The circumstances highlight a greater issue. Swarm of jellyfish overwhelms nuclear power plant, causes several reactors to shut down — here's what happened first appeared on The Cool Down.

Since its inception, nuclear energy has faced a host of opposition, from oil conglomerates to well-intentioned anti-nuclear-weapons activists to environmental groups. As it turns out, even ocean critters are getting in on the movement.

Four reactors at France's Gravelines nuclear plant will return to operation throughout the week, slightly later than initially planned, EDF data showed on Tuesday, after they were forced offline by a swarm of jellyfish in the cooling systems.