Unlike most stingrays, the order Rhinoptera is an actively swimming inhabitant of the water column. They have a broad body and a tail that exceeds it in length, the purpose of which has remained controversial. A new study of the East American stingray Rhinoptera bonasus has shown that its tail is a “hydrodynamic antenna.” It is located on a special mechanoreception organ – the lateral line – with the help of which the stingray senses the movement of water, fish and other objects around it.