Narwhal

The narwhal is a chunky Arctic whale with no dorsal fin, just a shallow ridge on its back. Males grow a spectacular spiral tusk up to 3 meters long—actually an overgrown tooth. These whales dive deep in icy waters and sometimes hang out with their beluga whale cousins.

• Males have a spiral tusk that's actually an extra-long left canine tooth.
• Their necks have special joints to help them twist through icy water.
• They share parts of the Arctic with belugas and can interbreed with them.