Populations of plants and animals affect sediment transport and morphological evolution in many environments. The term 'ecogeomorphology' (or 'biogeomorphology') describes studies that address such effects. In this selective review we use the term 'biomorphodynamics' to characterize a subset of ecogeomorphologic studies - those that investigate not only the effects of organisms on physical processes and morphology, but also how the biological processes depend on morphology and physical forcing. The two-way coupling precipitates feedbacks, leading to interesting modes of behavior in some systems, much like the coupling between flow/sediment transport and morphology leads to rich morphodynamic behaviors. Select examples from river, coastal, and estuarine settings illustrate how even the basic aspects of some systems cannot be understood without considering biomorphodynamic coupling. Prominent examples include the dynamic interactions between vegetation and flow/sediment transport that can determine river-channel patterns, and the multi-faceted biomorphodynamic feedbacks shaping tidal marshes and associated channel networks.The prevalence of biomorphodynamic research is burgeoning in recent years, driven by a combination of scientific fashion, societal need, and a confluence of complex-systems inspired modeling approaches in ecology and geomorphology. © 2008 Taylor & Francis Group, London.