 The diamond stingray is most active at night , spending much of the day buried in sand with only its eyes protruding . When foraging for food , it may be solitary but more commonly forms groups numbering up to the hundreds . There is strong segregation by sex and age . This species feeds on crustaceans , molluscs , and other invertebrates , as well as small bony fishes ; its powerful jaws and <unk> @-@ like teeth allow it to crush hard @-@ shelled prey . It mainly targets burrowing organisms , but may also take prey exposed on the bottom . There is a record of a female 69 cm ( 27 in ) across , that had <unk> herself on at least 30 small crabs . In the Bahía Magdalena <unk> complex , Baja California Sur , its most important source of food are pea crabs , followed by the razor <unk> <unk> <unk> , and then polychaete worms . 
