Extreme Animals: The Toughest Creatures on Earth, by Nicola Davies, illustrated by Neal Layton (2006) is one of the best kid's non-fiction books I've ever read. Heck, even thought it's ostensibly a kid's book, this 61 page fact-filled, well-written, amusingly illustrated book would make a great present for the curious adult.
"We humans are such a bunch of wimps!" the book begins. "We can't stand the cold, we can't stand the heat, we can't live without food, or water, and just a few minutes without air is enough to finish us off." But there are creatures out there much, much tougher--an amazing assortment of living things who survive incredibly hostile environments. Did you know, for example, that polar bear fur is so marvellously effective at keeping warm air in that a heat-seeking mission to find the bears only glimpsed the occasional nose? Or that if you put a sponge in a blender, and then pour the glop back in the ocean, it can reassemble itself back into a living creature?
The explanations for such wondrous phenomena are clear and to the point, with helpful, and funny, illustrations that underline and clarify. Each section is one or two rather densely written pages long, sufficient for explanation, while not to long to be overwhelming. The vocabulary tends toward the accessible Anglo-Saxon, but includes Latinate sciencey words (dormancy, hibernation, etc.) as appropriate, doing the reader the compliment of not explaining them except in a glossary at the back. Despite the relative simplicity of the words, it's not an "Early Reader" in the strict sense, but it makes a great read aloud for younger kids. My 7 year old, 4 year old, their grandmother and I all loved this book.
The winner of the Toughest Creature on Earth competition, by the way, is the tardigrade. They've been heated to 300 F, frozen to -459, been put under pressure six times greater than that at the bottom of the sea, and into pressureless vacuums, they've been zapped with lethal doses of x-rays and poisoned with chemicals. And still they live...