The sixgill stingray, or Plesiobatis daviesi, and the deepwater stingray, or Hexatrygon bickelli, are the only species in their respective stingray families. The sixgill stingray is a member of the Hexatrygonidae family, while the deepwater stingray is in the Plesiobatidae family. As its name suggests, the sixgill stingray has six visible gills on its back. Sixgills are native to the western Pacific and live near South Africa's coastline. Deepwater stingrays are known to live at depths of more than 2,200 feet along the coastlines of Australia and eastern Asia.
Some stingrays must live in freshwater -- primarily river inlets -- to survive. Primarily river stingrays, or Potamotrygonidae, and some species of whiptail stingrays, or Dasyatidae, in North America, South America and Africa, live in freshwater environments. River stingrays have a circular shape and grow up to 10 inches in diameter. The world's largest freshwater fish, the giant freshwater stingray, or Himantura chaophraya, is a whiptail stingray native to Southeast Asia. Giant freshwater stingrays grow up to 13 feet long.
Urotrygonidae is a family of stingrays that lives near the coastlines of North America and South America. They are more commonly known as American round stingrays, or round rays, because of their circular bodies. Round rays also have slender tails and no dorsal fins. Round ray species, or Urolophidae, include the spotted round ray, yellow stingray and stingarees. Unlike Urotrygonidae stingrays, stingarees are native to Australian and the South Pacific. Striped and shovelnose stingarees are other common Urolophidae stingrays.
All butterfly rays belong to the Gymnuridae family. They have flattened, butterfly-shaped bodies. Other physical characteristics are a short tail and pectoral fins. Butterfly rays live in the tropical waters of Asia, North America, Africa, southern Europe and South America. Typical Gymnuridae stingrays include the California butterfly ray, spiny butterfly ray and Japanese butterfly ray.
The Myliobatidae family represent all eagle rays, or stingrays with bird-shaped bodies and long tails. Eagle rays also can jump out of the water. They usually swim in open water, rather than on the ocean floor as most stingray species do. Spotted and banded eagle rays are two common Myliobatidae species. Eagle rays are primarily found in North and South America.