The giant stingray is one of the world's largest freshwater fish, but it's also cloaked in mystery. No one is sure how many giant stingrays are left, which habitats they prefer, or even if they ever venture into the ocean, where their more commonly known relatives dwell.
These ancient fish, little changed over many millions of years, can reach 16.5 feet (5 meters) long and weigh up to 1,320 pounds (600 kilograms). They are brown to gray in color, wide and flat in form, and they sport a long, whiplike tail.
Giant stingrays are known to prowl river systems in Thailand, Borneo, New Guinea, and northern Australia. They often bury themselves in sandy or silted river bottoms and breathe through holes, or spiracles, located on top of their bodies. Stingrays locate prey, usually clams and crabs, with a sensor that can detect an animal's electrical field.
Stingray numbers appear to have dropped dramatically in recent years as their riverine habitats have degraded, and it appears they no longer inhabit some parts of their historical range. Large stingrays have been known to pull boats upstream and even underwater.
Though stingrays do not readily attack humans, they are one of the few megafishes that can pose a real danger to those who handle them. Each ray sports a deadly barb on the base of its tail that can easily penetrate human skin and even bone, much like a hunting arrow. This stinger can be as long as 15 inches (38 centimeters) and typically introduces toxins to the victim's wound.