Hippos are very social and live in pods of up to 30 individuals led by a dominant male. They are most active at night when they graze on land up to 6 miles from water.

During the day, hippos remain cool and protect their sensitive skin by wallowing in mud. In contrast, rhinos are solitary creatures that only interact with others to mate or females with calves. Outside of mating, adult rhinos aggressively protect their home ranges from intruders.

Both species are large herbivores that spend their day eating substantial amounts of grass, shrubs, leaves, and other vegetation to fuel their immense size.

A key difference is that hippos are capable of running at speeds over 20 mph for short bursts, whereas rhinos have poor eyesight and max out around 35 mph. Slow moving compared to hippos, rhinos make up for it with thick protective skin and large horns capable of inflicting serious injury.

Reproduction and Parenting

Hippos and rhinos share some similarities when it comes to reproduction and raising young. After long gestation periods of 7-9 months for hippos and 15-16 months for rhinos, single calves are born. Baby hippos weigh 50-110 pounds at birth, while newborn rhinos are 60-140 pounds.

In both species, mothers are extremely protective of their young and may become aggressive toward intruders. For the first several months, calves continue to nurse and stick close to their mothers for protection. Around 2 years old, young hippos and rhinos are ready to strike out on their own.

A key difference is that female hippos reach sexual maturity earlier at 5-6 years compared to rhinos which mature between 5-7 years. Additionally, dominant male hippos mate with multiple females in the pod.

Rhinos are polygynous as well, but males space themselves out instead of consolidating territories.

Threats and Conservation

Hippo and Rhino Population Trends

Over the past decade, hippo and rhino populations have declined sharply across Africa due to poaching and habitat loss. According to the latest IUCN Red List assessments, the common hippopotamus is now classified as Vulnerable, with numbers decreasing by 7-20% over the last 10 years.

Black and white rhino species have suffered even steeper drops, with black rhino numbers falling by over 97% since the 1960s.

A recent WWF report found that from 1970 to 2012, hippo numbers declined by between 28-45%. This is largely attributed to poaching and global warming drying up their river habitats. In contrast, dedicated conservation efforts have helped southern white rhino numbers increase from less than 100 to over 20,000 today through protected areas and reintroduction programs in countries like South Africa. However, the northern white rhino subspecies has been decimated and is functionally extinct, with only two aging females remaining.

Poaching Crisis

The increase in illegal poaching over the past 15 years has had a devastating impact on rhino and hippo populations. Impoverished local communities have been exploited by sophisticated international criminal poaching networks to kill these animals for their horns and ivory tusks.

South Africa holds nearly 80% of the world’s remaining rhinos and has been hit the hardest by the recent poaching crisis. Over 9,000 rhinos have been killed in South Africa since 2008. A record 1,028 rhinos were poached there in 2017 alone.

And the crisis is only getting worse – poaching numbers have increased by over 9,000% in the past decade. At this rate, conservation groups warn that deaths are outpacing births and rhinos could be wiped out in the wild within 20 years.

The story is similar for hippos. A recent surge in demand for hippo teeth and ivory has led to intense hunting pressures. Herds across Sub-Saharan Africa are being decimated by local and international poaching syndicates.

Cote d’Ivoire’s hippo population plummeted by 95% over the past 30 years due to poaching according to a study in Biological Conservation.

Protecting These Species for the Future

Conservationists have proposed a number of initiatives to protect rhino and hippo populations from extinction:

• Increased funding for on-the-ground monitoring and security forces to prevent illegal poaching.
• Strengthening legal penalties for wildlife crimes to deter poachers and traffickers.
• Raising awareness to reduce consumer demand for rhino horn and hippo ivory, particularly in Asia.
• Community engagement programs that provide local people sustainable economic alternatives to poaching.
• Continued captive breeding and reintroduction efforts to boost rhino numbers.
• Additional protected habitats with suitable water resources where hippos and rhinos can thrive.

Saving these ancient mega-herbivores is critical for maintaining healthy African ecosystems and biodiversity. If poaching and habitat loss continues unchecked, conservation groups warn these iconic species could face extinction in mere decades.

Concerted local and global action is urgently needed to fund on-the-ground anti-poaching units, curb consumer demand, and protect dwindling hippo and rhino populations.

Conclusion

Although they occupy similar ecological niches, hippos and rhinos took very different evolutionary paths to get there. Their shared features—enormous size, herbivorous diets, semiaquatic lifestyles for some species—are a case of convergent evolution rather than close relation.

While threats from poaching and habitat loss impact both species, tailored conservation plans are needed that address the unique needs of hippos and rhinos.

Tracing the ancestral origins, evolutionary branches and modern traits of these captivating creatures has uncovered some surprising facts. Who would have guessed that the hippo shares a closer bond with whales than rhinos? Or that the miniature Sumatran rhino once roamed snowy Tibetan mountaintops?

Though distantly related, hippos and rhinos remain intertwined in human lore—and in the urgent work to secure their futures.