Narwhals

That famous horn is actually a tooth. The defining feature of a narwhal is its massive, spiraling tusk, but it is not a horn at all. It is an enlarged canine tooth that pierces right through the whale’s upper lip.

Their tusks are packed with nerves. Rather than being a hard, dead weapon, a narwhal tusk is a highly sensitive sensory organ. It contains up to 10 million nerve endings that help the whale detect changes in water temperature, pressure, and salt levels.

Mostly males have the tusks. While almost all male narwhals develop the signature tusk, only about 15 percent of females grow one. In very rare cases, a male might even grow two tusks at the same time.

They change color as they get older. You can usually guess a narwhal’s age just by looking at its skin. Babies are born a dark blue-gray, juveniles turn a mottled blue-black, and older adults eventually become almost entirely white.

They are champion free divers. Narwhals regularly dive deeper than a mile into the pitch-black ocean to hunt for food. They can hold their breath for a staggering 25 minutes before surfacing for air.

They do not have teeth in their mouths. Aside from the giant tusk, narwhals are virtually toothless. Instead of chewing their prey, they swim close to a tasty fish or squid and use a powerful suction force to swallow it completely whole.

They never leave the Arctic. While many other whale species migrate down to warmer tropical waters during the winter, narwhals live in the freezing Arctic Circle all year long.

Sea ice is their favorite hiding spot. To avoid hungry predators like killer whales, narwhals use thick, floating sea ice as a natural shield. They find tiny cracks in the ice just wide enough to poke their heads out and take a breath.

They love hanging out in massive groups. A narwhal family group is called a pod, and they usually contain around 15 to 20 individuals. However, during the summer migration, hundreds or even thousands of narwhals will join together to form gigantic super pods.

Their name has a slightly spooky origin. The word narwhal comes from the Old Norse word for corpse. Ancient sailors thought the whale’s mottled gray skin looked exactly like the skin of a drowned sailor.

Half of their body is pure fat. To survive in water that hovers around the freezing point, narwhals are incredibly well insulated. Their blubber is several inches thick and makes up about 50 percent of their entire body weight.

They are surprisingly chatty. Even though they live in dark, icy waters, narwhals stay constantly connected with their pods. They communicate using a complex series of high-pitched clicks, squeaks, and whistles.

They are built to withstand immense pressure. When diving thousands of feet below the surface, the ocean pressure is intense. Narwhals have compressible rib cages that can safely squeeze together as they dive deeper, protecting their internal organs.

They are closely related to beluga whales. Narwhals and the pure-white beluga whales are the only two living members of the Monodontidae family. Both species lack a dorsal fin, which helps them swim smoothly right under the thick sheets of ice.

Their tusks inspired medieval myths. Hundreds of years ago, Viking traders would find narwhal tusks washed up on beaches and sell them to European royals for their weight in gold, claiming they were the magical horns of actual land unicorns.