 When searching for food , diamond stingrays may form groups of up to hundreds of individuals . It is most active at night and <unk> mainly on burrowing invertebrates and small bony fishes , which are extracted from the bottom via <unk> or digging . This species is aplacental viviparous : once the embryos exhaust their yolk supply , they are nourished by histotroph ( " uterine milk " ) produced by the mother . Females bear 1 – 4 <unk> every summer in estuaries ; mating is followed by a ten @-@ month period of either sperm storage or arrested embryonic development , after which the embryos rapidly mature over 2 – 3 months . The slowest @-@ growing stingray known , this species is not <unk> against fishing pressure . It is caught for food by <unk> fishers in Latin America , particularly in Mexico where it is one of the most economically important rays . This has led it to be assessed as Near Threatened in Mexico by the International Union for Conservation of Nature ( IUCN ) , while the species as a whole is listed as Data <unk> . Though <unk> towards humans , the diamond stingray 's long , venomous tail spine is potentially dangerous . 
