Bitis arietans gets its English name from its unusual arithmetic dexterity and its sexual preferences. Although it is known as the Common Puff Adder, there are thankfully few in these parts, with the exception of one that is behind a thick pane of glass in the zoo. It is notoriously lazy and can spend days on end without doing a stroke of work. Its poikilothermic nature is thus probably the result of burrowing (and borrowing) and basking in preference to habitual employment in useful work.