Only males possess the toxin. Females pose no threat because their spurs disappear before the first year of life. The venom is not lethal to humans, but the sting causes severe pain, making normal functioning impossible. After a sting, swelling appears around the wound, spreading to the entire limb. Venom production increases during the reproductive period of platypus and it is believed that males use the toxin to assert their dominance rather than to kill the intruder.
