Misplaced Pages

Revision as of 01:17, 28 October 2005

Template:Taxobox begin Template:Taxobox image Template:Taxobox begin placement Template:Taxobox regnum entry Template:Taxobox phylum entry Template:Taxobox classis entry Template:Taxobox subclassis entry Template:Taxobox ordo entry Template:Taxobox familia entry Template:Taxobox end placement Template:Taxobox section subdivision Dasyatis
Himantura
Pastinachus
Pteroplatytrygon
Taeniura
Urogymnus Template:Taxobox end Stingrays are rays in the family Dasyatidae. They are cartilaginous marine fish. (The term "stingray" can also used be to mean any ray or skate in the order Rajiformes, but this article covers dasyatid stingrays only.)

Well-known species include:

• Southern Stingray, Dasyatis americana
• Atlantic Stingray, Dasyatis sabina
• Yellow Stingray, Urolophus jamaiensis
• Blue Spot Stingray, Taeniura lymma
• Pelagic Stingray, Pteroplatytrygon violacea
• Banded Stingray

Stingrays are common in tropical coastal waters throughout the world, and there are freshwater stringrays in South America (Potamotrygon sp.), Asia (Himantura sp.), Africa, and Florida (Dasyatis sabina). Most species of stingray are neither threatened nor endangered.

Rays swim with a "flying" motion, propelled by motion of their large pectoral fins (commonly referred to as "wings"). Their stinger is a razor-sharp, barbed or serrated cartilage which grows from the ray's whip-like tail (like a fingernail). It is coated with a toxic venom.

Stingrays do not "attack" aggressively, or even actively defend themselves. When threatened their primary reaction is to swim away. However, when they are attacked by predators or stepped on, the barbed stinger in their tail is mechanically whipped up, usually into the offending foot; it is also possible, although less likely, to be stung "accidentally" by brushing against the stinger. Contact with the stinger causes local trauma (from the cut itself), pain and swelling from the venom, and possible infection from parts of the stinger left in the wound, as well as from seawater entering the wound. It is possible for ray stings to be fatal if they sever major arteries, are in the chest or pelvic region, or are improperly treated. Their stingers are normally ineffective against their main predator, sharks.

Treatment for stings includes hot water (as hot as the victim can stand), which helps ease pain and break down the venom, and antibiotics. Vinegar or urine may or may not be successful in easing pain; neither cleans the wound properly. Other possible pain remedies include papain (papaya extract, contained in unseasoned powdered meat tenderizer), which may break down the protein of the toxins, though this may be more appropriate for jellyfish and similar stings. Pain normally lasts up to 48 hours but is most severe in the first 30-60 minutes and may be accompanied by nausea, fatigue, headaches, chills, etc.

Like other rays, stingrays are viviparous (bearing live young in "litters" of 5-10). Since their eyes are on top of their head, and their mouths on the bottom, they cannot see their prey, and instead use their sense of smell and electro-receptors similar to those of the shark. They feed primarily on mollusks and crustaceans, or occasionally on smaller fish; rays settle on the bottom while feeding, sometimes leaving only the eyes and tail visible.

Rays may be caught on a fishing line, using small crabs as bait, and are often caught accidentally; they may also be speared from above. They are edible but not normally preferred; small rays may be cooked similarly to other fish, typically grilled or battered and fried. While not valuable themselves, stingrays can damage shellfishing grounds.

Viewing stingrays

Stingrays are not normally visible to swimmers, but divers and snorkelers may find them in shallow sandy waters, more so when the water is unseasonably warm.

The Baltimore Aquarium has a large stingray tank where they may be viewed from above or below; many other aquariums exhibit rays.

In the Cayman Islands, there are a couple of dive sites (each called "Stingray City") where divers and snorkelers can swim with large southern stingrays and feed them by hand.

See also

• Hexatrygonidae (sixgill stingrays)
• Plesiobatidae (deepwater stingrays)
• Potamotrygonidae (river stingrays)
• Torpediniformes (electric rays).

External links

• National Geographic photograph of a large freshwater stingray

References

• Froese, Rainer; Pauly, Daniel (eds.). "Family Dasyatidae". FishBase. August 2005 version.

• Rays