Stingrays are a group of fish that belong to the family Dasyatidae, which includes over 140 species. They are found in shallow, warm waters worldwide, including the Atlantic, Pacific, and Indian Oceans. Stingrays are closely related to sharks and are characterized by their flattened bodies, long tails, and venomous stinging spines.

The earliest known stingrays lived around 55 million years ago in the early Eocene period. They were relatively small and primitive compared to modern stingrays. Still, they already showed many characteristics associated with stingrays today, such as their flattened bodies and long tails.

Stingrays are known for their distinctive diamond-shaped bodies and ability to move through the water by undulating their pectoral fins. They are also known for their highly sensitive skin, which is covered with tiny, tooth-like structures called dermal denticles. These denticles help to protect the stingray's skin from damage and also help to reduce drag as the stingray moves through the water.

One interesting fact about stingrays is that they are often mistaken for sharks due to their similar body shape and the fact that they are often found in the same habitats. However, stingrays are quite different from sharks and are much more docile and less aggressive. In fact, many species of stingrays are completely harmless to humans and pose no threat at all.

Another interesting fact about stingrays is that they are a popular food source in some parts of the world. In some cultures, stingray meat is considered a delicacy and is often grilled, fried, or smoked before being eaten. However, due to overfishing and habitat destruction, many species of stingrays are now considered endangered and are protected by international conservation laws.