Flippers. That makes you think of seals and sea lions. Is the answer to our riddle some kind of huge sea lion, you ask?
No. Unlike the sea lion, our mammal never crawls out of the water. Its flippers (pectorals) are very helpful to use for steering while it swims. Sometimes these enormous animals jump completely out of the water; with those long flippers swinging, they are quite a sight.
Of course, now you wonder how big these animals really are. The biggest ones grow to 55 feet (17 m) in length, or a bit more. The females are bigger than the males.
You are thinking hard. A mammal, yet it lives underwater…and it’s 55 feet long. Only one answer is possible. Yes, Wondernose, our mystery animal is a whale.
Now you must guess what kind of whale. Obviously it’s not the blue whale. Those monsters—the world’s largest animals—are up to 100 feet (30 m) long. However, our mystery whale is in the same group as the blues, because it is also a baleen whale. You will remember that all whales are in two groups, the toothed ones and the baleen ones.
Remember what baleen is? Yes, it’s that series of whalebone plates hanging down on either side of the whale’s mouth. The whale eats by gulping huge mouthfuls of water. When it forces the water back out through the baleen, the thousands of tiny creatures it enjoys for food will stay in its mouth. I never cease to find it interesting that an immense animal like the whale eats tiny plankton and krill—little crustaceans, some of which are as small as an inch or two long.
A lot of plankton is needed to feed a whale, though. A big whale will eat a ton of food in a day—a summer day, that is. The whale of our riddle tends not to eat much during the winter, instead living off its stored blubber.
Our whale covers many miles in a year’s time, spending the summer in cold waters and the winter in tropical waters.
Our mystery whale belongs to a subgroup called the rorquals. What these all have in common is the series of grooves on their undersides. The grooves enable them to open their mouths very, very wide.
But not quite as wide as the bowhead whale. The bowhead has the largest mouth of any animal—it is huge. But still, our whale can take in an enormous amount of sea water from which to strain its breakfast of plankton. Apparently these whales sometimes gulp in more than they’ve bargained for. One of them was found dead one day with half a dozen cormorants in its mouth and another one stuck in its throat. It seems the cormorants happened to be feeding on the same plankton when that whale took a gulp.
We’ve narrowed down our whale’s identity by putting it in the major group of baleens and the subgroup of rorquals. Now what hint shall I give you for this whale’s species name? I’ve already told you about its most distinctive feature—those extra-long flippers. But its name comes from a habit it has of humping its back whenever it takes a dive into the water.
Right, this is the humpback whale. If you were to look for a hump on its back, though, you wouldn’t find any. The back is as sleek as any whale’s. On the whole, though, humpbacks are chubbier and less streamlined than most whales. At different places on their bodies, humpbacks have wart-like growths, each of which has a hair growing from it. Yes, Wondernose! A whale with hair! But not very many. Those growths, or tubercles, are found mostly on the flippers and near the mouth.
Another factor contributing to the humpback’s less-than-sleek appearance is the fact that it’s often encrusted with barnacles and whale lice. It is thought that humpbacks sometimes leap high into the air to rid themselves of barnacles.
In their migrations, humpbacks tend to follow coastlines. Humpbacks are fun to watch. Not only do they leap clear of the water, but they also enjoy slapping the water with their big flippers and their tails.
