A round marbled disc lying buried in sand with two eyes on top, no barb on the tail, and a pair of organs behind the eyes that can deliver a shock of around 200 volts.
The organs are modified muscle. Thousands of flattened cells are stacked like the cells of a battery, each contributing a fraction of a volt, and the whole column fires at once when a nerve signal arrives. The ray uses it twice over: a heavy discharge to stun prey, which it then wraps in its disc and moves to its mouth, and a lighter one as defense.
A shock is not dangerous to a healthy adult, but it is entirely capable of knocking someone off their feet in shallow water, which is where the danger lies. The animal is buried, invisible, and does not move away - injuries are from standing on one.
This is also the fish that gave medicine its first electrical device. Roman physicians treated headache and gout by having patients stand on a live torpedo ray, and the effect was real enough that the practice ran for centuries. The word torpedo, for the numbness it produces, is older than the weapon.
- round flat disc, marbled brown on cream, with a short thick tail
- two dorsal fins and a paddle-shaped tail fin, unlike a stingray
- no tail spine at all
- usually buried, with only the eyes and spiracles showing
- width up to 60 cm, length up to 100 cm
