[3] The spiny-tailed monitor is distinguished from the similar-looking species V. baritji and V. primordius by the presence of pale longitudinal stripes on the neck.

[2][3] V. a. acanthurus is native to northern Australia, from Broome on the west coast, through the Kimberley and the Top End, to the Gulf of Carpentaria.

V. a. brachyurus can be found in the center, western, and eastern parts of the ackie's total range, as far west as Carnarvon and as far east as Mt.

[10] In 2006, the results of a study on the mtDNA of Australian monitors were published, according to which the two continental subspecies do not form natural (monophyletic) taxonomic entities.

[9] Wilson and Swan (2010) still accept V. a. insulanicus as a valid subspecies of V. acanthurus, which is easily distinguished from other spiny-tailed monitors by its dark colouration and more banded pattern.

[3] Sheltering underground gives them access to humid microclimates which helps keep them hydrated enough to survive the otherwise arid nature of their habitat.

[12] They prey mainly on arthropods, such as grasshoppers, beetles, cockroaches, spiders, isopods, caterpillars, cicadas, snails, stick insects, centipedes, crickets, and ticks.

[12][17] There are a number of methods of sexing ackie monitors, although the hemipenal transillumination technique[18] is generally considered to be the easiest and most accurate.

Male ackie monitors are generally larger, have blockier heads, and have grippy scales on the underside of their tail.