Marine Monday: Narwhal - Oceana USA
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October 17, 2011

Marine Monday: Narwhal

Who doesn’t love the unicorns of the sea?

Narwhals, like dolphins and whales, are cetaceans, although they are found almost exclusively in the Arctic Ocean. Because narwhals spend so much time in icy waters, about a third of their weight is blubber to stay warm.

Narwhals are known for their unicorn-like tusk — which is actually a tooth! All narwhals have two teeth, but in most male narwhals, one of these teeth grows through the upper lip and can be as long as ten feet. Sometimes males will have two tusks or none, and occasionally females grow tusks.

Scientists aren’t quite sure why narwhals grow tusks. One idea is that males use them to prove their worth as mates and compete with other males. Another theory is that narwhals use their tusks to skewer food or mix up bottom sediments, but this doesn’t explain why female narwhals typically don’t have horns.

Just like human teeth, narwhal tusks contain blood vessels and sensory tissue—but on the outside of the tusk, so other scientists think they may be used to figure out where ice is forming, how salty water is, or what prey is nearby.

Narwhals eat squid, octopus, fish, and shellfish. Because they have only two teeth (and one usually can’t be used to chew), they usually swallow their food whole. They have also developed a special hunting technique that uses suction and water jets to pull fish and mollusks off the seafloor.

These mammals can live for as long as 50 years. They spend most of their time in small groups of less than ten narwhals, typically of only one gender, but these small groups can join forces in herds of hundreds.

Scientists believe there are about 80,000 narwhals in the Arctic right now, but are not sure whether these animals are thriving. In addition to subsistence hunting by Inuit for their skin and blubber, narwhals are also hunted for their horns. And climate change could cause serious disruptions to their lives, which are based around pack ice.

Learn more about narwhals and other fascinating sea animals at Oceana’s marine encyclopedia.