The first thing you need to know about jellyfish is that they aren't fish. You probably knew that already but do you know what they actually are? Well I didn't either, but they're a type of zooplankton which means they're an animal that spends its whole life suspended in the water. They belong to the same animal group as sea anemones and corals.

They have a rudimentary nervous system comprising ganglion (nerve) cells throughout their bodies, and they can sense light, chemicals and movement which is how they know there is prey nearby and can catch it. Most of them are passive carnivores; they eat creatures they bump into, rather than actually chase them. Their prey is mainly other plankton, crustaceans,and small fish which they stun or kill with the toxin from their tentacles.

Jellyfish consist of only six organs: the gastrodermis lines the gastrovascular cavity which is where food is taken in and absorbed; then there's the mesoglea (jelly) wrapped in the epidermis (through which they absorb oxygen from the surrounding water – they have no lungs). Then they have a manubrium (mouth) and tentacles. The jelly contains collagen, for which they are harvested for use to treat rheumatoid arthritis as well as in cosmetic surgery. In some parts of the world, notably East Asia, certain species are a delicacy and caught for food. There's even a company investigating using mucus from a particular jellyfish as part of a filter to remove microplastic particles from the oceans. Wouldn't that be cool if it works!?

It's believed that jellyfish have been around for 650 million years or so, and are the oldest multi-organ animal. They thrive in every ocean on this planet – yes, so you will even find them on our Cumbrian coast, the most common being lion’s mane, barrel, moon and compass jellyfish. Different stages of the jellyfish reproduce by different means; the initial (polyp) stage can form clones of itself which drift off and eventually mature into medusae (the tentacled adults). Once they're adults, they release clouds of eggs or sperm into the water to fertilise.

Their stinging cells are called nematocysts and their firing mechanism (when they sting something) is the fastest propulsion known on Earth – even faster than a bullet from a gun. All in all, for something we think of as an annoying – and often painful – drifting blob, they're pretty amazing!

Find out more about jellyfish and other amazing marine wildlife at Living Seas North West is a partnership of the North West Wildlife Trusts which works hard to protect wildlife in our Irish Sea.