Mycoplasma-like organisms: occurrence with the larvae and adults of a marine bryozoan.

Larvae and adults of the marine bryozoan Watersipora cucullata invariably possess numerous extracellular mycoplasma-like, organisms. Mesodermally encapsulated groups of these atypical bacteria occur in the visceral coeloms of all colony members. In contrast, thousands of the symbionts are externally attached to each larva along a unique superficial groove; the microorganisms are internalized during the complex metamorphosis, thus inoculating the incipient colony. The consequences to the bryozoan of this association are not known.