Fossil range: Late Cretaceous–Recent
|Southern stingray, Dasyatis americana|
The stingrays are a family—Dasyatidae—of rays, cartilaginous fishes related to sharks. They are common in coastal tropical and subtropical marine waters throughout the world, but the family also includes species found in warmer temperate oceans such as Dasyatis thetidis, and species entirely restricted to fresh water such as D. laosensis and Himantura chaophraya. With the exception of Pteroplatytrygon violacea, all dasyatids are demersal.
They are named after the barbed stinger (actually a modified dermal denticle) on their tail, which is used exclusively in self-defense. The stinger may reach a length of approximately 35 cm, and its underside has two grooves with venom glands. The stinger is covered with a thin layer of skin, the integumentary sheath, in which the venom is concentrated. Some species have several stingers, and a few, notably Urogymnus asperrimus, lack a sting entirely.
Other types of rays also referred to as stingrays are the river stingrays (family Potamotrygonidae), the round stingrays (families Urolophidae and Urotrygonidae), the sixgill stingray (family Hexatrygonidae), and the deepwater stingray (family Plesiobatidae). For clarity, the members of the family Dasyatidae are sometimes called whip-tail stingrays.
While most dasyatids are relatively widespread and not currently threatened, there are several species (for example Taeniura meyeni, D. colarensis, D. garouaensis, and D. laosensis) where the conservation status is more problematic, leading to them being listed as vulnerable or endangered by IUCN. The status of several other species are poorly known, leading to them being listed as Data Deficient.
The flattened bodies of stingrays allow them to effectively conceal themselves in their environment. Stingrays do this by agitating the sand and hiding beneath it. Because their eyes are on top of their bodies and their mouths on the undersides, stingrays cannot see their prey; instead, they use smell and electro-receptors (ampullae of Lorenzini) similar to those of sharks. Stingrays feed primarily on molluscs, crustaceans, and occasionally on small fish. Some stingrays' mouths contain two powerful, shell-crushing plates, while other species only have sucking mouthparts. Stingrays settle on the bottom while feeding, often leaving only their eyes and tail visible. Coral reefs are favorite feeding grounds and are usually shared with sharks during high tide.
When a male is courting a female, he will follow her closely, biting at her pectoral disc.
Stingrays are ovoviviparous, bearing live young in "litters" of five to thirteen. The female holds the embryos in the womb without a placenta. Instead, the embryos absorb nutrients from a yolk sac, and after the sac is depleted, the mother provides uterine "milk".
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. Stamping hard on the bottom as one treads through murky water will also cause them to swim away. Humans who harass or appear to harass stingrays have been known to be stung elsewhere, sometimes leading to fatalities. 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 (0.49 to 0.79 in) per month (though with significant variations depending on the size of the stingray and the exact species). Contact with the stinger causes local trauma (from the cut itself), pain, swelling, and muscle cramps from the venom, and possible later infection from bacteria. Immediate injuries to humans include, but are not limited to: poisoning, punctures, severed arteries, and sometimes death. Fatal stings are very rare, but can happen, famously including Steve Irwin.
Treatment for stings may include application of hot water (optimum temperature is 45 °C (113 °F), taking care not to cause thermal burns), which can help ease pain by denaturing the complex venom protein, and antibiotics. 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, 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; but x-ray radiography imaging may be helpful where ultrasound is not available.
Rays are edible, and may also be caught as food by fishing lines or spears. Stingray recipes abound throughout the world, with dried forms of the wings being most common. For example, in Singapore and Malaysia, stingray is commonly barbecued over charcoal, then served with spicy sambal sauce. Generally, the most prized parts of the stingray are the wings, the "cheek" (the area surrounding the eyes), and the liver. The rest of the ray is considered too rubbery to have any culinary uses.
While not independently valuable as a food source, the stingray's capacity to damage shell fishing grounds can lead to bounties being placed on their removal.
After Steve Irwin's death by a stingray, fishing for stingrays greatly increased, apparently as revenge for the famed zoologist's death.
Stingrays are usually very docile and curious, their usual reaction being to flee any disturbance, but will sometimes brush their fins past any new object they come across. Nevertheless, certain larger species may be more aggressive and should only be approached with caution by humans, as the stingray's defensive reflex may result in serious injury or death.
