Gill structure, anatomy and habitat of Anodontia edentula: Evidence of endosymbiosis

Abstract

Surveys and interviews were conducted to determine sources and habitat of Anodontia edentula. Results showed that they inhabit muddy substrate of mangrove areas or the adjacent mudflats, burying at 20-60 cm deep in the mud. They are strategically situated in the sulfide-rich, low-oxygen layer of the substrate but have access to oxygen through their inhalant tube; both sulfide and oxygen are essential for their survival. Study of the clam s gross anatomy revealed thick, fleshy, deep purple to blackish brown gills; reduced digestive structure; and a highly elastic foot capable of extending several times longer than its body length. These observations conform with the anatomy of fellow lucinid clams. Furthermore, scanning electron micrographs showed coccoid or spherical bacteria occupying bacteriocytes in the clam s gills. Intermediate cells separating bacteriocytes observed in other lucinids were also noted in the SEM.