Zoology: Inside the Secret World of Animals

Book Preface

Beauty is alluring, truth is essential, and art is surely humanity’s purest reaction  to these ideals. But what of that other irrepressible human trait—curiosity?  Well, for me curiosity is the fuel for science, which in turn is the art of  understanding truth and beauty. And this beautiful book presents a perfect  fusion of these paragons, celebrating art, revealing remarkable truths, and  igniting a curiosity for natural science.

In life all form must have a function, it can be in transition, but it’s never  redundant. This means that from childhood onward, we can study and  question the shapes and structures of natural forms and try to determine  what they are for and how they work. I remember examining a feather,  weighing it, preening it, bending it, twisting it to watch its iridescence flash  from green to purple, all the while working through a process of understanding  why it was an asset to bird flight and behavior. Such investigation is perhaps  the most fundamental skill of a naturalist and the essential technique of a  scientist. And then I tried to paint it, its simple beauty the inspiration for art.
Natural forms also allow us to identify relatedness between species,  throwing light on their evolution, which in turn opens our eyes to how we  group them together. Of course there are tricksters—mammals with beaks  that lay eggs! It’s certainly fun to discover how our predecessors were fooled  by these strange anomalies, but it’s even more satisfying to uncover the truth  as to why animals evolved such apparently bizarre forms.

This book reveals that nature is not short of such fascinations and revels in  the joy that we can never completely satisfy our curiosities because there is  always more to learn and know about life

what is an animal?
Animals differ from the two other major kingdoms of multicellular organisms—fungi  and plants—in the fabric of their bodies. Animals have collagen protein holding their  cells together into tissues, and and all but the simplest use nerves and muscles to  move. Whether rooted to one spot like sponges, or as active as ants, animals  gather food. Unlike fungi that absorb dead matter, or photosynthesizing  plants, animals feed on other organisms.

evolution
All animals alive today have descended from different animals in the past by a process of  evolution. No single individual evolves, rather entire populations accumulate differences over  many generations. Mutation—random replication errors in the genetic material—is the source  of inherited variation, while other evolutionary processes, notably natural selection the driving  source of adaptation—determine which variants survive and reproduce. Over millions of years  small changes add up to bigger ones, helping explain the appearance of new species

types of animal
Scientists have described some 1.5 million species of animals. They organize this  diversity into groups of animals whose shared characteristics suggest common  ancestry. Some, such as echinoderms, have a starlike radial symmetry; others have bodies arranged like our own—with head and tail ends. Most are popularly called  invertebrates, because they lack a backbone. But invertebrates as different as a  sponge and an insect otherwise have nothing uniquely in common and no direct evolutionary relationship, so scientists do not recognize them as a natural group