Dasyatids are not normally visible to swimmers, but divers and snorkelers may find them in shallow sandy waters, more so when the water is warm. In the Cayman Islands there are several dive sites called Stingray City, Grand Cayman, where divers and snorkelers can swim with large southern stingrays (D. americana) and watch while professional scuba instructors feed them by hand. There is also a "Stingray City" in the sea surrounding the Caribbean island of Antigua. It consists of a large, shallow reserve where the rays live, and snorkeling is possible.
In Belize off the island of Ambergris Caye there is a popular marine sanctuary called Hol Chan. Here, divers and snorkelers often gather to watch stingrays and nurse sharks that are drawn to the area by tour operators who feed the animals.
Many Tahitian island resorts regularly offer guests the chance to "feed the stingrays and sharks". This consists of taking a boat to the outer lagoon reefs then standing in waist-high water while habituated stingrays swarm around, pressing right up against tourists seeking food from their hands or that being tossed into the water. The boat owners also "call in" sharks which, when they arrive from the ocean, swoop through the shallow water above the reef and snatch food offered to them.
The skin of the ray (same) is used as an under layer for the cord or leather wrap (ito) on Japanese swords (katanas) due to its hard, rough, texture that keeps the braided wrap from sliding on the handle during use. They are also used to make exotic shoes. They are used to make boots, belts, wallets, jackets, and even cellphone cases.
Henry de Monfreid states in his books that before World War II, in the Horn of Africa, whips were made from the tail of big stingrays, and that this device inflicted cruel cuts, so in Aden the British forbid its use on women and slaves. In former Spanish colonies a stingray is called raya làtigo ("whip ray").
Monfreid also writes in several places about men of his crew suffering stingray wounds while stranding and wading into Red Sea shallows to load or unload smuggled wares: he wrote that to "save the man's life" searing the wound with a red-hot iron was necessary.
Although stingray teeth are nowhere near as common on sea bottoms as shark teeth, scuba divers searching for the latter often encounter the teeth of stingrays. Permineralized stingray teeth have been found in sedimentary deposits around the world, including fossiliferous outcrops in Morocco.
|Southern stingray, Dasyatis americana|
[[File:|thumb|Blue Spotted Ray]] Stingrays are a form of sea creature. There are 70 kinds of stingrays in the world. Most types of stingrays live in saltwater (sea), close to land, in warm parts of the world. A small number live in freshwater (lakes and rivers).
Stingrays are a part of the Ray family of fishes. Most rays are stingrays, and stingrays are (like eagle rays and electric rays) true rays. They are flat and push themselves through water by moving their bodies up and down in a wave motion. Rays are something like flattened sharks. They, like sharks, have something called cartilage instead of bone. Cartilage is what the tip of your nose is made from.
Some stingrays are smaller than your hand and some are as big as an adult man.
Stingrays have a tail with Stingers - sharp points that are covered in poison. A stingray cut causes pain for humans but death is very rare. The stinger on the tail of the stingray can be up to 8 inches long. Stingrays like to eat meat such as clams and shrimp that live on the ocean floor. Their eyes are on top of its body so they cannot see their food. They use special electrical messages from animals and what they smell to find food. Then they use their strong teeth to smash the shells of the animals to get to the meat inside.
Most fish lay eggs in the water, but stingrays do not. They give birth to baby stingrays. Female stingrays give birth once a year to two to ten babies. Baby stingrays, called pups, are born after two to four months. They are born with sharp spines in their tails. The sharp spines help them stay safe.
Stingrays sometimes get little animals stuck on them and this can make them sick. A little fish helps the stingrays by eating the little animals that get stuck on them for its supper.
Stingrays do not have homes; their body can keep them safe and comfortable on the ocean floor. Their flat bodies let them hide in sand or mud. Most stingrays are greenish or brownish so they can hide in sand or mud. Stingrays that live in coral reefs with nice colors have nice colors too.
Stingrays have to stay safe mostly from sharks that like to eat them. Their sharp tail can keep them safe from many animals. If a stingray is stepped on, its sharp tail can really hurt. Stingrays do not usually hurt other animals. When they are scared they usually swim away.
In the world of the baseball, they are the former name of the Tampa Bay Rays. From the team's start in 1998 up until November 2007 the team was known as the Tampa Bay Devil Rays, when the team changed name they also changed their uniforms. On the new uniforms on one of the sleeves is a sting ray symbol, keeping some heritage to the old name. Also, in left field of the Rays' stadium (Tropicana Field) is a fish tank containing some Cownose rays. The tank is looked after by the Florida Aquarium. The male stingray is always on top.