Stingray injuries are caused by the venomous tail spines or stingers of rays
in the order Myliobatiformes, most significantly those belonging to the
families Dasyatidae, Urotrygonidae, Urolophidae, and Potamotrygonidae.
Stingrays generally do not attack aggressively or even actively defend
themselves. When threatened, their primary reaction is to swim away.
However, when attacked by predators or stepped on, the stinger in their tail is
whipped up. This is normally ineffective against sharks, their main predator.
Depending on the size of the stingray, humans are usually stung in the lower
limb region. Stings usually occur when swimmers or divers accidentally step on
a stingray, but a human is less likely to be stung by simply brushing against
the stinger. Surfers and those who enter waters with large populations of
stingrays have learned to slide their feet through the sand rather than taking
steps, as the rays detect this and swim away, as will stamping on the bottom as
one treads through murky water. . The stinger usually breaks off in the wound.
This is not fatal to the stingray as it will be regrown at a rate of about 1.25
to 2 centimetres per month. Contact with the stinger causes local trauma, pain,
swelling, and muscle cramps from the venom, and possible later infection from
bacteria or fungi. Immediate injuries to humans include, but are not limited to:
poisoning, punctures, severed arteries and veins, and occasionally death.
Fatal stings are very rare, but can happen, famously including Steve Irwin.
In this case, the stinger penetrated the thoracic wall, causing massive trauma.
Biological structure of the barb The barb is covered with rows of sharp
flat spines, composed of vasodentin. Vasodentin is an incredibly strong
cartilaginous material which can easily cut through flesh. The undersides of the
spines contain two longitudinal grooves which run along the length of the spine
and enclose venom-secreting cells. Both the venom-secreting tissues and
vasodentin are enveloped in an epidermis that tears open when the barb is plunged
into a victim. Some spines may break off as the barb exits the wound and stay
within the victim causing prolonged envenoming.
Sting Many victims of stingray related
injuries suffer from physical effects including nausea, vomiting, diarrhea,
extreme pain at the wound, muscle cramps, and a laceration at the puncture
site. There have been cases of severe consequences which may include embedded
spines, infection, hypotension, and even possible amputations or death. Stingray
wounds have also been found to bleed profusely and for a long amount of time
after the initial puncture. It has been suggested that there may be some sort of
anti-hemoglobin agent incorporated with the secreted venom, but Professor James
H. Diaz of Louisiana State University has refuted that theory.
Treatment Treatment for stings may include
application of hot water, taking care not to cause burns), which can help ease
pain by denaturing the complex venom protein. Antibiotics may be administered
to prevent infection if there is a delay in treatment, if the wound is deep, or
if there is a large amount of foreign material in the wound. Immediate
injection of a local anesthetic in and around the wound, or a regional nerve
blockade, can be helpful, as can the use of parenteral opiates such as
intramuscular pethidine. Local anesthetic may bring almost instant
relief for several hours. Vinegar and papain are ineffective. Pain normally
lasts up to 48 hours, but is most severe in the first 30–60 minutes and may be
accompanied by nausea, fatigue, spreading cramps, headaches, fever, and
chills. All stingray injuries should be medically assessed; the wound must be
thoroughly cleaned, and surgical exploration is often required to remove
any barb fragments remaining in the wound. Following cleaning, an ultrasound
is helpful to confirm removal of all the barb fragments. Not all remnants are
radio-opaque; x-ray radiography imaging may be helpful where ultrasound is not
available. See also
Snake bite Skin lesion
Steve Irwin Findlay E. Russell
Odysseus Acanthoplex References