Venomous?

Protection:
Each foot on the platypus contains five digits, each consisting of a broad nail for the forefeet and sharp claws for the hind feet. They also have webbed feet and a large flat tail perfect for swimming away from other predators.

Spurs:
The male Platypus has a sharp, hollow, horny spur about 15 millimeters long on the inside of both hind leg ankles. This is connected to a venom gland which produces a very strong toxin. The spur can be used in defense against predators but the fact that it is restricted to the male - and that the gland reaches its greatest development in the mating season, suggests that it is normally employed in aggressive encounters between males. The spur is located on the back legs because of predators chasing them from behind. They are the fifth most venomous mammal in the world!

Male Spurs and Venom Glad