Pleurosigma (a marine diatom). Credit: Michael
Stringer, Westcliff-on-Sea, Essex, UK. Source.
For some time, I've had the urge to learn something about diatoms. They are dazzlingly beautiful, relatively easy to manipulate, and have left a fossil record immense in quantity. I never had followed up on this yen, so here’s my chance. A recent paper shed light on the way they make their hard shells.
Diatoms are busy creatures, accounting by their photosynthesis for about 20% of the global primary production of organic material, an amount comparable to that produced by the tropical rain forests. They are single cells contained within a shell made up of glass (silica), which is what gives many of them often stunning shapes. Silica does not readily decompose and fossil diatom shells accumulate in prodigious quantities. Such deposits can be hundreds of meters deep in some places (fossils by the truckload!). Diatomaceous earth, as the rock consisting of fossil diatoms is called, has a large number of industrial uses, such as filtering pool water, absorbing oil spills, as a mechanical insecticide, as a mild abrasive (it may well be in your toothpaste!), and even as a component of dynamite! And, as we will see below, diatoms also have novel and unexpected uses.