Energy is a familiar concept in the everyday lives of most people, even if they are unable, when asked, to conjure up the physicists’ precise definition. We tire during exercise and feel refreshed after an “energy drink.” Our dog runs along the beach for no reason, so it seems, other than the joy of life—he is “full of energy.” Physicists tell us that energy is a real thing, like matter, but outside the realm of Einstein’s relativity, it is not a material. Instead, it is a property of a material and can take many forms: heat energy, chemical energy,...

An animal’s structure is based on its skeleton, just as a building’s is based on its frame. Frames vary enormously and so do skeletons. Many skyscrapers have a central core that supports the weight of the building—a backbone. Other buildings are designed to be supported by the external walls—a carapace, or exoskeleton. Different designs suit different purposes; one of the main impressions that emerge from even a cursory survey of animal anatomy is the structural diversity that exists. A good idea (say, the development of keratin, a tough, fibrous protein) blossoms over eons into a hundred variants (including...

“Cheetahs and beetles run, dolphins and salmon swim, and bees and birds fly with grace and economy surpassing our technology.” So wrote the authors of a long (nearly 100 pages) and highly mathematical paper on legged locomotion.¹

These first two sentences encapsulate the challenges of this chapter. There are many ways that animals, of very different biological architectures, can move around. They may walk, trot, pace, canter, bound, pronk, or gallop away from predators; they may slither, slide, or crawl into burrows; they may flap, soar, or glide in search of a mate; they may swim or jet-propel their way...

Animal computing crops up in several chapters. It is intimately bound up with engineering functionality—for example, vision and signal processing, or locomotion and feedback control, as we have seen. Computing merits its own chapter not just because it is important, but also because it exhibits a number of features that may not come up in a discussion of vision processing or feedback control.

Let’s begin with a simple experiment. Read the following instructions. Then, without any further thought or inner debate, carry them out:

Put this book down on a flat surface within easy reach. Turn your head away,...

This chapter is about the structures that animals build. Th at covers beehives and termite mounds, ant nests and bird nests, beaver dams and gopher tunnels, and even spiderwebs, but there is much more to the story of animal construction engineering than the things they construct.

We all know that nests, dams, and tunnels are built by animals but are not part of the animals. In many cases, such as spiderwebs, the structures are even built from the animals: the building materials are made in their bodies. But we still think of the web as an external item, built by,...

Most of this chapter will be concerned with animal behavior. You will not learn how to tell if a ferret is friendly or an iguana irritated. Instead we take a look at some of the control algorithms that make animals behave the way they do. In particular, we ask the question: how simple can they be?

We’ve already looked at animal brains and the mechanisms they use to control the body. From an engineering viewpoint we’ve seen that, like any machine, an animal has an information processor for making decisions and a control system to implement those decisions. However, a...

Human beings are highly visual animals. We experience the world through our eyes. Sight so dominates our lives that visual metaphors dominate our language—if you see what we mean. If not, we’ll cast more light by stating it bluntly: humans see the world around us.

Other animals are different; they rely primarily on a chemical sense that we call smell. They need to find the food chemicals that provide the energy and raw materials required for survival and growth; they need to identify and avoid those chemicals that represent threats to their survival, in the form of predators or...

Bioacoustic passive receivers (“ears”) have evolved many shapes and sizes in many groups of animals—an elegant expression of the usefulness of hearing. In this chapter we share some of the engineering ideas associated with passive acoustical sensing (listening to what is out there); in the next chapter we delve into the more intricate world of active acoustical sensing (echolocation).

Here we restrict ourselves to sound that travels through fluids—air or water—and so say little about vibrations traveling through solid matter. Such vibrations are indeed sound waves, but the receptors developed by animals for sensing them are different....

Most people know that sonar (sound navigation and ranging) is a technique warships use to sense the presence of enemy submarines amid the murky depths of the sea, where vision is impossible. They consider (rightly) that sonar is similar to radar, except instead of transmitting electromagnetic waves, sonar employs acoustic waves. In fact, sonar is in many ways exactly the same as radar; the differences between the two remote sensing techniques are almost entirely due to the different types of wave that are transmitted. Sound waves are quite different from electromagnetic waves, and these differences present different problems for the...

Physicists recognize four fundamental forces of nature. Two of these—gravity and the electromagnetic (EM) force—are important to biologists and engineers (the other two are locked up in atomic nuclei most of the time). The electromagnetic force manifests in three forms: as electric fields, as magnetic fields, or as a combination known as EM radiation. The animal kingdom includes members that can, among them, detect all these manifestations and use them to perceive the world around them. We concentrate here on passive EM sensors (“eyes”), because these are the most common manner in which animals utilize the Em force....

Animal navigation conjures images of the long-distance migrations of birds. It’s an easy association to make, because bird migration is an annual event that we tend to notice. Birds are, indeed, capable of prodigious feats of navigation and so will figure prominently in this chapter. But it would be a mistake to dismiss the rest of the animal world in this context; there are four-legged (and six-legged, and no-legged) animals who are experts in many aspects of navigation science. Best known, perhaps, are Monarch Butterflies and salmon. We examine the achievements of these and many other migrants, as well as...

In going about their daily business, all animals cannot help but emit signals of one sort or another—chemical, auditory, visual, or electrical. As we have seen, other animals have evolved senses to detect those signals. However, the emission of a signal detectable by another creature is not necessarily communication. Entire libraries have been filled with discussions of what is, or is not, communication, but we keep things simple.¹ For our purposes communication is about passing messages between animals. It requires two things—deliberate intent and encoded information. By this we mean both that the signal is emitted intentionally and...