ABOVE: The ciliate Pseudoblepharisma tenue harbors both green algae and purple bacteria as symbionts. SEBASTIAN HESS M ore than a century ago, a German schoolteacher named Alfred Kahl made a career ...

Related: Pond Maintenance Tips for a Stunning Landscape in Every Season Algae can encompass many types of protists. "'Algae' is a broad term that can apply to diverse photosynthesizers that lack ...