Echinoderm Envenomation Clinical Presentation

Updated: Jun 01, 2022
  • Author: Scott A Gallagher, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
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Immediate and often incapacitating pain is described following puncture wounds from the crown-of-thorns starfish (Acanthaster planci), long-spined urchins (Diadema species, Echinothrix species), and some short-spined urchins (Phormosoma species). Similarly, pedicellaria-containing urchins (Toxopneustes species, Tripneustes species) and other short-spined urchins (Asthenosoma species, Araeosoma species) may deliver a severe sting at the slightest touch without inflicting any puncture at all. Significant ocular inflammation, dermatitis, and pain may follow topical exposure to the holothurin toxins of venomous sea cucumbers.

Crown-of-thorns starfish (Acanthaster planci)

Envenomation begins with penetration of the skin with the long remarkably sharp dorsal spines. Usually, but not invariably, immediate excruciating burning pain is experienced at the puncture site. Divers are reportedly at risk of unsafe ascent, disorientation, and loss of control because of the intense pain. A single puncture may result in several hours of pain, while multiple or intraarticular punctures may lead to pain, discomfort, and limitation of joint movement for several weeks.

Bleeding at the puncture site may be prolonged in some patients and is followed by surrounding ecchymosis and soft tissue swelling. Systemic symptoms of protracted nausea and vomiting, headache, arthralgias, paresthesias, and muscular paralysis are less substantiated than the other symptoms described but, nevertheless, are reported in several texts. Case reports of edema and pruritus suggest the possibility of allergic reaction, although no reports of anaphylaxis or fatality are mentioned.

Common complications result from retained foreign material and include secondary infection and granuloma formation.

Sea urchins

The mechanism of envenomation varies among the 3 groups.

Long-spined urchins (Diadema species, Echinothrix species) are capable of causing deeply penetrating injuries. Envenomation initially results in severe burning pain, which is localized to the puncture site and may last several hours, reappearing with any pressure on the wound site. Localized edema, erythema, warmth, and bleeding may follow. The systemic symptoms of nausea, vomiting, paresthesias, muscular paralysis, and respiratory distress occur in the most severe cases. Delayed sequelae include wound tattooing as pigment is leeched from dark-colored spines into the surrounding tissue, synovitis if a joint space is violated, and secondary wound infection or granuloma formation if foreign material is retained.

Some short-spined urchins have spines tipped with balloonlike venom sacs that are capable of delivering a severe sting without inflicting a penetrating wound (Asthenosoma species, Araeosoma species), while others envenom in a fashion similar to long-spined urchins, releasing venom into the wound when the spine penetrates the skin (Phormosoma species).

Urchins with pedicellaria may envenom following simple handling if sufficient contact occurs. The flower sea urchin (Toxopneustes pileolus) is reputedly the most venomous of urchins. Intense radiating pain, paresthesias, hypotension, respiratory distress, and muscular paralysis are potential sequelae of contact with this species and may last up to 6 hours. Reportedly, a female pearl diver became unconscious after accidental contact with the flower sea urchin and subsequently drowned.

Sea cucumbers

Envenomation follows contact with the toxin-containing body wall or the organs of Cuvier, a mass of white, pink, or red tubules just inside the anus. In some species, long sticky threadlike organs may be extruded from the anus when the animal is disturbed. Direct contact with these organs, or even fragments released in close proximity to a diver, may induce a papular contact dermatitis, severe ocular inflammation, and, purportedly, blindness.

Similarly, toxic mucous secretions on sea cucumber skin can be a skin and eye irritant. These toxins, known as holothurins, also are elaborated in the body wall and, thus, are capable of causing severe illness or death upon ingestion.


Physical Examination

The severity of envenomation depends on multiple factors, including the offending species; site and number of stings; the size, maturity, and age of the animal; and the underlying health and individual sensitivity of the individual exposed.

Puncture wound

In addition to immediate pain, deep puncture wounds that accompany envenomation by crown-of-thorns starfish (Acanthaster species), long-spined urchins (Diadema species, Echinothrix species), and some short-spined urchins (Phormosoma species) often are associated with retained spine fragments and persistent discomfort. Violet or black discoloration of the wound may occur as pigment from dark-spined species (Diadema, Strongylocentrotus) leeches into the wound; this discoloration usually is not permanent. Bleeding, ecchymosis, surrounding erythema, edema, and even pruritus may follow spine puncture by Acanthaster species.

Complications arise when punctures occur in proximity to a joint space (eg, synovitis), nerves (eg, neuropathy), vessels (eg, hemorrhage), or when wounds become indolent, often because of retained spine fragments (eg, chronic pain, granuloma, secondary infection).

Nonpenetrating wounds result from envenomation by some short-spined urchins (Asthenosoma species, Araeosoma species) and pedicellaria-containing urchins (Toxopneustes species, Tripneustes species). Although the local complications that follow puncture wounds do not occur, significant pain and systemic effects result.

Sea cucumber envenomations similarly are not associated with puncture wounds. Contact with the venomous tentacular organs of Cuvier or dispersed fragments may result in severe dermatitis, conjunctivitis, keratitis, and, possibly, blindness.

Systemic effects

A panoply of systemic effects has been described following echinoderm envenomations; they commonly include nausea, vomiting, paresthesias, generalized weakness, respiratory distress, and delirium. Claims of cardiac dysrhythmias, paralysis, and fatality are difficult to substantiate. The most severe echinoderm envenomations result from stings by the flower sea urchin (Toxopneustes pileolus) and have caused at least 1 death following loss of consciousness and subsequent drowning in a Japanese pearl diver.

No deaths are known to have resulted from the crown-of-thorns starfish (Acanthaster planci), although injury eventually resulting in leg amputation has been reported. Long-spined black sea urchins (thought to be Diadema species) have been implicated twice in severe neurologic sequelae, one case of meningoencephalitis and another of Guillain-Barré syndrome. The theoretic possibility of anaphylactic reaction to echinoderm venoms is entertained by some, although no cases have been documented to date.

Delayed sequelae

Delayed sequelae include chronic pain, granuloma formation, wound tattooing, and secondary infection.

Tetanus may result following echinoderm envenomations accompanied by puncture wounds.



Echinoderms are slow moving and nonaggressive; injury and envenomation occur as the result of accidental exposure or careless handling.

Bathers, waders, and divers are at risk of stepping on or being forced against the sharp spines of venomous sea urchins and starfish, especially in waters with strong surges, currents, or poor visibility.

Fishermen and overly curious individuals often become envenomed through careless handling.

The sharp spines of venomous long-spined urchins, certain short-spined urchins, and starfish can easily penetrate wet suits and gloves. The stinging tips of other short-spined urchins and those with pedicellaria easily envenomate through exposed skin.

Sea cucumbers may induce severe contact dermatitis or ocular injury in divers following unprotected handling or mask clearing in close proximity to the animal.