Spiny waterflea (Bythotrephes longimanus)
https://www.dnr.state.mn.us/invasives/aquaticanimals/spinywaterflea/index.html
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A microscopic adult spiny waterflea. Photo: University of Minnesota Aquatic Invasive Species Research Center (MAISRC)
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Fishing line tangled with spiny water fleas. Photo: University of Minnesota Aquatic Invasive Species Research Center (MAISRC)