Elephants are the most famous tusked animals, but they share this trait with a surprising range of species, from walruses and narwhals to wild pigs and even certain deer. What unites them is a specific type of tooth: one that grows continuously throughout the animal’s life, powered by an open pulp cavity that keeps producing new material from the inside out. Unlike regular teeth, a true tusk starts with an enamel cap that wears away over time, leaving a structure made almost entirely of dentin coated in a thin layer of cementite. This is what distinguishes a tusk from, say, a rodent’s ever-growing incisors, which maintain their enamel edge permanently.
Elephants: Three Species, Different Tusks
All three living elephant species grow tusks, but there’s a key difference between the African and Asian lineages. Both male and female African elephants grow tusks, while only some male Asian elephants do. Female Asian elephants either lack tusks entirely or grow small, barely visible ones called tushes.
African savanna elephants, the largest land animals alive, carry tusks that curve outward in a wide arc. African forest elephants, a smaller and more elusive species, have straighter tusks that point downward. In terms of sheer size, the record tusk from an African bush elephant measured 345 cm (about 11.3 feet) along its curve and weighed 117 kg (258 pounds). A pair of exceptionally large tusks displayed in the British Museum in London weigh 97 and 102 kg each. Elephants use their tusks for digging, stripping bark, moving obstacles, and fighting.
Tusks are essentially modified incisor teeth in elephants, and they’re composed of roughly 59% mineral and 34% protein by weight. This is the material we call ivory, and it’s nearly identical in composition between modern elephants and their extinct relatives, the woolly mammoths.
Walruses
Both male and female walruses grow prominent tusks, which are elongated upper canine teeth. Males typically reach about 100 cm (39 inches) in length, while females average around 80 cm (31.5 inches). Walruses rely on their tusks primarily for hauling their massive bodies out of the water onto ice floes and rocky shorelines, digging the points into the surface for leverage. Tusks also play a major role in establishing social rank: larger tusks generally signal dominance, and males use them in confrontations during breeding season.
Narwhals: A Tusk That Can Sense
The narwhal’s single spiraling tusk, which can reach lengths of nearly 10 feet, is actually a left upper canine tooth that erupts through the lip and extends forward from the head. It’s one of the most unusual structures in the animal kingdom, and not just for its appearance.
Research has confirmed that the narwhal tusk functions as a sensory organ. Seawater enters through porous channels in the outer cementum layer, travels through a network of tiny tubules running through the dentin, and reaches nerve-rich pulp tissue deep inside the tusk. Those nerves connect to the brain through the same cranial nerve pathway that carries facial sensation in other mammals. In experiments, narwhals showed significant changes in heart rate when researchers alternated high-salt and fresh water against the tusk surface, confirming that they can detect environmental changes through it. The tusk may help narwhals sense shifts in salinity, temperature, or water pressure as they navigate Arctic seas.
Hippopotamuses
Hippos grow two sets of continuously growing teeth that qualify as tusks: their lower canines and lower incisors. The canines are the more dramatic of the two, reaching up to 20 inches in length. These teeth are self-sharpening. The upper and lower canines grind against each other as the hippo opens and closes its mouth, honing the lower canines into formidable weapons. Hippo ivory is denser than elephant ivory and was historically carved for dentures and other purposes. Despite their herbivorous diet, hippos are among the most aggressive large animals in Africa, and their tusks are a primary reason they’re so dangerous in confrontations.
Wild Pigs and Warthogs
Several members of the pig family grow tusks, though they vary dramatically in shape and function. Warthogs are born with tusks and develop two pairs: the upper tusks curl upward and outward, while the lower tusks are shorter and sharper. Both warthogs and other wild pigs like the red river hog use their tusks alongside their snouts to root in the ground for food. Male warthogs also rely on fleshy pads (warts) on their faces to absorb blows during tusk-to-tusk combat over mates.
The most extreme tusks in the pig family belong to the babirusa, a species found on the Indonesian island of Sulawesi. A male babirusa’s lower canines grow upward past the jaw like conventional pig tusks, but its upper canines do something far stranger: they grow upward through the skin of the snout, piercing right through the top and curving back toward the forehead. The result looks more like a pair of horns or antlers than teeth. These upper tusks may help shield the face during fights, though they’re brittle enough that their defensive value is debated. If left unchecked by wear or breakage, the upper tusks can eventually curve far enough to approach the skull.
Tusked Deer
Not all tusked mammals are large or obviously dangerous. The Chinese water deer, now established in parts of England after escaping from wildlife parks, is a small deer whose males grow no antlers at all. Instead, they develop long, curved upper canine teeth that protrude about 7 cm (nearly 3 inches) below the lip. These tusk-like canines serve the same basic purpose antlers do in other deer species: males use them in territorial fights during the breeding season, slashing at rivals with surprisingly effective results. Muntjacs, another small deer, split the difference by growing both short antlers and small upper canine tusks.
Woolly Mammoths and Other Extinct Species
The largest tusks ever recorded belonged to woolly mammoths. The longest confirmed male mammoth tusk measured 380 cm (about 12.5 feet) along its outer curve, with a diameter of 18 cm at the base and a weight of 86 kg. Early 20th-century reports describe specimens up to 400 cm long and over 100 kg. Female mammoth tusks were considerably smaller, with the record at 247 cm and just under 20 kg.
Mammoth tusks had a more dramatic spiral than those of modern elephants. In adult males, the tips could curve inward until they nearly touched or even crossed each other. Some females carried straighter tusks. Tusks exceeding 350 cm and 80 kg were rare even among Siberian mammoths, suggesting that truly massive tusks were as exceptional then as they are in elephants today.
Mammoths weren’t the only extinct tusked animals. Dicynodonts, a group of mammal relatives that lived before the dinosaurs, were among the earliest animals to evolve true tusks. Research into their fossilized tooth tissue confirms they had the same hallmark features of modern tusks: continuous growth, an open pulp cavity, and dentin-dominated composition with enamel only at the tip during early development. This means the tusk as a biological strategy has been around for over 250 million years, reinvented independently by very different lineages.