The whiptail stingrays are a family, the Dasyatidae, of rays in the order Myliobatiformes. They are found worldwide in tropical to temperate marine waters, and a number of species have also penetrated into fresh water in Africa, Asia, and Australia. Members of this family have flattened pectoral fin discs that range from oval to diamond-like in shape. Their common name comes from their whip-like tails, which are much longer than the disc and lack dorsal and caudal fins. All whiptail stingrays, except the porcupine ray (Urogymnus asperrimus), have one or more venomous stings near the base of the tail, which is used in defense. In order to sting their victims, they jerk their tails as the stinger falls off and stays in the wound that they have created. The stinger of a whiptail stingray is pointy, sharp with jagged edges. During mating season, males often hold onto females by using teeth which curve towards the corners of their mouths. They range in size from 0.18 to 2.0 m (0.59 to 6.56 ft) or more across in the case of the smalleye stingray and giant freshwater stingray. Species, being highly electroreceptive, can detect weak electric fields from prey. Electroreception is a product of electroreceptors dispersed across the skin. This network of pores is part of organs known as the ampullae of Lorenzini.