The geomorphic effects of invertebrates are apparent to even the most casual observer who has seen an ant mound or earthworm castings. Invertebrates as geomorphic agents have been examined in a number of recent studies, but far fewer than those that examine their pedoturbational role. The papers by Goudie (1988) and Mitchell (1988) provide comprehensive review of the geomorphic role of select invertebrates, especially earthworms and termites. I do not attempt to duplicate the success of those papers here, as the emphasis of this book is on the geomorphic influences of vertebrates; rather, it is my intent in this chapter to summarize the geomorphic processes associated with invertebrates, and to present select examples of the geomorphic features they produce. In keeping with the emphasis outlined in Chapter 1, I concentrate on terrestrial invertebrates and offer only a brief survey of coastal and marine invertebrates.

Geomorphic effects of terrestrial invertebrates

Many insects, arachnids, and worms, as well as some crustaceans, are burrowing animals. Because burrows are underground phenomena, it is easy to believe that invertebrate burrows and the quantity of sediment they displace comprise small numbers, except in cases where material from underground has been deposited on the surface, as in the case of ant mounds (Fig. 2.1). The following sections illustrate the impressive nature of geomorphic work that a variety of invertebrates are capable of accomplishing.