Characterizing the Morphological Ultrastructure of the Alimentary Canal of Megathura Crenulata (the Giant Keyhole Limpet)

Abstract

The Giant Keyhole Limpet (Megathura crenulata) is an intertidal archeogastropod whose range extends from Monterrey, California to Baja, California. Within the last decade, M. crenulata has become an animal of interest when it was found that its blood hemocyanin (KLH) is an extremely potent antigen. KLH is also currently in end stage trails for its possible use for cancer therapy, specifically for bladder carcinomas. Since it is believed that this protein will also be useful in the treatment of other cancers, the production of sterile KLH has become a multimillion-dollar industry. Although this is not an especially abundant animal, at this time profit-oriented people are simply bleeding animals and tossing them back into the ocean to die, while only a few groups are trying to culture M. crenulata and develop ways to bleed them without damage. This has led to some complications in keeping the animals alive and healthy, especially in view of the fact that only its hemocyanin has been studied extensively and the animal itself has been largely ignored. Studying the digestive tract will not only help us understand the nutrition of M. crenulata, but it will also help us in understanding how the animal protects itself from infection by pathogens. In this study, a variety of methods including light and electron microscopy (both TEM and SEM) as well as several histochemical and cytochemical studies will be used to characterize the different regions of its alimentary canal, and determine what enzymes are being secreted.