A commensal relationship between a small filter feeding organism and Australian Devonian spiriferid brachiopods

Abstract

Open-ended tubes were found extending inward from the inner surfaces of brachial valves of three different species of Emsian spiriferid brachiopods. It is believed that these tubes were formed by the outer epithelium of the brachiopods, precipitating shell material around a small commensal filter feeding organism living in the outer mantle cavity. The position of the open ends of these tubes, the business end of the filter feeding organism, in every case discovered is between the bases of the two spiralia. This lends support to the suggestion of Ager (1961) and Wallace and Ager (1966) that spiriferid brachiopods had median inhalant and lateral exhalant feeding currents. These structures are named Burrinjuckia spiriferidophilia n.gen. n.sp. They are trace fossils of indeterminate taxonomic position.