Why do some whales not have teeth and why do whales have holes?

Javon Combs and Harrison Poh
Mrs. Parten's first grade class
Wrights Mill Road Elementary, Auburn

Dear Javon and Harrison,

Wouldn't it be great to have your nose on the back your head while you swim? Then you could take a breath while still looking down underwater. That essentially is what whales do. The hole on top of their head acts like a snorkel tube. Even though they live in the ocean, whales are mammals just like us and need to breathe air. And for a really big animal like a whale, sticking the whole mouth out of water to breathe would be pretty hard. So whales have developed noses on top of their heads, instead of the middle of their faces. Whales have even lost the second nostril, and retained only one so that they can come up for air while still keeping almost their whole body underwater. Dolphins do the same thing.

Whales can be divided into the toothed whales (killer whales Orca, sperm whales) and the baleen whales (humpback and blue whales, etc.). The toothed whales attack and eat giant squids, fishes, and in the case of Orcas, even other whales. The baleen whales don't need large teeth, because they eat some of the smallest animals in the ocean: krill. Krill are tiny shrimp-like animals that float in big groups in the sea, grazing on microscopic algal plants. Krill are an important base of the oceanic food chain since they provide food for so many marine predators such as penguins and seals.

Baleen is like a large, flexible fine-tooth comb. The whale swims through a group of krill and takes a big gulp of seawater. It then squeezes the seawater out between the strands of its baleen comb and krill get caught inside. The whale licks all that yummy krill off the inside of its baleen comb and has a feast. Kind of like pasta getting caught inside a colander when the water drains through. Some whales even dig for tasty tidbits on the ocean floor, and create huge pits by taking a big gulp of sand. They strain the fine sand through their baleen and capture all the tasty animals that live in the sand. You can tell where a whale has been feeding by the giant "footprints" they leave in the sandy bottom from straining out the animals and feeding on them.

Isn't it funny that the largest animals on earth eat some of the smallest animals? You would think a big whale would starve doing that. But each whale eats a LOT of krill, about 1-2 tons per meal. Krill are so abundant in the world's oceans (some scientists estimate that they are among the most common of marine animals), that even giant whales can satisfy their appetite by consuming them. One reason why baleen whales become so large is that they eat near the bottom of the food chain. That is, they eat the herbivorous krill, which in turn eat marine plants. So, baleen whales are only one step removed from plants in the food chain.

In contrast, the toothed whales are what we call top carnivores. They eat squids and other marine mammals, which in turn are prey on other animals. Because energy is lost at each level of the food chain, and the prey of toothed whales are less common than are krill, so the toothed whales tend reach smaller body sizes than do the baleen whales.

Thanks for your question,
Aubie and Dr. Chadwick