Symbiosis between methane-oxidizing bacteria and a deep-sea carnivorous cladorhizid sponge

Dense bush-l~ke clumps of several hundred ~n d ~v l d u a l s of a new specles of Cladorhiza (Demosponglae, Poeciloscler~da) were observed near methane sources in mud volcanoes 4718 to 4943 m dcep In the Barbddos Trench The sponge tissue contalns 2 maln m o ~p h o l o g ~c a l types of extracellular symbiotic bacteria small rod-shaped cells and larger cocco~d cells with stacked membranes Stdble carbon ~s o t o p e values, the presence of methanol dehydrogenase and ultrastructural observatlons all lndlcate that at least some of the syrnblonts are methdnotrophic Ultrastructural e v ~d e n c e of ~n l r a c e l l ~~l a r d ~g e s t ~o n of thp s y n ~b ~o n t s and the stable C and X values suggest that thc sponge obtalns a slgnlflcdnt portion of its nutr~tlon from the symbionts Ultrdstructure of the sponqe embryo suggests d ~r e c t transmission throuqh qc.neratlons In brooded embryos The sponge also ma~ntrilns a carnivorous f e e d ~n g hdblt on tin\ swlmmlng prey, as do other cladorhlzlds K E Y L\/ORDS. Methanotrophy POI-~fera . Deep-sea .