Washington, Jan 15 : Duck-billed platypus, a semi aquatic mammal, is a soft and cuddly creature, but can also knock you senseless if you venture too close.

The males can deliver a mega-sting that causes immediate, excruciating pain, like hundreds of hornet stings, leaving victims incapacitated for weeks.

Now scientists are a step closer to deciphering the venom's chemical composition, with the first identification of a dozen protein building blocks.

Masaki Kita of the University of Tsukuba, Japan, Daisuke Uemura and colleagues note that spurs in the hind limb of the male platypus can deliver the venom, a cocktail of substances that cause excruciating pain.

Scientists previously showed that the venom triggers certain chemical changes in cultured human nerve cells that can lead to the sensation of pain. Until now, however, scientists did not know the exact components of the venom responsible for this effect.

To unlock its secrets, the scientists collected samples of platypus venom and used high-tech analytical instruments to separate and characterise its components, said an American Chemical Society (ACS) release.

They identified 11 new peptides, or protein subunits, in the venom. Studies using nerve cells suggest that one of these substances, called Heptapeptide 1, is the main agent responsible for triggering pain. The substance appears to work by interacting with certain receptors in the nerve cells, they suggest.

Their study was published in the Journal of the American Chemical Society. (IANS)