There are about 500 different species of rays, inhabiting our oceans and rivers. They are close cousins of sharks and, like them, seem to have appeared over 150 million years ago.
Like sharks, skates and rays have no bones or bones. Instead, their skeleton is made of cartilage (like your nose or ears). This makes them particularly light and improves their aquadynamics. That's why they seem to "fly" gracefully in the water.
Stingrays have a poisonous sting at the base of their tail. When they feel threatened, the stingrays wave their tail towards the attacker to sting him/her. Sometimes they leave the thorn behind. This is why even though a new stinger will eventually reform, they only sting as a last resort.
You can discover several species of stingrays at the aquarium: the blue-spotted stingray and the Atlantic stingray in the tropical area and Amazonian stingrays in the exhibition of the same name.