Photo by Gary Montz (https://www.invasivespeciesinfo.gov/profile/spiny-water-flea)
Spiny waterflea is a planktonic crustacean less than 15 mm (0.6 in) long. It typified by a long abdominal spine with several barbs which protect it from predators. When they are grouped together, as ensnared on fishing lines and cables, they collect and form gelatinous globs (see photo to right and below). They prey on smaller planktonic organisms and can decimate populations of native zooplankton resulting in a decreased food source for native fish and an increase in algal blooms. At their peak, their populations reproduce rapidly and can be as high as 100 individuals per cubic meter, sometimes taking over the biomass of the lake.
Spiny waterfleas were first introduced to the Great Lakes through ballast water. Today, recreational boaters and anglers can inadvertently move them or their eggs on fishing line, bait buckets, live wells, fishing nets, or shoes/sandals.
Spiny waterfles coating a fishing line.