Lessons from the Past: Sponges and the Geological Record

Abstract

Sponges have been a major part of marine ecosystems, in both shallow and deep water, from the time of the earliest animal communities. The great shifts in climate that have occurred over the past 541 million years have affected all organisms, including sponges. Although patchy knowledge of the sponge fossil record hinders recognition of trends, some general patterns are apparent. Shallow-water siliceous sponges were severely affected by glacial intervals, whereas deeper-water siliceous sponges appear to have flourished during these times. Some groups of hypercalcified sponges (such as stromatoporoids) were abundant during times of global warming and high sea level, but other groups (archaeocyathans and sphinctozoans) had their acme during times of low sea level and relatively cool climate. Overall, sponge diversity appears to have been controlled more by sea level than by climate: large-scale sponge biotas occurred at times of high sea level, when there were large areas of shallow sea.