A 26 y.o. male was snorkeling in Hawaii. He comes in with a rash.
What is it?
multiple punctate lesions
Our patient had a sea urchin sting which became infected.
Sea urchins are a class of echinoderms which have been present in the world’s oceans since the Permian age. They are relatively slow moving and developed small claws called pedicellaria which can inject venom for defense. Some species also developed spines. The spines are brittle and often break off when touched. The spines are also able to inject venom even when broken off in a wound. Injuries from sea urchins result both from mechanical trauma and venom.
pedicellarieae and spines contain venom; tube feet on the right are used for locomotion
The clinical manifestations of are intense burning at the site, discoloration from the spine and the venom which leaves a dark purple spot.In severe cases there can be respiratory distress and even paralysis from a anti-cholinesterase inhibitor in the venom which causes a build up of acetylcholine and muscle paralysis.
The most common envenomation in Hawaii is from the long spine sea urchin where the venom is concentrated in the shorter spines.
long spined Hawaiian sea urchin
The deadliest sea urchin envenomation is from the flower urchin found throughout the Indo-Pacific ocean. The venom causes severe pain, muscular paralysis and disorientation. Breathing problems result in accidental drowning.
note the tube feet on the bottom of the flower urchin
TREATMENT
Remove as many spines as possible with sea water and scraping them off.
Flush the area with hot water.
Use vinegar to help dissolve attached spines.
Prevent infection -Wash with soap and water. Be aware that parts of the spines may still be embedded and would need to be removed surgically. Common organisms that cause infection are Vibrio alginolyticus, Vibrio vulnificus and Staph/Streip species driven in from the skin.
FUN FACTS
There are many more venomous organisms in the ocean. Four venomous fish species include: stonefish, box jellyfish, lion fish and scorpionfish.
Of these the deadliest are box jellyfish which can cause cardiac arrest , respiratory failure and death in minutes.
Our patient failed to respond to penicillin and cephalosporin. Extensive debridement was done. and antibiotics changed to sulfa and gradually recovered. He grew out Vibrio alginolyticus.
Gelman Y, Kong E, Murphy-Lavois H. Sea urchin toxicity. StatPearls Treasure Island (FL): StatPearls Publishing; 2026 Jan
Chemical Defense in Marine Organisms, 3rd Edition)
https://scubadiverlife.com/four-marine-life-injuries-treat/
Bultmann C, Steiss J, Langner C et al. Complicated sea urchin-induced wound infection caused by Vibrio aginolyticus. JMM case reports 2015 Dec 19;3(6):3 005074.
Ehlert-Flaskamper S, Morri C, Harris R. Prickly defenders: a review of venomous sea urchins. Mar Drugs. 2025 Jun 13;23(6):253.