For the kinds of animals that are most familiar to us -- ones that are big enough to see -- it's a no-brainer: Is it better to sit around and wait for food to come to you, or to move around and find it? Larger animals that opt to sit around aren't likely to last long.
But for bacteria out in the ocean, the question is a far more complicated one.
Oceanographers have long assumed that because turbulence distributes nutrients uniformly through the water, and because the ability of tiny organisms to move around is insignificant compared to this turbulence, there was no reason for such creatures to move at all. Sea-dwelling bacterial life, they believed, should consist just of static feeders.
That view has now been upended by research conducted by Roman Stocker, an associate professor in MIT's Department of Civil and Environmental Engineering, and John R. Taylor, a former MIT postdoc who is now a lecturer in applied mathematics and theoretical physics at Cambridge University. It turns out that swimmers and passive feeders each have some advantages -- but also pay some costs -- in food gathering, depending on how fast the swimmers swim and how strong the turbulence is.