Ecology and Palaeoecology

As major components of hard substrate communities since the Ordovician, bryozoans have ecological and palaeoecological importance. Some aspects of bryozoan ecology and palaeoecology, notably functional morphology and biotic interactions, have been covered already and this chapter concentrates on the habitats colonized by bryozoans as well as their broader facies associations. The ecology of living bryozoans must guide and inform our interpretations of the bryozoan palaeoecology and the nature of the ancient communities in which they lived. The limited value in stratigraphy of the typically long‐ranging and often patchily distributed bryozoans is widely acknowledged, notwithstanding a few regional applications (e.g. Mesentseva 2008). Therefore, the practical use of bryozoans in geology has focused on their value as ‘facies fossils’ to provide insights into palaeoenvironments. Colony‐form has been widely employed for this purpose, despite our imperfect knowledge of the distributions of different bryozoan colony‐forms across the spectrum of environments inhabited by these animals. More recently, zooid size variability has been used as a proxy for temperature seasonality (MART analysis). This, along with ecophenotypic variations in colony‐ form within species, may be more useful as palaeoenvironmental proxies.