Carukia barnesi: Irukandji Jellyfish Profile

Species profile · Last reviewed 22 August 2026

Carukia barnesi is a small Australian box jellyfish with an outsized medical reputation. It is the classic species linked to Irukandji syndrome, a delayed systemic illness that may follow an initially unimpressive sting. It is not, however, the only jellyfish capable of producing that syndrome.

Identification

The transparent bell is only a few centimetres tall, with one slender tentacle at each of its four corners. Small reddish structures may be visible inside a fresh animal. Those clues are not a safe field test: the animal is difficult to see in water and similar carybdeids require specialist examination.

Range and habitat

Verified records are centred on tropical Australian waters. Like many small cubozoans, its offshore and near-shore movements are not fully resolved. A general map cannot predict whether a particular beach is safe on a particular day; local marine-stinger notices are the relevant source.

Why the sting can be deceptive

The first skin sensation may be mild compared with the illness that follows. After a delay, a person can develop severe back or abdominal pain, sweating, nausea, agitation, headache and dangerous cardiovascular effects. The term “Irukandji syndrome” describes that clinical pattern, not a visual identification of C. barnesi.

What researchers still want to know

Long-term abundance, the full offshore life cycle and the environmental cues behind encounters remain active questions. Sampling tiny transparent animals is hard, and clinical cases often occur without a specimen. Good research separates a confirmed animal record from a syndrome reported in the same region.

Sources

• Australian Museum: Irukandji-associated jellyfish
• Healthdirect Australia: jellyfish stings
• World Register of Marine Species

Medical content is editorially source-checked; independent clinical review is pending.