Full text loading...
Chapter 36 : The Ship That Led to Shape
Bacteria, like all creatures, use every available tool to increase their odds of surviving, including adopting specific shapes. Long or very tiny bacteria resist being eaten by protozoa, very long ones are not easily washed from the soil, thin cells accumulate nutrients more readily from watery environments, rod-shaped bacteria move more certainly towards food sources, spherical ones may produce more progeny per gram of resource, spiral ones race more quickly through viscous fluids, flat ones expose more surface area to light, cells just the right size float at just the right depth in lakes and oceans, and triangular cells fit together like so many slices of pie. In fact, spherical cells appear to be dead ends, because once a family line becomes coccoid, no later generation returns to being a rod. So it looks like spherical cells are degenerate forms, not primordial ones. Instead, individual cells are gloriously weird and highly aberrant, so that a single culture represents almost every known bacterial shape. So far the morphologies are random, and a mutant that has not been isolated grows with just one particular new shape. But the fact that mutants explore the “shape universe” implies that a bacterium can adopt any shape. All that is needed is a mechanism to capture a specific shape and fix it in place. As the community of researchers identifies and investigates these mechanisms, we will, once again, be following in Charles Darwin’s footsteps as we complete our understanding of how and why these came to exist.