The plain maskray or brown stingray ( Neotrygon annotata ) is a species of stingray in the family Dasyatidae . It is found in shallow , soft @-@ bottomed habitats off northern Australia . Reaching 24 cm ( 9 @.@ 4 in ) in width , this species have a diamond @-@ shaped , grayish green pectoral fin disc . Its short , whip @-@ like tail have alternating black and white bands and fin folds above and below . There are short rows of thorns on the back and the base of the tail , but otherwise the skin is smooth . While this species possess the dark mask @-@ like pattern across its eyes common to its genus , it is not ornately patterned like other maskrays .