Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Stingray Catastrophe: Steve Irwin, 1962-2006

We are saddened by the untimely death of Steve Irwin, who was killed by a stingray on September 4, 2006. As it has been reported, Steve was filming a segment for a series entitled “Ocean’s Deadliest” at Batt reef off the coast of northeastern Queensland, Australia. While in the water, he closely approached a stingray, which struck him in the left side of his chest with the venomous barb attached to its tail. He is reported to have pulled the detached barb from his chest, then to have died. According to the treating physician, the wound likely penetrated Steve’s heart. It is not determined at the time of this writing whether the cause of death was bleeding (blood loss), compression of the heart because of blood trapped within the fibrous lining around his heart (pericardium), fatal disruption of the heart’s rhythm from the shock of penetration and effects of the venom, a heart attack, or some combination of these.

Stingrays are wild animals, and while they usually make every effort to flee encounters with perceived predators, they will sometimes act in defense, by striking out with their tails in order to cause injury with the attached stinger(s). Under no circumstances should anyone assume that a stingray approached in the wild is “tame,” even if it has been habituated to the presence of humans. What follows is a brief medical tutorial on stingrays, adapted from a chapter about hazardous marine animals in the forthcoming edition of the textbook Wilderness Medicine:

The stingrays are the most commonly incriminated group of fish involved in human envenomations. They have been recognized as venomous since ancient times, known as “demons of the deep” and “devil fish.”

It is likely that at least 2000 stingray injuries take place each year in the United States. At least that many more occur in coastal waters worldwide. Most attacks occur during the summer and autumn months, as vacationers venture into the surf that may be laden with rays.

Stingrays are usually found in tropical, subtropical, and warm temperate oceans, generally in shallow (intertidal) water areas, such as sheltered bays, shoal lagoons, river mouths, and sandy areas between patch reefs. Although rays are generally found above moderate depths, at least one deep sea species has been discovered. Rays can enter brackish and fresh waters, as well. For instance, freshwater stingrays are common in rivers and tributaries in South America.

photo stingray courtesy of Howard Hall
Stingrays are small (several inches) to large (up to 12 feet by 6 feet) creatures observed lying on top of the sand and mud or partially submerged, with only the eyes, spiracles, and part of the tail exposed. Their flattened bodies are round , diamond , or kite shaped, with wide pectoral fins that look like wings. These ripple or flap to propel the animal through the water. Rays are nonaggressive scavengers and bottom feeders that burrow into the sand or mud to feed on worms, mollusks, and crustaceans.

The venom organ of stingrays consists of one to four venomous stings on the dorsum of an elongate, whiplike “tail.” In some species, the sting may be in excess of 12 inches. The efficiency of the apparatus is related to the length and musculature of the tail and to the location and length of the sting. Eagle rays and some mantas have a stinging apparatus, but it is less of a threat because the spine is located at the base of the tail and is not well adapted as a striking organ. A stingray “hickey” is a mouth bite, created by powerful grinding plates, that produces superficial erosions and bruising in an oral pattern. Persons who hand feed stingrays may incur this type of injury, as well as lose parts of fingers.

In all cases, the venom apparatus of stingrays consists of a bilaterally retro-serrated spine or spines and an enveloping skin tissue sheath. The spine is firmly attached to the top of the tail (whip) is edged on either side by a series of sharp rear-facing serrations. Along either edge on the underside of the spine are the two grooves, which house the venom glands. The entire spine is encased by the skin tissue sheath. The sting is often covered with a film of venom and mucus.

photo of stingray spine in foot by Robert Hayes
photo of stingray spine in foot by Robert Hayes
Stingray “attacks” are purely defensive gestures that occur when an unwary human handles, corners, too closely approaches, or steps on a creature while wading in shallow waters. The tail of the ray reflexively whips upward and accurately thrusts the spine or spines into the victim, producing a puncture wound or jagged cut. The sheath covering the spine is ruptured and venom is released into the wound, along with mucus, pieces of the sheath, and fragments of the spine. On occasion the entire spine tip is broken off and remains in the wound.

A stingray wound from a spine puncture is both a traumatic injury and an envenomation. The former involves the physical damage caused by the sting itself. Because of the serrations and powerful strikes, significant cuts can result. Secondary bacterial infection is common. Most injuries occur when the victim steps on a ray; another common cause is handling a ray during its extraction from a fishing net or hook. The lower limbs, particularly the ankle and foot, are involved most often, followed by the upper limbs, abdomen, and chest. In a rare case, the heart may be directly injured. There have been two reported cases of survival following cardiac injury.

The envenomation classically causes immediate local intense pain, swelling, and sometimes bleeding. The pain peaks at 30 to 60 minutes, and may last for up to 2 days. The wound is initially dusky or bluish and rapidly progresses to redness and a bruised appearance. Blood-filled blisters resembling a severe thermal burn or frostbite may occur, and may be worsened by overzealous therapeutic hot water immersion (see below). Delayed healing seen following stingray injuries is usually attributed to direct venom toxicity and infections.

A person stung by a stingray may show weakness, nausea, vomiting, diarrhea, sweating, dizziness, rapid heart rate, headache, fainting, seizures, groin and armpit pain, muscle cramps and quivering, generalized swelling, paralysis, low blood pressure, abnormal heart rhythms, and on rare occasion may die. The paralysis may represent spastic muscle contractions induced by pain, which are a tremendous hazard for a diver or swimmer.

The success of therapy is largely related to the rapidity with which it is undertaken. Treatment is directed at combating the effects of the venom, alleviating pain, and preventing infection:

As soon as possible, the wound should be soaked in nonscalding hot water to tolerance (upper limit 45° C [113° F]) for 30 to 90 minutes. During the hot water soak (or at any time, if soaking is not an option), the wound should be inspected for any readily removable pieces of the sting or its sheath, which would continue to envenom the victim. No folk remedy, such as the application of macerated cockroaches, cactus juice, “mile a minute” leaves, fresh human urine, or tobacco juice, has been proven effective. However, application of the cut surface of half a bulb of onion directly to the wound has been andecdotally reported to decrease the pain and perhaps inhibit infection after a sting from the blue spotted stingray. Although the standard recommendation is to remove the sting as soon as possible (to limit the extent of envenomation), if it has acted as a dagger deeply into the chest, abdomen, or neck (this is extremely rare) and may have penetrated a critical blood vessel or the heart, it should be left in place (if possible) until the victim is brought to a controlled operating environment where emergency surgery can be performed to control bleeding that may occur upon its removal.

Pain control should be initiated during the first soaking period. If the pain is severe and persistent, a physician may need to administer narcotics, inject the wound with a local anesthetic, or apply a nerve block. If the wound is more than very minor, the treating doctor may administer an antibiotic, then observe the victim for a few hours in order to detect any deterioration in the person’s condition. The doctor may also order x-rays or special imaging studies, such as an MRI (magnetic resonance imaging), to locate any suspected retained pieces of spine.

Prevention of stingray injuries is very important. As mentioned above, the animals should be given a wide berth and never handled or approached closely. A stingray spine can penetrate a wet suit, leather or rubber boot, and even the side of a wooden boat; therefore a wet suit or pair of athletic sneakers is not adequate protection. Persons walking through shallow waters known to be frequented by stingrays should shuffle along and create enough disturbance to frighten off any nearby animals.

To Steve Irwin’s family, I offer my heartfelt condolences. It is no consolation to his wife and children that death from a stingray envenomation is a highly unusual event, as they have lost a husband and father.

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Tags: Bites & Stings

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.