A scanning electron microscopic investigation of the outer surfaces of Gorgoderina attenuata

The external surface of Gorgoderina attenuata is characterized by ridges that encircle the worm at regular intervals. On the ridges are protuberances that give a beaded appearance to the tegumental surface. Ridges running perpendicular to the encircling bands are apparent close to both suckers. The raised protuberances of the tegumental areas may serve to increase the absorptive surface. A pit-like cavity was observed on the dorsal surface of the oral sucker. In addition numerous raised structures which appear to be of two types were present on the surface of the oral sucker. One type resembles a depression with a small knob barely visible in the center and the second type consists of button-like patches of tissue. From their structure and location these are tentatively identified as sensory organs.