Blue whales are bigger than big! Not only are blue whales the biggest mammals, but they're also the biggest vertebrates in the entire world. Bigger than any mammal we know of on dry land, young biologists will love learning how blue whales survive in the open ocean. This massive mammal will fascinate young readers and encourage even the most reluctant students to read on. With photographs of this mammal in the wild, young biologists will love discovering more about blue whales!