Some scientists now believe that some sea creatures were once land animals that returned to the sea. Whales, for instance, are distant relatives of deer, and walruses are related to otters.

There are more than 500 species of shark worldwide, all but seven are listed as endangered or vulnerable species.

The evolutionary record shows snapping turtles have barely changed in 90 million years. They likely looked and hunted as they do today when dinosaurs were still around.

The Narwhal is a peculiar species of whale found in the Arctic with a long spiraling horn protruding from its head, which can reach up  to ten feet long. It is thought that Narwhals were one of the creatures that may have inspired myths of legendary unicorns.

Despite its name, however, a Narwhal’s horn is actually a gigantic tooth that grows from its mouth and through its skin.

Bowhead whales are some of the longest-lived sea creatures and can often live around 200 years.

In 2007, a gigantic 50-ton Bowhead whale was caught off the coast of Alaska, with a century-old harpoon embedded in its neck.