Abstract

Observations from compound, confocal, and scanning electron microscopy reveal that the buccal organ in Capitella teleta Blake, Grassle & Eckelbarger, 2009 should be classified as a dorsal pharynx. This buccal organ is an eversible proboscis that has the following characters: (1) dorsal ciliated pad, (2) well-developed pharyngeal retractor muscles, (3) pharyngeal gland-like structures, (4) cuticular fold surrounding the dorsal ciliated pad, and (5) unciliated buccal cavity and anterior ventral epithelium. All of these features are characteristic of dorsal pharyngeal organs present in oligochaetes and one terrestrial polychaete. Our observations in C. teleta confirm the presence of a dorsal pharynx in larvae, juveniles, and adults. C. teleta is a subsurface deposit feeder and a dorsal pharynx may have evolved independently in Capitellidae through selection of feeding mode in benthic marine habitats. Our results represent the first detailed description of a dorsal pharynx in a marine polychaete.