The unique intertidal subterranean habitat and filtering system of a limpet-like brachiopod, Discinisca sparselineata

Abstract

Living limpet-like brachiopods, Discinisca sparselineata (Inarticulate), were found in a unique intertidal subterranean habitat in the Seto Inland Sea, Japan. They were attached beneath boulders that were deeply buried in coarse sand in the middle intertidal zone, and were accompanied by a characteristic sessile epifauna. The habitat was protected from ultraviolet light, desiccation, turbidity, physical turbulence by harsh waves, disturbance by rock-scraping epiphyte-grazers, and from predation by carnivorous snails, seastars, and fishes. The filter-feeding mechanism is unusual in that water enters the mantle cavity frontally and exits laterally through lateral filaments and dorsally through ventrally directed spires as in D. strigata, which is distributed on the Pacific coast of Central America. However, D. sparselineata inhabits more protected habitats and has less capacity for spatial competition than D. strigata.