 The diamond stingray <unk> a disc width of 1 m ( 3 @.@ 3 ft ) or possibly 1 @.@ 2 m ( 3 @.@ 9 ft ) ; females grow larger than males . Its pectoral fin disc is <unk> in shape , slightly wider than long , with angular outer corners and subtly convex margins . The snout is blunt @-@ angled and non @-@ projecting . The eyes are fairly large and immediately followed by the spiracles ( paired respiratory openings ) . The mouth is strongly curved , containing 21 – 37 upper tooth rows and 23 – 44 lower tooth rows ; the teeth are small and blunt , and arranged into flattened surfaces . Three or five papillae ( <unk> @-@ like structures ) are found in a row across the floor of the mouth . 
