Marine Animal Stings and Bites
Stingrays contain venom in spines located on the back of their tail. Injuries usually occur when a person steps on a stingray while wading in shallow ocean surf. The stingray thrusts its tail spine into the victim's foot or leg, releasing venom. Fragments of the spine's covering may remain in the wound, increasing the risk of infection.
The wound from the spine is usually jagged and bleeds freely. Pain is immediate and severe, gradually diminishing over 6 to 48 hours. Fainting spells, weakness, nausea, and anxiety are common. Vomiting, diarrhea, sweating, generalized cramps, and breathing difficulties are less common.
Because stingray venom is inactivated by heat, pain can be relieved by immersing the injured limb in water as hot as the person can tolerate for 30 to 90 minutes. A doctor cleans the wound thoroughly and removes any fragments of the spine or its covering to prevent infection. The wound may require surgical closure. Infected stingray wounds require antibiotics, and the doctor may reopen the wound to look for any retained fragments of the spines.
A few mollusks, which include snails, octopuses, and bivalves (such as clams, oysters, and scallops), are venomous. The California cone (Conus californicus) is the only dangerous mollusk in North American waters. Its sting may cause pain, swelling, and numbness in the area of the sting and may be followed by difficulty speaking, blurred vision, paralysis of muscles, respiratory failure, and cardiac arrest. The bites of North American octopuses are rarely serious. However, the bite of the blue-ringed octopus--found in Australian waters--although painless, produces weakness and paralysis that may be fatal.
First-aid measures seem to provide little benefit for injuries from Conus stings and blue-ringed octopus bites. However, these injuries may require intensive medical support because of possible respiratory paralysis.
Sea urchins are covered with long, sharp, venom-coated spines. Touching or stepping on these spines typically produces a painful puncture wound. The spines commonly break off in the skin and cause chronic pain and inflammation if not removed. Joint and muscle pain and skin rashes may develop.
Sea urchin spines should be removed immediately. Because vinegar dissolves most sea urchin spines, several vinegar soaks or compresses may be all that is needed to remove spines that have not penetrated deeply. Surgical removal may be required for imbedded spines. Because sea urchin venom is inactivated by heat, soaking the injured body part in hot water often relieves the pain.
Many coelenterates, which include corals, sea anemones, jellyfish, and the Portuguese man-of-war, have highly developed stinging units (nematocysts) on their tentacles; a single tentacle may contain thousands. The severity of the sting depends on the type of animal. The sting of most species results in a painful, itchy rash. The rash may develop into blisters that fill with pus and then rupture. Other symptoms include weakness, nausea, headache, muscle pain and spasms, runny eyes and nose, excessive sweating, and chest pain that worsens with breathing. Stings from the Portuguese man-of-war, including those that occur in North American waters, have caused death.
Most coelenterate stings require no more than cleaning. The following general treatment is suggested:
1. Pour ocean (not fresh) water over the injured area.
2. Soak the injured area in a solution of vinegar for 30 to 60 seconds. (This inactivates the nematocysts of box jellyfish.)
3. Remove the tentacles with a tweezer or a gloved hand.
4. Pour flour or baking soda over the wound and carefully scrape the powder off with a sharp knife.
5. Soak the area in vinegar again.
6. Apply an ointment containing a combination of an antihistamine, an analgesic, and a corticosteroid.
People with more serious reactions may require oxygen therapy or other assistance in breathing. Painful muscle spasms and severe pain are treated with drugs given intravenously. Antivenom is available for the stings of certain Australian species, but it is ineffective for stings of North American species.
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