At first glance, there is nothing special about the barrel jellyfish, also known by the rather undignified name of the dustbin-lid jellyfish. Sure, Rhizostoma pulmo is one of the larger jelly species—it can grow to about three feet across and weigh upwards of 70 pounds—but it’s not the biggest, or the most dazzling. (The lion’s mane jellyfish is a candidate for those titles, though a 2019 video of an exceptionally large barrel jellyfish swimming past divers made quite a splash.) Barrel jellyfish do sting, but they evolved to stun teensy…
