However, their fishing success is one thing. Their survival is quite another. To dive into water from 100 feet may not be lethal for a gannet, but it would, or should, get a fearful migraine. Yet that doesn’t seem to happen. Gannets manage to bob to the surface with all their mental faculties intact, their brains entirely unhurt.

And how? Skull modifications, just as with the ram and the woodpecker. In this case, to mitigate the brain-shattering trauma of a 60-mile-an-hour collision with a wall of water, air sacs built into the gannet’s face act as cushion; its extremely long and narrow beak helps the bird enter the water with only a very stealthy kind of impact; and it has no nostrils that would allow water to gush inward and do serious damage to the delicate tissues inside. A gannet’s skull is built like the nose of a Concorde: strong, delicate, unpierced, and able to tilt downward on landing but hold straight ahead when passing at great speed through the water.

Modifications of the skull are many, all produced by evolution to give each animal maximum advantage in adapting to its environment and its lifestyle niche. Some skulls are narrow and delicate — the gazelle’s, say — while others, like that of the lion, are squat and fat and powerful: the owner of one grazes and has the grace to prance away; the owner of the other stays put and waits for chance to bring him the opportunity to crush and to kill.

Invariably the melding of form and function is displayed perfectly in an animal’s skull — so that one can quite easily deduce the manner in which the animal behaves, or the environment in which it lives, by examining, or even by casually glancing at, the skull it leaves behind.

Compare the massive jaws of a wolf, for instance, with the more modest arrangements of the mouth of a hare; or look at the great ridges along the uppermost part of the skulls of some species — a mountain lion, for example, which has a sail-like arrangement known as a sagittal crest, to which the jaw muscles are anchored to give it even greater crushing power. If you come across an otherwise modest animal with a large sagittal crest — a coati-mundi, for instance — you’d do well to avoid it, or at least to keep it happy: When a coati fights, it bites, and when it bites, the muscles attached to its sagittal crest allow it to come down hard with its canine teeth, the ones that really hurt and do damage. In less threatening territory, the eye orbits on certain skulls can be spectacular — the immense orbits of a tarsier, for example, are often as large as the entire rest of the skull; they provide a classic example of a skull detail that suggests how well or ill an animal can use a certain sense, in this case, its vision.

Similarly, structures called the auditory bullae can show, in bony form, just how well an animal can hear. Springhares and rabbits have very large auditory bullae: it’s said that the chamber enclosed by the bullae resonates perfectly to the whooshing sound of a downward-swooping owl, alerting the rabbit to dive for its burrow and live to enjoy another day.