The freshwater mussels that inhabit the streams of Illinois spend most of their lives buried in the substrate, exposing only the parts they use to take in and expel a steady flow of water, from which they filter their food. This mode of living poses certain challenges for the scientists whose work it is to monitor mussel populations. As Illinois Natural History Survey (INHS) field biologist Alison Price explained to me, it is sometimes possible to sample for mussels visually, but only in waters that are shallow and clear enough to afford a good view of the streambed—a rare case in the Prairie State. More often, she and her colleagues sample for mussels by “grubbing.” “It is what it sounds like,” she quipped. “You reach down and rake your fingers through the sand and gravel until you feel a shell.” … Read the full story here.