I was fishing in an estuary with my father a long while back when I landed a small ray of about 18 inches (45 cm) across the wings.
He immediately jumped up warning me of the barb above the tail which he had already found out about the hard way. Being venomous, it had been an extremely painful experience and the treatment that the ranger had suggested was to submerge the injury in the hottest water he could bear in order to diffuse some of the venom out of the wound.
Much to my relief my catch was diagnosed as not being the stingray variety and I was advised casually, “Its probably one of the electric jobs. You had better get the hook out of it.”
As I started removing the hook I had this incredible jar of electricity right up my arm.
Such was my introduction to rays…..
The sting-ray has its mouth situated underneath enabling it to find crustaceans and mollusks on the ocean floor. They typically stay on the ocean floor and rarely venture up. Their main defense is camouflage by hiding in the sand. This they do by flapping their wings until only their eyes and spiracles are showing. A spiracle being a respiratory opening, therefore allowing the fish to see and breath.
The sting-rays tail has a stinger which has barbs that are venomous. when threatened the stingray will position itself much like a scorpion with its tail ready to strike, the tail having between one and three barbs depending on the species. Stepping on one of these in the shallows at the beach can be a painful experience especially as the barb is inclined to break off in the wound and its difficult to extract. while its in there you are also dealing with the venom source potentially further infiltrating the wound.
With the eyes positioned above and the mouth below, one has to wonder how the prey is found. The answer lies in small electro-receptors, similar to those found in shark (which are related to stingrays). these receptors detect the presence of prey below the sand while the eyes are still able to detect any predator threat which is likely to come from above or the side.
These receptors are called Ampullae of Lorenzini and are situated around the rays mouth. Prey like shrimp and small fish that are hidden in the sand emit tiny electrical currents in the region of 2 hertz and that the stingray is able to detect through the sand.
The mouth, dependent on the species is either soft or where they consume things like mollusks, have two hard plates used for crushing the shells. These plates, along with the cartilage are the hardest part of the stingrays body as they do not have bones. This cartilage fact is another shark-type similarity.
Stingrays do not lay eggs but are live bearers having between 3 and 13 at a time. Research suspects that the same mouth receptors that detect prey may be used in finding a mate with female stingrays giving off specific signals when ready for mating.
There is no placenta in the womb but the embryos absorb nutrients from a yolk sac after which the mother provides a kind of uterine milk until birth. Once born the babies swim away from the mother and follow their instincts for survival. These babies can expect a lifespan of between 20 and 25 years, supposing they do not get predated on by sharks, seals or other large fish.
And finally, for the collective noun – group of stingrays is referred to as a ‘fever’.