What Do Jellyfish Eat? Box Jellyfish Diet, Prey and Hunting

Box jellyfish are carnivores. Their diet varies with species and size, but commonly includes small crustaceans, prawns and fish.

What does Chironex fleckeri eat?

The Australian Museum describes the large Australian box jellyfish in inshore waters where it feeds on bay-dwelling prawns. Research indicates that young C. fleckeri feed heavily on the shrimp Acetes australis, while larger individuals add fish to their diet as their bell, tentacles and venom-delivery system develop.

How box jellyfish catch prey

1. Long tentacles spread through the water as the animal swims.
2. Contact triggers microscopic stinging capsules called nematocysts.
3. Venom immobilizes small prey.
4. The tentacles contract and move the prey toward the mouth beneath the bell.

This venom evolved for feeding and defense. Human stings are accidental encounters, not deliberate attacks.

Do all box jellyfish eat the same food?

No. Cubozoa contains many species, from small four-tentacled forms to large chirodropids with multiple tentacles at each corner. Available prey changes with body size, habitat and time of day. Research on nocturnal species also shows visually guided foraging, so “they simply drift into food” is an incomplete description.

Do box jellyfish eat people?

No. Humans are not prey. A tentacle fires because of physical and chemical contact; the stinging cells do not need the animal to decide that a person is food.

Role in the food web

By consuming planktonic crustaceans and small fish, box jellyfish transfer energy through coastal food webs. Their own predators are less well documented than their prey, so broad claims that a particular animal “controls” box jellyfish populations need direct evidence.

Diet changes with body size

Life stage or type	Likely prey emphasis	Evidence question
Small juvenile Chironex	Tiny crustaceans including shrimp-like prey	Were gut contents or feeding trials used?
Larger Chironex	Crustaceans plus fish	Did venom and tentacle development change with diet?
Small mangrove carybdeids	Zooplankton and small crustaceans	Was feeding observed in natural habitat?
Nocturnal species	Prey available under low-light conditions	How did vision and activity influence capture?

From contact to swallowing

1. Tentacles encounter prey.
2. Local mechanical and chemical cues trigger nematocysts.
3. Venom and entangling structures immobilize the prey.
4. Tentacles contract and transfer food toward the mouth beneath the bell.
5. Digestion occurs in the gastrovascular cavity, distributing nutrients through internal canals.

Do box jellyfish actively hunt?

Yes, in the sense that many can swim, steer and use sensory information to remain near prey. Hunting strategy differs among a mangrove specialist, a large estuarine Chironex and an offshore Alatina. “They drift until food hits them” is too simple.

How diet is studied

• Direct field or laboratory feeding observation
• Microscopic gut-content identification
• DNA-based prey detection
• Stable-isotope analysis over longer dietary periods
• Changes in venom and tentacle anatomy during growth

Each method has bias. A soft prey item may disappear quickly, while a laboratory menu may not represent wild choice.

Food-web role

Box jellyfish convert planktonic crustaceans and fish into medusa biomass and become potential prey or detritus in turn. Quantifying that flow requires local abundance and diet data; it cannot be inferred from one dramatic feeding observation.

Frequently asked question: do they eat people?

No. Humans are not prey. Nematocysts fire through local contact cues; a sting does not mean the animal attacked or attempted to feed on a swimmer.

Sources

• Australian Museum: Box Jellyfish
• James Cook University research: prey and venom variation
• Research on visually guided hunting in a nocturnal box jellyfish

Editorially reviewed: 22 August 2026.

Explore the complete topic

Put this subject in context with our complete box jellyfish guide. To inspect the evidence behind our articles, visit the box jellyfish research and source library.

Diet-by-species evidence database

This table separates direct observations from reasonable ecological inference. “Unknown” means the evidence needed for a species-level claim has not been located—not that the animal does not eat that prey.

Filter species or prey:

Species or group	Recorded prey	Evidence	Prey-size context
Chironex fleckeri, juveniles	Shrimp-like crustaceans, including Acetes australis	Feeding and developmental research	Very small prey relative to an adult medusa
Chironex fleckeri, larger medusae	Prawns; fish are added as medusae grow	Field and laboratory evidence synthesized by Australian researchers	From small crustaceans to fish
Tripedalia cystophora	Small crustacean zooplankton in mangrove lagoons	Behavioral and habitat observations	Millimetre-scale planktonic prey
Copula sivickisi	Zooplankton associated with nocturnal, visually guided hunting	Controlled visual and field observations	Small points of bioluminescence can guide hunting
Alatina alata	Species-level wild diet remains incompletely resolved	Insufficient direct gut-content data	Unknown

Prey-size chart: what changes as a medusa grows?

Three horizontal bars show juveniles emphasizing tiny crustaceans, intermediate medusae taking prawns, and larger medusae adding fish. The chart is categorical and not a measured universal size scale.
Relative prey-size envelope—not a ruler
Juveniletiny crustaceans
Growing medusaprawns and similar prey
Large medusacrustaceans + some fish
Categories summarize published observations; prey availability and species still matter.

Illustrated hunting sequence

1. Search: active swimming and visual cues help some species remain where prey is concentrated.
2. Contact: mechanical and chemical cues at a tentacle initiate local nematocyst discharge.
3. Immobilize: microscopic tubules penetrate or entangle prey and deliver venom.
4. Transfer: tentacle contraction brings prey toward the mouth beneath the bell.
5. Digest: food enters the gastrovascular cavity and nutrients move through internal canals.

Evidence base: developmental diet research, a deep-reef Chironex field study, and nocturnal visual-hunting research.

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