Platypus fact of the day: venom

The platypus is one of only a handful of truly venomous mammals. Both males and females start life with little 'spurs' just above each hind leg, but the females don't produce venom and the spurs basically fall off within the first year of life. The male produces venom, and can articulate the spur to a 90-degree angle to attack.

The venom isn't powerful enough to kill most animals, though it is apparently extremely painful to humans. Because of this it's not likely used strictly as a defensive mechanism, and the fact that venom production increases around mating season indicates that it may just be used to fight other males for dominance.

And of course, we're not entirely certain how their venom works; many venoms cause tissue to die, whereas the platypus skips that.