Did you know ... jellyfish are not fish?

One of my favourite marine creatures, jellyfish are hypnotic, mysterious, fascinating.

Long time ago, I went to Sea Life specifically because they were having a new jellyfish exhibition which promised an out-of-this-world experience. It didn’t disappoint.

I remember entering into a very dark room. There were different tanks of different shapes (most of them cylindric, though) and sizes containing different species of jellyfish. There were lots of them. They were all beautiful, like magical creatures, or creatures from outer space.

I stayed there, observing and learning about them for a few hours. They made me feel relaxed, calm, and also made me wonder about the deep-sea species we don't know much about or we don't know anything at all. The way jellyfish move is hypnotic and so it is their luminescence. Jellyfish are beautiful, rather special creatures. However, they are not fish.

The fascinating world of sea jellies (known as jellyfish)

The fact is, jellyfish are not fish. To avoid confusion, they are also called sea jellies due to their jelly-like appearance. Sea jellies (or jellyfish) are made of 90% percent water.

Jellyfish are mysterious, fascinating, beautiful marine creatures that have been roaming the ocean for hundreds of millions of years.

Scientists have uncovered evidence about jellyfish that have been living in the ocean for at least 500 million years. It’s likely that their lineage goes back even as far as 700 million years or even longer. That makes them almost three times older than the first known dinosaurs.

There are over 2,000 known species of jellyfish. However, scientists believe there could be around 350 thousand different species of jellyfish yet to be discovered.

Some jellyfish are clear, but others are vibrant colours such as pink, yellow, blue, and purple. They can be bioluminescent, too, which means they produce their own light.

Jellyfish have no brain, heart, blood, bones, or eyes. They are made up of a smooth, bag-like body and tentacles armed with tiny, stinging cells that they use to protect themselves.

However, jellyfish can feel and feel pain since they have an elementary nervous system with receptors that detect light, vibrations, and chemicals in the water. This, along with their sense of gravity, allow jellyfish to display great orientation and navigate in the water with purpose and direction.

Indeed, jellyfish do respond to their environment. They have a flight response which means they swim away from potential danger and toward food.