The independent microorganisms of our planet earth Part two Protozoa

Protozoa devour not only bacteria but also other protozoa. One of these, the didinium, is a voracious paramecium predator, and has an amazing resource to catch its prey. Biologists have carried out a thorough study of the method he uses to capture and kill them: the hungry didinium swims through the water more or less in a straight line, using its cilia fringe, until it stumbles (coincidentally, it seems) with a paramecium. Although the prey is almost as large as its prey, this sting stings its victim.  

 These harpoons seem to contain a poison that first paralyzes the paramecium, causing it to die immediately afterwards, then the didinium picks up its harpoons, dragging its victim with them to the inside of its mouth; once it has swallowed it, the predator with its considerably dilated body continues to swim to digest the food. It is incredible that all this complicated mechanism and weaponry is contained in a single cell.