10 things you didn’t know about jellyfish


A box jellyfish sting can kill a person in under 5 minutes

The largest species of box jellyfish, Chironex fleckeri, has one of the deadliest venoms known to man. It disrupts electrical signals within the body, and can rapidly cause the heart to fail.


Jellyfish have been around for 500 million years

Jellyfish are one of the oldest complex life forms on the planet. They were also some of the first to evolve muscle-like structures, and to use them as a means of propulsion through the water.


Jellyfish are 95% water

Between the outer skin and the lining of the digestive cavity, jellyfish are composed of a gelatinous substance known as mesoglea. It contains elastic proteins that give the jelly its flexibility, but it is mostly water, and often completely transparent.


Jellyfish have been sent to space

Despite their simplicity, jellyfish can be used as animal models to investigate the effects of space travel on the human body. In 2001, NASA fired jellyfish polyps into space in order to investigate the effect of zero gravity on their ability to tell up from down.


One jellyfish is immortal

This small jellyfish is the only known life form to be able to revert back from its adult form into a juvenile. When stressed, the medusa transforms back into a polyp, forming a new colony that goes on to produce young jellyfish. In theory, this process could go on indefinitely, but whether it does or not is unknown.


Jellyfish proteins were used to make fluorescent kittens

Crystal jellyfish are bioluminescent, and produce green fluorescent protein. In 2011, a laboratory in the USA inserted the gene for this protein in to the eggs of female cats, producing kittens that glowed green.


A single jellyfish stung 100 people in one day

In 2010, over 100 people were stung by a jellyfish during a single day on Wallis Sands State Beach, New Hampshire. The culprit is thought to have been an 18kg (40 lb) lion’s mane jellyfish that rode in to the coast on a tidal wave, and subsequently washed up on the shore.


Jellyfish can break a nuclear power plant

Nuclear power plants draw water from seas and oceans in order to cool their reactors and turbines. In recent years, several nuclear reactors across the globe have had to close their reactors after jellyfish blooms clogged the intake pipes.


Jellyfish inspired a robot flying machine

Scientists striving to make the simplest flying machine looked to the shape of jellyfish. The frame of the robot is based on a similar principle and is domed in shape, with four wings that open and close.


Peeing on a jellyfish sting does not work

The poplar US sitcom Friends, perpetuated the myth that urinating on a jellyfish sting eases the pain. In fact, most home remedies, including ammonia, bicarbonate of soda, lemon juice, fresh water, alcohol and ice are ineffective. Some methods, like flushing a box jellyfish sting with vinegar, can actually make the situation worse.