Beautiful and infamous: the flower urchin is cloaked in hundreds of pink-and-white flower-like pedicellariae that deliver one of the most dangerous stings in the sea — Guinness World Records named it the most dangerous sea urchin. It is occasionally imported, but it is a serious safety hazard and is NOT recommended for typical home aquariums.
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Educational only. KinStation content is reviewed by licensed veterinarians but cannot replace an in-person exam. Always consult a licensed veterinarian or board-certified specialist for diagnosis, treatment, or any decision affecting your pet's health.
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Test up to about 15 cm (6 in); short spines hidden under dense, flower-like venomous pedicellariae.
Lifespan
3–5 years
Social needs
solo
Native region
Indo-West Pacific (Red Sea and East Africa to Japan, Australia and the Cook Islands)
Origin
Old World
Climate
🌴 Tropical
Water type
🌊 Marine
Family
Toxopneustidae
Genus
Toxopneustes
Part of the Sea Urchins
Spiny echinoderm grazers prized as reef clean-up crew for mowing down film, hair and nuisance algae. Most are reef-safe but may dislodge loose corals, and all are highly intolerant of copper and sudden salinity changes.
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Larva
Most marine invertebrates hatch into microscopic planktonic larvae (such as the zoea of crustaceans or the bipinnaria/veliger of echinoderms and mollusks) that drift and feed in the water column. The larva looks nothing like the adult and undergoes major reorganization.
Photo coming soon
Juvenile
After settling out of the plankton, the juvenile takes on a recognizable miniature of the adult body plan — a tiny shell, a small star, or a translucent shrimp. Crustaceans grow by molting, shedding the exoskeleton to enlarge.
Photo coming soon
Adult
Adults reach full size and reproductive maturity with the species' mature shell, shape, or coloration. Many continue to molt or grow throughout life, and some show sex differences in size or claw/appendage shape.
Color & pattern variants
Natural variants occur in the wild; selectively bred (man-made) variants were developed in captivity.
Natural
Pink & White (typical)
The classic look: a dense carpet of pink-and-white flower-like pedicellariae over the test. Coloration varies but the 'flower' armament is diagnostic — and venomous.
Habitat & enclosure
This is a wild Indo-West Pacific reef and seagrass animal that adapts poorly to home tanks and endangers anyone working in them; the encyclopedia documents it for identification and safety rather than as a recommended pet. If kept at all — only by experienced specialists in a dedicated, clearly-labeled, child-free system — it needs a mature marine tank with stable reef parameters (temperature 72-80F / 22-27C, pH 8.1-8.4, salinity SG 1.024-1.026, low nitrate), abundant live rock, and strict handling protocols.
Its natural range runs from the Red Sea and East Africa to Japan, Australia and the Cook Islands, where it grazes shallow reefs and seagrass, often covering itself with debris.
Substrate
If housed by a specialist, a live-rock aquascape with sand provides grazing surface; the practical requirement is a sealed, clearly-hazard-labeled tank and a strict no-bare-hands rule, not any special substrate.
Equipment & setup
Standard reef equipment (skimmer, live-rock biofiltration, heater, moderate flow) would suffice biologically. The critical 'equipment' is safety gear: long thick gauntlets, tongs, a lid, hazard labeling, and a sting first-aid/emergency plan.
Diet
A grazing omnivore that eats algae, organic detritus and encrusting organisms such as bryozoans. In captivity it would graze film algae and accept nori, but feeding is the least of its challenges compared with the handling danger.
Behavior & temperament
Slow-moving and otherwise unremarkable in behavior, often decorating itself with shells and rubble. The danger is its defensive armament: the test is covered in globiferous pedicellariae — tiny three-jawed 'flower' pincers — that clamp onto skin and inject venom. It is not aggressive, but any contact, including routine tank maintenance, risks envenomation.
Health
EXTREME HAZARD — the pedicellariae inject venom containing toxins such as Contractin A and peditoxin. Stings cause immediate, severe pain, swelling, and in serious cases muscle paralysis, respiratory difficulty, disorientation and a drowning risk for divers; medical attention is warranted. NEVER touch it bare-handed or reach into a tank housing it without planning; the pincers can stay attached and keep envenomating after detaching. It is unsafe around children, and is genuinely dangerous to the keeper, which is why it is not recommended despite occasionally appearing in the trade. For the animal itself, the usual echinoderm sensitivities apply: no copper, no air exposure, no rapid salinity swings. (Educational and safety information only — not medical advice; seek emergency care for any sting.)
Tips, DIY & hacks
Best advice for nearly everyone: do not buy it. If you encounter one in the trade or the wild, do not handle it. Specialists who keep it must treat it like venomous livestock — never bare hands, always tongs and gauntlets, warn everyone in the household, and have an envenomation emergency plan ready (it can be a medical emergency).
Reviewed and signed off by: KinStation Editorial — pre-launch draft (pending DVM review) on 2026-06-09