The ocean, in its vastness, is home to some amazing animals—and some amazing myths. The sailors and explorers we studied in history class are famous for more than their voyages and discoveries. Their travels often came with tales of fantastic creatures, too strange to be true. This Halloween, we thought we’d revisit some of the ocean’s most famous mythical creatures. 

Mermaids

Mermaids have a long, complex mythology, appearing in everything from Homer to Hans Christen Anderson. As you’re probably aware, historians believe this legend originated with sailors who had a little too much salty sea air.

Imagine you’ve been at sea for several weeks with a diet consisting solely of hard tack and rum. Suddenly you spot a beautiful mermaid off the starboard bow! Slow down, captain… that’s probably just the rum talking. You’re really just looking at a manatee or a dugong.

Manatees and dugongs make up a group of animals known as the Sirenia, whose name is derived from the mythological women found in Greek mythology. Also known as sea cows, the Sirenia are aquatic mammals that spend their days grazing in seagrass beds. All four species of Sirenia are considered vulnerable under the IUCN Red List.

The Kraken

No creature was more feared by sailors than the kraken—a gigantic mythical beast said to be “round, flat, and full of arms, or branches,” that rises up from the sea to eat fish and fishermen alike. Its massive size is said to cause whirlpools capable of sinking ships, and its spreading muddy cloud to darken the water.

The inspiration behind the legend of the Kraken is most likely the giant squid, the largest of which was nearly 43 feet long. In addition to its eight arms, giant squid have two feeding tentacles tipped with suckers. They use these tentacles to catch prey and bring toward their sharp beaks. Little is known about the behavior of the giant squid, as very few have been seen alive. Most of what scientists know comes from the bodies of giant squid that wash ashore.

Unicorn

When most people think of unicorns, they don’t think of the ocean. However, in medieval times, it was commonly believed that narwhal tusks belonged to the legendary unicorn. Highly prized, these tusks supposedly contained magical powers.

In reality, a narwhal’s tusk is an enlarged tooth, usually found on males. Scientists aren’t positive what it’s used for, but have proposed theories from attracting mates, to more recently sensing the environment.