|Gregarious cyanobacteria|In: Environmental Microbiology. Blackwell Scientific Publishers: Oxford. ISSN 1462-2912, meer
Huber and collaborators reported in this issue ofEnvironmental Microbiology about freshwaterpicocyanobacteria that showed phenotypic plasticityin the sense that they appeared as single cells as wellas in aggregates. The authors suggested thataggregation might be an inducible defense as aresponse to the presence of grazers. This has beendescribed for eukaryotic phytoplankton and for thecyanobacterium Microcystis but thus far not forpicocyanobacteria. Although inducible defense as anexplanation is an attractive possibility, it is alsoproblematic. Aggregation is common amongcyanobacteria and it offers many advantages ascompared with a free-living lifestyle. Here theseadvantages are highlighted and the possibility ofinducible defense is critically assessed.