What you need to know about this summer’s arch nemesis


Jellyfish are strange, don’t you think? After all, who thought that a creature made of jelly floating through the sea while being able to produce a hefty sting was a good idea? We’re not sure, but there is a lot more to these creatures than meets the eye. In fact, the science behind jellyfish might have you looking at them in a different way than ever before.

They’re not fish

Several creatures in this world have lied to us over the years. Just take koala bears – not really bears. What about guinea pigs? They aren’t pigs either. Jellyfish are no exception. They aren’t jelly or fish, but are actually a form of plankton! Although they might not run The Chum Bucket, they rule the sea thanks to their incredible power and numbers.

Jellyfish can’t swim

As well as not even being fish, jellyfish can’t swim. Instead, these creatures rely on the current to change direction. However, jellyfish do have some say in where they’re going. Perhaps you have seen one in the ocean as they pulse their tentacles? This is a jellyfish’s graceful way of moving up or down in the water.

That powerful sting

Talking of tentacles, how come a jellyfish can cause so much damage? No, they aren’t secretly electric. In fact, jellyfish are venomous. Their arms are covered in cells known as cnidocytes. These are filled with tiny harpoons that will fire from their body whenever they are touched. As if that wasn’t scary enough, these cells will fire their weapons quicker than we can blink. Wowza.

How does it hurt so badly?

Jellyfish don’t hold back when it comes to landing that sting. In fact, their venom can penetrate into all kinds of cells within our body. Once there, it can cause intense pain and blistering. Don’t worry if you get stung; you don’t have to go all Friends on us. Although, that does show who your true friends really are. Instead, it usually takes some vinegar and a trip to the emergency room to get you patched up.

It’s what’s inside that counts

So just what is inside a jellyfish? There are no bones, brain, or even a heart found in these creatures. In fact, many species of jellyfish are made up of around 98% water. This means if a jellyfish were to wash up on land, it would almost entirely disappear when the water evaporated. This is one of the many reasons these creatures are so tricky to capture and study.

If I only had a brain

Sure, it might seem as though some people don’t have a brain. However, jellyfish don’t at all – literally. Instead, these creatures rely on nerves at the end of their tentacles to help them detect salt levels and temperature. To keep upright, they have light-detecting cells along the edge of their bell. So how do they know how to catch prey? Well, it’s kind of down to luck. Jellyfish need creatures to swim into their tentacles if they want to eat.

No heart = no love?

Our hearts are in charge of getting oxygen all around our bodies. Sounds like a pretty important organ, right? Yup. So how does a jellyfish live without one at all? This is where they are perfectly adapted not to need a heart of their own. The ectoderm (outer layer) of a jellyfish is extremely thing meaning oxygen can merely diffuse in and out of the body without the need for a beating heart.

Indeed there is more to jellyfish than meets the eye. Although they might seem to be a terrifying creature of the deep, it looks as though these simple sea creatures really are just that – simple. Isn’t science fantastic?