Observations on tidal flats in North Inlet, SC suggested facultative suspension- and deposit-feeding in the chaetopterid polychaete, Mesochaetopterus taylori. Fecal coils consisted of two disparate sections, the first composed of small, brown fecal pellets wrapped together by mucus into long strands, which abruptly transitioned into a second gray, ropy section. We also made direct observations of exposed palps and probing of the sediment surface intermittently following tidal emersion. Granulometric analyses of gray and brown fecal material, surficial sediments, subsurface sediments, and materials in suspenson above the worm at high tide, corroborate our field observations that M. taylori is a facultative feeder, switching from suspension- to deposit-feeding with tidal emersion. Typically, this shift in feeding mode is not thought to effect a fundamental change in diet, i.e., the same materials are ingested, suspended or deposited depending on hydrodynamic regime. In contrast, M. taylori ingests finer particulates during tidal immersion, with concomitant differences in granulometric characteristics. The distinct provenance and composition of the dietary components of M. taylori likely supplies a relatively broad range of essential nutrients. The geophysical effects of M. taylori feeding are likely profound, in that it both translocates subsurface sediment to the surface during deposit feeding and deposits fine, suspended materials following filter-feeding.