Bioturbation is the reworking of soils and sediments by animals (including worms, snakes, trilobites, and crustaceans) or plant roots. The worms crawl in, the worms crawl out in these churned, turned over and under soils: check out this bioturbation video and watch the burrowing worms in action.
These ancient dirt churners were recently determined to have taken much longer to bioturbate than originally thought, by millions of years.
"For years, scientists thought bioturbation commenced in earnest with the Cambrian Explosion, 541 million years ago, when the complexity and diversity of animal species began to expand dramatically."
"But that wasn’t the case. In a new study published in the journal Nature Geoscience, researchers found that major bioturbation did not occur until at least 120 million years later, during the late Silurian Period."
Dr. Lidya Tarhan and researchers at Yale University propose that "Delayed bioturbation may have been responsible for regulating marine sulfate and atmospheric oxygen levels. A previously proposed drop in surface oxygen levels may be tied to the onset of extensive bioturbation, given that “oxygen is directly tied to the burial of organic carbon,” Tarhan said. “Less burial of organic carbon, due to bioturbation, means that more oxygen is used to respire or burn through that carbon, and thus oxygen decreases.”"
Thank heavens for worms and other bioturbators!
And of course, there's evidence of mass bioturbation (wait for it. . .):
As the Worm Turns,
I am not especially fond of the color pink, but I do like these kindergartners' style for our "NOVEMBER is CHEMISTRY MONTH" experiment with Chromatography and ROY G BIV.