Scientists say jellyfish are taking over the seas, and it may be too late to stop them.
They have no brain and are made of 95 percent water. Jellyfish are mysterious creatures with a nasty sting, and some experts fear a jellyfish invasion could be on the way.
Just last week, a wave of jellyfish forced one of the world's largest nuclear reactors to shut down. Operators of the Oskarshamn nuclear plant in southeastern Sweden had to scramble a reactor at the nuclear plant after jellyfish clogged the pipes that bring in cool water to the plant's turbines.
It took three days to clean the pipes of the jellyfish.
A similar situation happened last year in California.
Some say this could become more common.
Experts claim the creatures could wreak havoc in our oceans, posing a threat to human life and blocking up large coastal structures.
The problem, claim experts, could be largely caused by human activity in the ocean.
Complex ecosystems used to keep the jellyfish at bay. But now due to human involvement and manipulation, jellyfish numbers have exploded.
For example, plastic bags and drift lines can destroy sea turtles… one of the few natural jellyfish predators. Also, jellyfish use litter, like industrial waste, to make large nurseries.
Over fishing is also considered an issue.
But even on the most basic level… jellyfish are hard to stop.
As one expert puts it, 'hermaphroditism, cloning, external fertilization, self-fertilization, courtship, copulation, fission, fusion, cannibalism… you name it, jellyfish are doing it.'
One type of jellyfish named the Mnemiopsis can lay eggs when it is just 13 days old without a mate. It can lay 10,000 eggs per day. It can eat more than ten times its own body weight in food, and it can double in size each day.
Then there is the zombie jelly. This one is seemingly immortal. When its particles disintegrate, cells escape and form an entirely new jelly. All is takes is five days.