Like their shark cousins, rays and skates have a cartilaginous skeleton instead of a bony skeleton like the majority of fish.
Stingrays are mainly marine creature.
A few freshwater species are found on other continents, but none inhabits North American lakes and rivers. Along the underside of a ray's spine are two grooves containing venom-secreting, glandular tissue. The spine is covered with a thin layer of skin called the integumentary sheath. Toxin is concentrated in the integumentary sheath. The most common sites of injury are the extremities-lower legs for waders, arms for fishermen.