The hippopotamus, a herbivore, possesses one of the most powerful sets of teeth in the animal kingdom. This contrast between its plant-based diet and its dental weaponry is notable. The characteristics of these teeth define the hippo’s social structure and defense mechanisms and have also drawn them into the world of the ivory trade. Understanding their dental anatomy reveals a more complex animal than its appearance suggests.
The Anatomy of a Hippo’s Mouth
A hippo’s mouth contains a variety of teeth, but the most prominent are the lower canines and incisors, which form tusks. The canines, in particular, are capable of growing up to 1.5 feet (50 cm) in length. These tusks are composed of dentin and enamel, a material commonly referred to as “hippo ivory.”
A hippo’s tusks grow continuously throughout its life. This growth is paired with a natural sharpening mechanism. As the hippo closes its mouth, the long lower canines grind against the shorter upper canines, honing them into sharp, chisel-like points. This self-sharpening action ensures their weapons are always ready for use.
Further back in the hippo’s jaw are the molars. These broad, flat teeth are designed for grinding tough vegetation, the primary component of their diet. The powerful masseter muscles of the jaw enable the hippo to effectively crush coarse grasses and other plants between these molars, breaking them down for digestion.
The Purpose of a Hippo’s Teeth
The tusks of a hippopotamus are not for eating; instead, they are primarily tools for combat and communication. Hippos use their muscular lips to grasp and pull up grasses when they graze. The sharp canines and incisors are reserved for social interactions, particularly for disputes between males over territory and access to females. These fights can inflict deep, serious wounds.
A hippo’s “yawn” is not a sign of sleepiness but a threat display. By opening its mouth up to 150 degrees, a hippo reveals its tusks, showcasing their size and sharpness. This display serves as a warning to rivals and potential predators and a method to establish dominance without resorting to physical conflict.
Beyond territorial disputes, the teeth are also used for defense. While an adult hippo has few natural predators, crocodiles and lions may attempt to prey on calves. A mother hippo will use her tusks to defend her young from any perceived threat. The power of a hippo’s bite, combined with its tusks, makes it one of the most dangerous animals in Africa.
Hippo Teeth and the Ivory Trade
Hippo teeth have become a commodity in the global ivory trade, especially as international restrictions on elephant ivory have tightened. The dense, white dentin of hippo canines is valued and can be carved into decorative objects and jewelry. This demand has made hippos a target for poaching, contributing to a decline in their populations.
The trade in hippo ivory is regulated under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), but it is not subject to a complete international ban like the one on commercial elephant ivory trade. This has created a legal, regulated market that can be exploited for illegal activities. The difficulty in distinguishing legally sourced hippo ivory from illegally poached teeth presents a challenge for law enforcement and conservation agencies.
Uganda, for example, has experienced a decline in its hippo numbers, with the ivory trade being a primary driver. As long as there is demand, hippos will remain under threat. Conservation efforts are focused on disrupting trafficking networks, increasing patrols in hippo habitats, and pushing for stronger regulations to protect these animals.