Toward a New Zoology

Abstract

This book is about one aspect of animal development and evolution, but there are several other aspects of this broad theme that it either ignores or barely discusses. It seeks to explain a number of anomalies in larval form and methods of metamorphosis, but it adds nothing to existing theories on the origins of larvae. It emphasizes the evolutionary distinction between radial and bilateral symmetry but adds nothing to our knowledge of the origins of either. It opens up a new aspect of ontogeny and phylogeny that has very little to do with neoteny, paedomorphosis, and recapitulation. I have tried to show that there are a great many examples of larvae and a smaller number of examples of embryos that, in terms of neo-Darwinian evolutionary theory, seem out of place with respect to their corresponding adults.

Problems of classification if present theories accepted—New life-histories acquired by horizontal transfer may have led to accelerated evolution—Possibility of horizontal transfer affecting adults, leading to ‘hopeful monsters’—Urochordates present possibility of adult of one group having become larva of another after horizontal transfer—Suggested reclassifications of some animal groups—Need for broader debate on principles of phylogeny and taxonomy