When you think of marine life, you probably think about scaly fish with gills, but there are a variety of aquatic mammals that breathe air. So hold your breath and dive into the marine mammals quiz! See more »

The walrus has many clever adaptations to help it survive and thrive in some of the harshest climates on Earth. You may not be the walrus, but test your knowledge of these toothy creatures in the walrus quiz anyway. See more »

Whether you're sleeping on a water bed or napping during a rainstorm, water has a calming effect. Walruses also make use of soothing waves, but why don't they drown when catching submerged shut-eye? See more »

Beluga, or White Whale, a toothed whale of the Arctic, related to the narwhal. The beluga reaches a length of 11 to 18 feet (3.4 to 5.5 m). See more »

Bottle-nosed dolphins have long had the image of being intelligent guardians of the sea who speak their own language, enjoy the company of humans, and have even saved shipwrecked sailors from certain doom by leading them to land. See more »

Dolphin, a toothed whale that is related to the porpoise. The dolphin has a long, streamlined body; some species have a prominent beaklike snout. See more »

Narwhal, a toothed whale found in arctic waters near Canada and Greenland. The male narwhal has a long, spiralled tusk. See more »

Porpoise, the smallest of the toothed whales. It resembles the dolphin, but is smaller, seldom more than six feet (1.8 m) long, and has a blunt muzzle instead of a pointed one. See more »

Seal, a meat-eating mammal found in all oceans of the world, but most abundant in Arctic and Antarctic waters. See more »

Baleen whales are some of the largest creatures in the world. In fact, the blue whale, a type of baleen whale, is the largest creature to have ever lived. It is hard to imagine a creature that is large enough to swallow a small school bus in one gulp. Take this quiz to learn more about baleen whales. See more »