Moon Jellyfish: Facts, Habitat & More

Delicate. Hypnotic. Almost otherworldly.
With their glowing, translucent bells and slow, rhythmic movement, Moon Jellyfish are one of the most recognisable species in the ocean and one of the most mesmerising to watch.

At SEA LIFE Sydney, you can get up close to these gentle drifters and see their subtle beauty in detail, from their soft, undulating forms to the four glowing rings at the centre of their bell.

👉 Book your visit now to meet Moon Jellyfish face-to-face and discover the fascinating secrets behind their simple yet ancient design.

Book Now

Get to know the Moon Jellyfish

Mesmerising and mild, the Moon Jellyfish floats with grace. Its translucent bell, soft pulsing movement, and delicate form make it one of the ocean's most enchanting drifters.

Scientific Name

Aurelia Aurita

Habitat

Temperate coastal waters across Australia & worldwide

Size

Up to 40cm wide

Lifespan

Around 6 months in the wild

Diet

Zooplankton, crustaceans, fish eggs, and larvae

Sting

Mild sting - typically harmless to humans

Look for four rings inside the bell – these are the Moon Jelly’s reproductive organs (gonads), and they’re usually a soft pink or purple.
Their bell is pale and see-through, often with a bluish or pink tinge depending on their diet. It thins out at the edges, giving them that classic saucer shape.
Short tentacles fringe the rim, helping them sense movement and gently guide food toward their mouth.

Ancient Ocean Survivors

Moon Jellyfish have existed for over 600 million years, predating dinosaurs.
They’ve survived multiple mass extinctions thanks to their simple, adaptable design.
Today, you’ll still find them in coastal waters around the world, including around Sydney.
They thrive in bays, harbours, and estuaries, often drifting with ocean currents.

💡Why have Moon Jellyfish survived so long?

Their simple bodies, low oxygen needs, and ability to reproduce in tough conditions have helped them outlive dinosaurs and survive mass extinction events.

How They Move and Feed

Moon Jellyfish move with a gentle pulse of their soft bell — but most of the time, they simply drift with the ocean’s currents.
They feed by trailing their fringe of tentacles, which are coated in sticky mucus and stinging cells (called nematocysts). These help trap tiny prey like:

Zooplankton
Fish larvae
Fish eggs

Their sting is so mild, most humans can’t feel it at all.

Anatomy 101

Moon Jellyfish don’t have a brain, heart, or lungs — yet they’re perfectly adapted to ocean life.

Breathing? They absorb oxygen directly through their skin.
Eating and... everything else? They use a single opening for both food and waste.
Thinking? No brain here — they rely on a simple nerve net to respond to their surroundings.

💡Despite their simplicity, Moon Jellies are incredibly efficient ocean drifters.

Reproduction and Life Cycle

From tiny larvae to graceful drifters, Moon Jellyfish go through an incredible transformation:

Egg + sperm released
Adult jellyfish (medusae) release eggs and sperm into the water.
Fertilised larvae drift
These free-swimming larvae (called planulae) float until they find a surface to settle on.
Settling into polyps
Once attached, the larvae turn into stalk-like polyps on the seafloor.
Budding baby jellies
Each polyp can clone itself and bud off stacks of tiny jellies called ephyrae.
Growing into medusae
These ephyrae grow into adult Moon Jellyfish - and the cycle starts again.

💡 When conditions are right, a single Adult Moon Jellyfish can release up to 400,000 offspring during its reproductive phase

However, only a tiny fraction survive to adulthood due to predation, environmental stress, and competition.

Who Eats Moon Jellies?

Despite their delicate appearance, Moon Jellyfish are a vital food source for several marine species.

Sea turtles, especially Leatherback Turtles, are their most iconic predators.
Ocean sunfish (Mola mola), some seabirds, and even larger jellyfish also feed on them.
Because Moon Jellies are made up of around 95% water, predators must consume large quantities to meet their energy needs.

💡Leatherback Turtles may eat more than 100 Moon Jellies a day just to meet their energy needs.

Fun Facts

In 1991, Moon Jellyfish were sent into space aboard the Space Shuttle Columbia to study gravity effects.
Their colour can change based on diet; feeding on brine shrimp can turn them orange.
Source: Monterey Bay Aquarium
A group of jellyfish is called a “smack”, and large gatherings are known as “blooms”.
Source: Australian Geographic

Where to See Moon Jellyfish

Visit the Jellyfish Zone at SEA LIFE Sydney Aquarium to witness Moon Jellyfish up close, glowing under special lighting and drifting gracefully through the water.

Plan Your Visit

🪼 Ready to come face-to-bell with the magical Moon Jellyfish?

Glide into SEA LIFE Sydney Aquarium and explore the calming, otherworldly world of these translucent drifters - just one of many incredible species waiting for you under the sea.