Figure 4.

Attached sulfur bacteria. (a, b) Densely packed Thiomargarita-like cells on gastropod shell co-occur with attached filamentous bacteria. Scale bar in a=30 μm; b=20 μm. (c) Particularly during early stages of attachment and elongation they have rounded bases where they are attached to benthic substrates. As the cell elongates, the base of the cells becomes tapered. In some specimens, a small appendage formed by extrusion of the cell ultrastructure is present. (d) Transmission electron micrograph of vacuolated Thiomargarita-like cells (t) attached to plaque (p) and mucous occupied by smaller filamentous bacteria. This material surrounds the Bathymodiolus mussel byssus. Scale bar=2 μm.