Very Venomous Platypus

 The male platypus is one of the few venomous mammals.

 

Picture from Zoos Victoria

Both male and female platypuses are born with ankle spurs, but only the male's spurs produce venom.   While the venom is powerful enough to kill smaller animals such as dogs, it is not lethal to humans.  However, the pain can be so excruciating that the victim may be unable to move.