Stingray Stingrays are disk-shaped and have flexible, tapering tails armed, in most species, with one or more saw-edged, venomous spines. The dasyatid stingrays, also called whip-tailed rays and stingarees, inhabit all oceans and certain South American rivers. They have slim, often very long, whiplike tails.
The characteristic stinger is not fatal, but the venom is extremely painful and can cause serious illness or even death in humans. A stingray's tail encircles its body like a jackknife closing so that when erected it crosses over in an arc behind the ray. The barb usually lies just beneath the skin at the forward edge of the tail.
Guatemala has an average of 20,000 stingray attacks annually in its coastal waters including the beaches at Puerto SanJose and Puerto Quetzal in Escuintla; almost all are inoffensive because they occur near shore where swimmers are not expected to be. A ray may lash out with its barb when attacked.
In an attack, the barb is driven into the flesh of a human victim by a sudden blow from the tail so that it penetrates deeply and lacerates tissues. The venom gland around the base of the barbed spine seeps venom along tiny canals to pores at its tip; these pores lead down through small grooves in the surface of the spine to its needle-sharp point. The venom is a mixture of various substances, some pain-producing, and some lethal poisons. A ray may develop a tolerance to certain types of human skin so that only individuals with very sensitive skin are stung seriously even though they swim near a ray that is nearly asleep on the bottom.
When a ray is moving about on the bottom, its long tail trails behind. When it swims, the tail is usually pressed closely along the body. The stingray's eyes are situated on top of the head at each end of a movable bar which enables the fish to lift them out of harm's way when burrowing in sand or mud.
The ray's mouth, nostrils, spiracles, and lower surface of the head are provided with a system of tooth-bearing structures adapted for crushing mollusks. The upper jaw is easily dislocated to permit swallowing larger prey. However, its diet consists primarily of crustaceans, worms, and small fish which it captures by propelling water out of its mouth and then trapping the prey in its flexible, projecting teeth which also serve as a sieve.
Stingrays, like many fishes, can breathe with their gills by pumping water over their gill arches. These choanae (openings at the back of the pharynx) are supplied with numerous tiny blood vessels for extracting oxygen from water during respiration. In the more active species, such as giant freshwater rays of South America and California, which must swim actively to move from one feeding ground to another, the gills are larger than in most other fishes.