Happy World Jellyfish Day!

Today is World Jellyfish Day, and we’re celebrating the brainless, boneless, and beautiful inhabitants of our Jelly Gallery. Let’s learn something new about jellies…

Jellyfish are ancient.

Cnidarians first appeared on the fossil record nearly 600 million years ago. Fossilised jellies are incredibly rare due to their being boneless, but the fossil record has revealed some fascinating findings.

The first evidence of cnidarian existence came in the form of polyps (juvenile-stage jellies) fossilised in rocks about 560 million years ago. While these weren’t yet fully mature jellyfish, they helped scientists to track their evolutionary history.

This finding became even more exciting when Burgessomedusa phasmiformis was discovered. This mature, free-swimming medusa lived during the Cambrian period about 500 million years ago. As the oldest macroscopic jellyfish in the fossil record, Burgessomedusa phasmiformis proves that large, swimming jellyfish with the familiar bell shape that we know today had already evolved over 500 million years ago!

Jellyfish are immortal…

No animal cheats death better than a jellyfish! Some species, like the “immortal jellyfish” (Turritopsis dohrnii), are literally named for this ability. Others, like our moon jellies (Aurelia sp.), are also capable of living forever…

The way jellies attain immortality is fascinating. If they have sustained severe damage to their bodies or their environment becomes unsuitable, adult jellyfish can revert to their juvenile form. They can go from adult “medusae” to immature “polyps” by a process of transdifferentiation. This allows adult cells to go back to stem cells that are capable of regrowing tissue – essentially, it’s “cell recycling”.

In theory - if the jellies don't become sick, injured, or eaten, they can live forever by doing this!

Jellyfish are incredibly quick.

When you’re strolling through our mesmerising Jelly Gallery, you may not think that jellyfish are particularly speedy. But you couldn’t be more wrong!

Jellyfish possess stinging cells called nematocysts that comprise small, venom-filled barbs called cnidae. Believe it or not, the process whereby these cells are fired is the quickest biological event in nature – these venomous cnidae accelerate at about 5.4 million times the force of gravity when fired! If you’re not too sure how fast that is, it’s 500 000 times quicker than the blink of an eye.

A box jelly sting can exert pressure of up to 7.7 gigapascals on its prey, which is about 350 times the pressure of an armour-piercing rifle bullet striking a hard target. As the cnidae are quite small, there is not enough force for us to feel that pressure, but it is enough to pierce the skin of most animals.

Jellyfish could be our solution to microplastics.

Microplastics are one of the biggest threats to marine life in 2024. Some studies have even found microplastics in the human heart!

But jellyfish could come to our rescue. An international collaboration called GoJelly discovered that the mucus excreted by the common moon jelly and nomad jellies can absorb tiny particles of microplastic. When the mucus sinks, the plastic is carried with it. GoJelly is working on a filter system that can harness this phenomenon in an attempt to reverse some of the plastic pollution affecting our oceans.

In a nutshell, jellyfish are amazing and more multifaceted than many realise. Come and visit our Jelly Gallery and learn even more about these awesome animals!