Today’s Wonder of the Day was inspired by Kai. Kai Wonders, “what are on gray whales skin?” Thanks for WONDERing with us, Kai!

If you love sea creatures, you're probably fascinated by whales. These massive swimmers amaze us with their size and graceful moves. Whales aren't like other fish, though.

In fact, they're not fish at all! You may already know that whales are mammals. Like dolphins and porpoises, whales are aquatic mammals that share some common characteristics with other mammals, like humans.

For example, mammals are warm-blooded and they breathe oxygen from the air. They also give birth to live young and have hair.

If you're thinking, “Hmm…I've never seen a hairy whale before," you're not alone. Many people don't realize that whales have hair. After all, you never see a whale with a comb, do you?

Since whales aren't furry, you're probably WONDERing where they have hair. If you've ever seen a whale up close, you've probably noticed that their skin seems rather smooth and not at all hairy.

Of the over 80 species of whales in the world, only a few have visible hair. Many whales have hair on their bodies before they're born, but it often goes away shortly after birth.

A few whales have visible hair as adults. For example, the humpback whale has unique bumps on its head. The bumps, which are the size of golf balls, are called tubercles and they contain hair follicles.

Right whales have hair on their chins and upper jaws. Bowhead whales often have hair on their lips, chins, snouts and blowholes. Since whales don't need hair to keep warm (they have blubber for that!), scientists believe whale hair may serve another purpose, such as sensing things around them or communicating a need to nurse in their young.

Hair isn't the only thing that can make whale skin bumpy from time to time, though. Normally-smooth whale skin can become bumpy from scratches caused by interactions with other marine animals while feeding.

Marine parasites can also cause skin bumps and discoloration in whales. For example, whales are often seen with whale lice and barnacles attached to their skin. Both whale lice and barnacles are skin parasites. Whale lice are related to skeleton shrimp, while barnacles are related to crabs and lobsters.

If whales rub up against something that removes these creatures, scars on their skin are often left behind. That's why some whales have a spotted or “mottled" look to their skin. As if these problems weren't enough, scientists now also believe it's possible for whales to get sunburned. Due to ozone depletion, whales are being exposed to the sun's harmful ultraviolet rays when they surface to breathe, leading to sunburn and other skin problems!

Wonder What's Next?

Tomorrow’s Wonder of the Day is as light as…well…you’ll see…