Stingray

The stingrays are a large suborder of the rays. They are cartilaginous fish related to sharks. They are in the suborder Myliobatoidei of the order Myliobatiformes, which consists of nine families.

Most stingrays have one or more barbed stings on the tail, which is used only for self-defence. The sting may reach about 35 cm, and its underside has two grooves with venom glands. The sting is covered with a thin layer of skin, the sheath, in which the venom is held. A few members of the suborder, such as the manta rays and the porcupine ray, do not have stings.Froese, Rainer, and Daniel Pauly, eds. 2009. "Mylobatoidei" in FishBase. FishBase online

Stingrays are common in coastal tropical and subtropical marine waters throughout the world. There are species in warm temperate oceans, and some found in the ocean. Some live in fresh water. Most stingrays live at or near the bottom of the water, but some are pelagic.

 Lifestyle 
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.

The flattened bodies of stingrays allow them to hide themselves. Stingrays agitate the sand and hide beneath it. Their eyes are on top of their bodies and their mouths on the undersides. Stingrays  use smell and electro-receptors (like those of sharks) to find their prey.

Stingrays feed mostly on molluscs, crustaceans, and occasionally on small fish. Some stingrays' mouths have two powerful, shell-crushing plates, while other species have sucking mouthparts that bring in the plankton.

 Reproduction 
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'.

At the Sea Life London Aquarium two female stingrays have delivered seven baby stingrays, although the mothers have not been near a male for two years. "Rays have been known to store sperm and not give birth until they decide the timing is right".

Like all fish, stingrays get little  parasites (such as flukes or copepods) on their gills or body. A cleaner fish helps the stingrays by eating the parasites it can get at.

 Families 
There are eight families in the stingray group. They are:
Hexatrygonidae (sixgill stingray),
Plesiobatidae (deep water stingray),
Urolophidae (stingarees),
Urotrygonidae (round rays),
Dasyatidae (whiptail stingrays),
Potamotrygonidae (river stingrays),
Gymnuridae (butterfly rays), and
Myliobatidae (eagle rays).Nelson J.S. 2006. Fishes of the World. 4th ed, Wiley.

 References 

Category:Rays
Category:Venomous animals