Walden Pond Is Now Teeming With Jellyfish—but Don’t Panic

One 2020 sighting at the pond made it onto the United States Geological Survey’s Nonindigenous Aquatic Species database. Someone apparently spotted the jellies near a sandbar, between 50 and 150 feet offshore, suspended between three and 15 feet below the water’s surface. That report classified the population as “established,” and it will probably remain that […]