A book about how animals use their bodies and how they behave and why. Each chapter looks at a separate stage in the life of animals and how they all have to solve a particular set of problems if they are to survive and eventually pass on their genes to the next generation. The crab with stinging boxing gloves, the mother bat finding her baby among 10 million others, the cleaner-fish whose customers queue up in the sea, the lion who kills the cubs of a rival, the navigating ant and the viper that is a caterpillar - all behave as they do for the same ultimate reason.