 Adult rays have a wide band of flattened , heart @-@ shaped dermal denticles that extend from between the eyes to the tail spine , increasing in density with age , along with two large pearl thorns at the center of the back . The tail behind the spine is covered by small thorns . The dorsal band of denticles is largely developed by the time the juveniles are 50 cm ( 20 in ) across . The coloration of the reticulate whipray varies substantially with age and locality . Adults generally have a dorsal pattern of numerous closely spaced dark brown spots or reticulations on a beige to yellow @-@ brown background , which becomes blackish past the spine with lighter bands on the sides . The underside is pale , without markings . Juveniles are yellowish above with tiny , densely packed dark spots , around seven spots in a line between the spiracles , and three rows of spots in front of the sting . This large species has been reported to reach a disc width of 2 m ( 6 @.@ 6 ft ) , a total length of 6 m ( 20 ft ) , and a weight of 120 kg ( 260 lb ) . 
