Why do jellyfish strand?


For most us, the jellyfish we see are lying on the beach. Unless we are divers or snorkellers, we don't see jellyfish swimming in the sea.


Sadly for jellyfish, once they have standed on a beach, their swimming days are well and truly over.


What happens when jellyfish get beached?


Sometimes, however, it is not just one or two that we see on the beach but hundreds or thousands.What causes them to strand like this?

It is not unusual to find a single jelly stranded on a beach, like this barrel jellyfish. They can be fascinating to see.


An onshore wind

Jellyfish are not strong swimmers and so at times,have not choice but to follow prevailing currents and winds. An onshore wind can literaly blow hapless jellyfish onto the beach.

These By-the-Wind Sailors are named very appropropriately. They literally have a sail but no fins or tail to propel themselves.They thus go where the wind takes them.Sometimes, like above, the wind them blows them straight onto the beach, and there is nothing the By-the-wind sailors can do about it.




Jellyfish often move in large groups known as blooms. This means that a current or wind affecting one jelly, can affect a large number.


Population deaths


Factors such as a change in sea temperature can affect an entire bloom of jellies, perhaps killing hundreds at a time. These may then be washed up on the beach en masse.


Jo-Anna photographed this enormous number of
sea gooseberries in Llandudno in May.

Are stranded jellyfish dangerous?


Any jellyfish that gives a sting that can be felt through human skin when it is encountered in the sea, can potentially give the same sting when it is lying stranded on the beach.






It is also worth keeping dogs away as some will try to eat as many as they can, just for the sheer fun of it (!) and this makes some dogs sick.


One of the main dangers, however, is the sheer slipperyness of a beach lined with jellies. Running along a beach deepin a daydream one day, I quickly came a cropper. You know when Scooby Doo runs on ice,and suddenly he is suddenly a mess of rotating legs? That's what I was like as I desperately tried not to fall flat on my face.