Steve Irwin’s
sad death has generated hundreds of emails to Elasmodiver requesting
information about stingrays and stingray barbs. Rather than try to answer
them all individually I have created this page that covers most of the
questions that people have been asking:
What do
Stingray use their barbs for?
Stingrays
use their barbs (also known as tail stings or tail spines) as defensive
weapons to protect themselves from sharks and other predators. However,
rather than risk potentially dangerous confrontations they generally swim
away when approached by divers or other large animals. Using their barbs
to attack is definitely a last resort.
Do
Stingrays use their barbs when feeding?
They do not
use their barbs to kill their food because their diet generally consists
of invertebrates that live under the sand or mud. They dig in the sand
and suck up their lunch sometimes crushing it between their flat,
plate-like rows of teeth.
How
exactly does a stingray use its barb?
The
Stingray jabs forwards with its tail held over its head like a scorpion.
Threat displays have been witnessed in which a stingray held its tail
aloft while it was receiving close attention from a shark. Great
hammerheads (a major predator of stingrays) have been found with as many
as fifty spines lodged in their throats.
What is
a stingray’s barb made of?
Stingray
skin is covered partially in dermal denticles (literally ‘skin teeth’)
that contain dentine just like normal teeth. They look like short pointed
spikes when viewed under a microscope. The ray’s tail spines are modified
dermal denticles that have become elongated so that the can be used as
defensive weapons.
Are
stingray barbs poisonous?
The
Stingray's barb is covered in a mildly venomous sheath of skin. When the
barb is pushed into a foreign body the venom is dispersed. The venom
consists of a
protein based toxin that causes a lot of pain in the area of the wound and
may also alter the heart rate and affect the respiration in a victim.
How do
you treat a wound from a stingray barb?
The wound
should be immersed in the warmest water that the victim can stand. This
will immediately start to break down the toxins and alleviate much of the
pain. Once the pain has been brought under control the wound should be
irrigated to ensure that no fragments from the stingray barb remain.
Secondary infection is common and a physician may recommend antibiotics to
avoid complications.
What
happens to the Stingray after it loses its tail spine?
If the
stingray loses one of its barbs while defending itself, it immediately
begins to grow a new one. Stingrays shed and re-grow their spines on a
regular basis regardless of whether they use them.
How many
spines do stingrays have?
Depending
on the species, stingrays may have up to 7 or more spines although most
have one or two and some have none at all.
What
types of rays have tail barbs?
Families of
rays that possess tail spines include Butterfly Rays, Whiptail Stingrays, Round Stingrays,
River Stingrays, Eagle Rays, Cownose Rays, and Mobula Rays.
How
common are injuries and deaths from stingray barbs?
Very rare!
There are very few records of stingrays killing humans and when these
cases do occur the actual cause of death is usually secondary infection
not the wound itself. The most common victims are beach and river
fishermen and others who spend a lot of time wading in shallow water.
Stingrays are greatly feared in the Amazon River where stingray wounds are
relatively common and expert medical attention may be difficult to get.
How can
you avoid being wounded by a stingray?
Again, the
chances of a beachgoer being stung are very small but there are a few
things that you can do to lessen the chances even further. Stingrays
attack when they are pinned down and unable to swim away. If you shuffle
your feet instead of taking raised steps you are less likely to trap any
stingrays that are lying buried under the sand.
Divers
should avoid cornering rays (or any dangerous animals) against the reef or
swimming directly over them as this could be perceived as a threat.
Since the
tragic incident with Steve Irwin there have been reports of reprisals
against stingrays involving fishermen cutting off their tails and leaving
them to die. Not only is this practice barbaric, if it gets out of control
it will upset the balance of the environment. Stingrays are very vulnerable
because they reproduce slowly and have much fewer offspring than bony
fishes.
Stingrays
(like sharks) play an important role in keeping the numbers of invertebrate
animals in check. If the rays are wiped out from a particular area the
entire localized ecosystem will begin to change. Imagine what a plague of
snails could do to a reef if there were no stingrays to keep their numbers
down.
Stingrays
have a right to defend themselves but they are generally gentle and timid.
They are extremely graceful creatures that appear to ‘fly’ through the water
like giant birds and the world would be a lesser place without them.