Functional Morphology of Animals

As a field, functional morphology aims to understand how morphological form is related to function in the broadest sense. The goals of functional morphology are twofold. The first goal is to understand whether different body forms and physical structures (e.g., bone dimensions) match in a logical way with the functions that they appear well suited for (e.g., locomotion, feeding), and whether such matching makes sense in an evolutionary and ecological context. A second goal is mechanistic; namely, to understand how basic functions, such as locomotion, occur by examining lower-level components, such as muscles, bones, and heart tissue. However, the field of functional morphology is heterogeneous and has several subfields, each of which has its own history and traditions, and each of which adds generally to the broad goal of relating form to function. These subfields include functional anatomy, biomechanics, ecomorphology, and evolutionary functional morphology. Functional anatomy predominated for many centuries, and it aimed to infer function from structure. While it remains today as a conceptual tool, it has largely been supplanted by direct measurements of animal function. Biomechanics unites the science of material properties and physics to understand animal movement. Ecomorphology represents an infusion of functional morphological techniques into the field of ecology, and it is useful for understanding specializations to different habitats. Finally, evolutionary functional morphology integrates principles of evolutionary theory with functional morphology. Evolutionary functional morphology has blossomed in particular over the last several decades. The field of functional morphology in its present form came fully into existence in the 1950s and 1960s, but underlying ideas about how form relates to function have been in existence at least since the time of Aristotle. An exact timeline is challenging, but the field was dominated for many years by anatomists, who inferred how form related to function. The advent of technological innovations in the 1950s and 1960s that allowed the visualization of movement and the monitoring of internal structures such as muscles allowed the field to mature such that both form and function could be empirically studied. Whereas research in the 1960s and 1970s was limited to a few model species that could be examined using only a few techniques, the modern field employs a wide array of techniques, both in the field and in the laboratory, and examines many kinds of animal species. The field has evolved from simple descriptions of external form, anatomy, or movement to highly detailed empirical analyses of body movements using high-speed video (kinematics), and force plates (kinetics). Functional morphology is inherently comparative, and it examines many kinds of species (e.g., birds, lizards, mammals) that occur in different environments (e.g., aquatic, terrestrial).