With their giant bodies and aggressive nature, it’s easy to assume hippos are carnivorous beasts. But are hippos really meat eaters? The answer may surprise you.
If you’re short on time, here’s the quick answer: Despite their intimidating size and disposition, hippos are actually herbivores that mostly eat grass and aquatic vegetation.
In this comprehensive article, we’ll dive deep into the dietary habits of hippos and explore what these river giants like to feast on. You’ll learn about the unique biology that allows them to thrive on plants, why meat is rarely (if ever) on the menu, and how their grazing and pooping impacts the ecosystems they inhabit.
Hippos Have Unique Adaptations for a Herbivorous Lifestyle
Largeomachy Allows Them to Digest Fibrous Plant Matter
As obligate herbivores, hippos have evolved specialized digestive systems to break down tough plant fibers. Their stomachs comprise three chambers, allowing for an extended digestion process known as hindgut fermentation (Smithsonian’s National Zoo & Conservation Biology Institute, 2023).
This largeomachy gives bacteria extra time to help hippos utilize grasses and other rough vegetation.
With lengths up to 30 feet, their intestinal tracts are exceptionally long compared to other ungulates. Their colon alone can reach a whopping 10 feet long in mature adults (San Diego Zoo Wildlife Alliance, 2023).
This expanded capacity supports microbial fermentation of cellulose and hemicellulose – structural materials found in plant cell walls.
Wide Flat Teeth are Ideal for Grinding Grasses and Aquatic Plants
Hippos sport impressive sets of broad, flat teeth that are continuously replaced throughout their lives. They use these specialized chompers to shear and grind tough vegetation (African Wildlife Foundation, 2023).
Their wide jaws and large teeth give them an advantage in consuming fibrous grasses, reeds, and other plants found near inland waters.
An adult hippo’s mouth contains up to 44 teeth at a time, both in their upper and lower jaws. However, they do not use their teeth to chew food. Instead, hippos violently clamp down on plants to shear them and swallow the matter in large chunks.
Later, the food is further broken down through digestion and microbial fermentation (San Diego Zoo Wildlife Alliance, 2023).
Salivary Glands Produce Mucus That Coats Food for Easier Swallowing
To aid the swallowing process of poorly chewed fodder, hippos rely on their prolific salivary glands. These produce a thick, mucus-like substance that envelops the sheared plant material. This slippery coating allows the coarse chunks to slide down their throats more easily (Smithsonian’s National Zoo & Conservation Biology Institute, 2023).
Additionally, components within hippo saliva may supplement microbial digestion within their specialized digestive tracts. Researchers have identified bacteria within hippo spit that produce enzymes capable of breaking down plant polysaccharides (SANBI, 2021).
However, further studies are needed to better understand the relationship between hippo saliva and digestion.
Grasses and Aquatic Vegetation Form the Bulk of a Hippo’s Diet
Graze on Land at Night, Feasting on Grasses and Herbs
Under the cloak of darkness, hippos emerge from the water to graze on land. These hefty herbivores spend around 6 hours per night consuming their own body weight in grasses and herbs. Hippos prefer short grasses like Bermuda grass and ryegrass, and nibble on a variety of herbs including wild sorrel.
With their huge barrel-shaped bodies and flat muzzles, hippos can mow down incredible amounts of vegetation each night. Their nightly feasting helps keep grasslands healthy by preventing overgrowth.
Although hippos graze mostly on land at night, they still need to be wary of predators like lions, hyenas, and crocodiles. To reduce risks, hippos usually don’t wander more than a few miles inland to feed.
Hippos may also choose resting spots with easy access to water in case they need to make a quick escape.
Feed Underwater During the Day, Choosing Aquatic Plants
When the sun rises, hippos retreat to the water for protection from heat and sunburn. But they don’t stop eating! Hippos can forage on aquatic plants while completely submerged, thanks to their ability to close their ears and nostrils.
Common menu items include water lilies, lotus, and Vallisneria grass.
