Introduction

Abstract

Probably the best known animals with larvae are butterflies with caterpillar larvae. Butterflies and caterpillars are evolving together, but I question whether they have always done so. There were caterpillar-like animals before there were flying insects, and I hold that a cross between members of these two, distantly related groups produced the first insect with a caterpillar larva. Caterpillars are just one of dozens of examples discussed in this book, and they illustrate the principle that, I believe, applies to all larvae and all embryos. This states that the basic forms of larvae and embryos were transferred from other taxa and were later additions to the life-histories of existing adult animals. I call this process ‘larval transfer’. In the chapters that follow, I describe the ways in which animals develop (their ontogeny). I discuss links between their ontogeny and their phylogeny (evolutionary history), and I explain these links in terms of larval transfer.