Diopatra cuprea , a predaceous, tube-building polychaete, has been cited as a possible modern analog of the Skolithos organism. In this investigation we examine the spatial distribution of Diopatra across tidal flats, study their dispersion within a population and compare the results to Cambrian Skolithos ichnofossils. The number and position of worm tubes within a 1 x 1 meter grid were recorded for each station. Over all stations, the number of worms per grid varied from 0 to 83, the average being 9 worms.
Densities are at a maximum near the mean low-water line, and decrease into the subtidal zone.
Results of the application of the Clark and Evans nearest neighbor technique to the worm distribution within each grid indicate that at high densities Diopatra are significantly clustered whereas at low densities their distribution is highly variable. An R value of less than 1 indicates clustering. Both Skolithos and Diopatra show significantly aggregated populations concentrated near the low-water line.