Moon jelly

Aurelia aurita

The moon jelly is a soft, see-through animal whose round bell glows like a moon underwater. It has no brain, heart, bones, or true fish parts, yet it senses and survives in seas around the world.

Not a fish · an aquatic neighbor

Water

Saltwater + Brackish

Coastal and open marine water, especially temperate and tropical bays, harbors, and seas.

Temperature

9–26°C · 48–79°F

A broad observed temperate-to-tropical range; Aurelia species and local populations differ.

Size

Often 15–30 cm (6–12 in) across the bell

From dessert-plate to dinner-plate size

Lifespan

The swimming medusa usually lives for months; the polyp stage can persist longer

Life expectancy varies with place, conditions, and what scientists have been able to observe.

01 · Signature adaptation

What does it do?

Moon jellies pulse their bells but are carried largely by currents. They can gather into large swarms where food and water conditions concentrate them.

Its superpowerA rhythmic squeeze of its bell pushes water backward and moves the jelly forward.

02 · Home coordinates

Where does it live?

Widely reported in temperate and tropical seas, although look-alike Aurelia species make exact boundaries difficult to map.

Regions: Atlantic Ocean · Pacific Ocean · Indian Ocean · Many coastal seas

03 · The menu

What does it eat?

Fine tentacles and sticky mucus collect tiny drifting animals and move them toward the mouth.

Plankton eater: zooplankton, tiny crustaceans, fish eggs, small larvae.

04 · Remember this

Two wow facts

Mostly water

About 95 percent of a moon jelly’s body is water, helping its delicate bell stay nearly transparent.

Sources [1]

Many shapes in one life

A moon jelly changes from a tiny swimming larva to a stuck-down polyp, then releases young jellies that grow into adults.

Sources [1] [2]