Moon Jellyfish

• It is recognisable by its four distinctive horseshoe-shaped gonads, visible through the translucent bell.
• It eats zooplankton, small crustaceans and fish larvae.
• It lives in temperate coastal waters and estuaries of almost every ocean in the world.
• anatomíaIt has no brain, heart or blood, and its body is more than 95% water.
• It is the most common and most recognisable jellyfish in the world, the one that turns up in any harbour: transparent, with four horseshoe-shaped gonads visible through the bell.
• Its sting is mild and most people barely notice it.
• Its life cycle has two phases: a fixed polyp called a scyphistoma, which reproduces asexually by strobilation, dividing into discs that break free as young jellyfish. A single polyp can produce dozens of jellyfish.
• And that polyp is the key to its blooms: it colonises artificial hard substrates — breakwaters, pilings, mussel rafts, ship hulls — so coastal construction provides it with exactly what it needs.
• It tolerates hypoxic, polluted waters where fish cannot hold out, which gives it an edge in harbours and degraded areas.
• It is one of the species used to study jellyfish blooms, and there are indications that it can reverse its development under adverse conditions, though not as completely as the immortal jellyfish.

Skeleton type

Invertebrate - no skeleton (gelatinous cnidarian)

Habitat and environment

Temperate coastal waters and estuaries of almost every ocean in the world, tolerating a wide range of temperature and salinity

Birth weight

Microscopic planula larva after fertilisation

Size at birth

An ephyra a few millimetres across as it breaks away from the polyp

Sexual maturity

Weeks after reaching the adult medusa stage

Gestation / incubation

~10 days as a planula larva before settling as a polyp

Litter / clutch size

Numerous eggs released continuously through the breeding medusa stage

Sources consulted: Animal Diversity Web; Dimensions.com; Study.com; Animal Diversity Web (Aurelia); PMC (microbiome strobilation study); A-Z Animals; UWI Life Sciences