the-circles-of-life:Pterodrilus distichusCrayfish Worm ft. Bronwyn W. Williams Bronwyn enjoys show
the-circles-of-life: Pterodrilus distichusCrayfish Worm ft. Bronwyn W. Williams Bronwyn enjoys showing people creatures that they never knew existed, but live in or near their backyard. “I also enjoy doing so using a form of charades to explain what they look like and how they move, often like a drunk inchworm,” she starts. Pterodrilus distichus is a tiny worm that doesn’t grow larger than 1 mm in length. It has what Bronwyn affectionately calls devil horns along its back, and a tail fan. “We have no idea what the back appendages are for, but they do have a tendency to collect all sorts of gunk, making them look like living, mobile dust bunnies,” she adds. These peculiar worms need to be on a live crayfish to reproduce, depositing cocoons containing embryos on the crayfish’s shell. If the crayfish molts, the embryos left on that molt die. It’s a very specific life cycle that’s fine-tuned by millions of years of evolution. She first heard about these worms when she was looking into a crayfish invasion in the Prairie Provinces of Canada. But the story has a twist: the crayfish had tiny worm companions. Back then, she was interested in invasion biology and genetics. She wanted to use genetics to figure out how crayfish from different habitats are related to each other, to understand how they spread. But instead of using the crayfish’s DNA, she used the worms’ instead, since their shorter lifespan means they breed faster and their genes change more quickly. Unfortunately, her crayfish research failed. But this led her to investigate the worms’ diversity instead. Today, she gathers crayfish in the field and looks for the worms clinging to their shells. Sometimes, the worms can also be found at the bottom of the jar in museum collections. Her aim is to determine how these worms vary spatially—across individual crayfish, crayfish species, habitats; and temporally—over evolutionary time particularly relative to their crayfish hosts. Even now, she’s wrapping up a scientific paper describing a new species that quickly becomes her favorite species. When the paper comes out in a few months, she’ll happily introduce the world to a new chubby little worm, one that Bronwyn affectionately calls The Michelin Man. — Bronwyn W. Williams, Ph.D. is the Research Curator of Non-Molluscan Invertebrates at the North Carolina Museum of Natural Sciences. Twitter · Lab — My main blog · Ko-fi · Patreon -- source link