Why can fights between male hippopotamuses be deadly despite their thick skin?

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A hippopotamus stands at the edge of a watering hole, with several other hippos partially submerged in the water, surrounded by green vegetation in Botswana, Africa. — hippopotamus The word *hippopotamus* is Greek for “river horse,” which reflects their behavior: they are often seen basking on the banks or sleeping in the waters of rivers, lakes, and swamps across Africa. They favor shallow areas where they can sleep half-submerged, though these places can become quite crowded—as many as 150 hippos may use one pool in the dry season.

Fights between male hippopotamuses can be deadly because of the specialized weaponry they use during combat. While hippos possess thick skin—measuring approximately 5 cm (2 inches) on their flanks—this protection is often insufficient against the force and design of their teeth.1

During territorial disputes, males engage in combat by slashing upward at each other’s flanks using their lower canines and incisors. These teeth are exceptionally sharp, continuously growing, and can exceed 30 cm (12 inches) in length. Because these weapons are designed to inflict deep, penetrating wounds, they can bypass the defensive benefits of the hippo's hide, leading to fatal injuries despite the animal's robust physical build.123