Vinegar eels forming a torus

 I ran across an article in Science News this week about the curious discovery that a tiny nematode called vinegar eels (because they swim around in raw vinegar) are able to engage in synchronized swimming when confined to a single water droplet. This synchronization of movement is quite unusual and unexpected. Here's what they look like when this happens:

 Turbatrix aceti, a species of nematode commonly known as vinegar eels, engage in synchronized swimming when confined to a water droplet. photo: ANTON PESHKOV

These vinegar eels coordinate two types of movement, directional motion plus oscillation, to create the torus shape pictured above. Confinement to a globular water droplet is required in order to coordinate these movements, otherwise the tiny nematodes swim by themselves through their liquid mediums.

The toroidal distribution exerts a measurable outward pressure toward the outside of the droplet to keep it from collapsing inward. 

Scientists are puzzled as to how these mindless, primitive organisms can coordinate this complex behavior. Such behavior has been predicted by computer modeling of fluid dynamics, but this is the first example discovered in living organisms.

The original report appears in the journal Soft Matter.

Synchronized oscillations in swarms of nematode Turbatrix aceti

Anton Peshkov,    Sonia McGaffigan and  Alice C. Quillen   

Here is another look at the nematodes in the process of organizing themselves into the torus.