Microflora associated with the digestive tract of the fairy shrimp Branchinella spinosa (H. Milne Edwards, 1840) (Crustacea, Branchiopoda)

An ectoperitrophic association of microorganisms with the fairy shrimp Branchinella spinosa was investigated by standard plate counts and scanning electron microscopy. Yeasts were found to form a monolayer structure attached to the inner surface of the peritrophic matrix suggesting a strong symbiotic association. The bacterial population consisted mostly of members of the genus Serratia, concentrated in the hindgut, and exhibiting chitinolytic activity.