Surface movement rates of the New Zealand flatworm Artioposthia triangulata: potential for spread by active migration

Movement rates for the surface activity of the New Zealand flatworm Artioposthia triangulata (Dendy) (Tricladida: Terricola) were estimated under semi-field conditions in the Faroe Islands. The distance travelled during 10 consecutive 1-minute periods per individual was measured from mucus trails left behind as the flatworms moved over black plastic sheeting sprayed with fine droplets of water. Adult specimens were found to crawl at rates of up to 28 cm min^-1 (almost 17m h^-1), whereas juveniles crawled at rates of between 3 and 4cm min^-1 (approximately 2m h^-1). This study provides the first data concerning the potential for species spread by active migration.