Hippos can hold their breath underwater for 5-6 minutes while feeding. Their eyes, ears, and nostrils are located high on their head and can remain above the water line even when the rest of the body is submerged.
Powerful jaws allow hippos to tear aquatic plants right out of muddy lake bottoms if needed.
Fruit and Crops are Occasionally Eaten When Available
Though grasses and aquatic plants constitute >90% of their diet, hippos are opportunistic feeders. When available, they will supplement their diet with fallen fruits from trees near rivers. Papayas, mangoes, and figs are occasional hippo treats.
Banana plants are another sought-after snack when hippos encounter them.
In agricultural areas, hippos sometimes venture out of the water at night to raid cornfields, sugar plantations, or orchards. Though their main staples are grasses and aquatic plants, hippos don’t pass up an easy meal from a tasty fruit tree or farm field.
Meat is Not Typically Part of a Hippo’s Natural Diet
Stomach Acid and Digestive System are Not Adapted for Meat
Hippos have a digestive system designed to break down plants, not meat. Their stomach acid is weaker compared to carnivores, at a pH of around 4.5 vs 2-3 for lions and hyenas. This means hippos cannot properly digest animal proteins. Hippos also lack some enzymes carnivores produce to process meat.
So while hippos have been documented eating meat on occasion, their bodies are not well equipped to make it a regular part of their diet.
They Lack the Hunting Instincts and Weapons of Carnivores
Unlike predators like crocodiles and lions, hippos do not have sharp teeth and claws for hunting prey. Their large, wide molars are ideal for grinding up vegetation, not tearing flesh. And while hippos can be very aggressive, they lack the predatory instincts that drive carnivores to relentlessly hunt for food.
So a hippo is highly unlikely to actively hunt down an animal to eat it.
Rare Cases of Carnivory are Due to Stress or Unnatural Conditions
There are a few documented cases of hippos eating meat, but these incidents almost always involve stressed or unhealthy hippos in unnatural captive environments. For example, in the early 1900s, a hippo named Billy at the Manchester Zoo became stressed after being antagonized by visitors.
Billy attacked and ate one of his ox companions – likely due to this severe stress.
Other incidents involve malnourished hippos or those with dietary deficiencies resorting to non-plant food sources out of desperation. But for a healthy hippo living naturally alongside herbivorous animals, meat does not factor into their diet.
The Hippo’s Diet Shapes the Ecosystems They Inhabit
Grazing Helps Maintain Grasslands and Prevents Overgrowth
Hippos are voracious grazers, consuming up to 150 pounds of grass each night. This helps maintain the grasslands and prevents overgrowth in the areas they inhabit (1). Their grazing habits create pathways through dense vegetation, allowing other smaller animals access to grazing areas.
The hippo’s mighty jaws and large teeth are perfectly adapted to their vegetarian diet.
Feces Spread Nutrients and Provide Food for Fish
Amazingly, the hippo’s hefty dung deposits also play a crucial role in their ecosystem (2). Their feces are rich in nutrients from the vegetation they consume, acting as fertilizer that enriches the soil and water. This helps stimulate plant growth.
Fish, insects, and other aquatic life feed on the nutritious hippo poop as well!
Overgrazing Can Also Damage Habitats if Populations Become Too Large
While hippos shape their habitats in many positive ways, they can also damage ecosystems if their populations become overly abundant. Large herds of hippos can potentially overgraze an area, depleting the food sources on which many species rely.
Maintaining balanced hippo numbers through conservation efforts is key to ensuring their grazing habits remain beneficial.
Conclusion
Despite appearances, the hippo is far from being a ferocious carnivore. Their adaptations, behaviors and preferences clearly show they thrive best on a vegetarian diet. Yet these hefty herbivores are still capable of being extremely dangerous due to their size and defensive nature.
Understanding the hippo’s true dietary habits provides insights into their ecological roles as massive grazers and spreaders of nutrients. So rest assured – if you encounter a hippo in the wild, there’s no need to run away as if you were prey.
Just give them plenty of space to continue happily feasting on plants in peace!
