The platypus is a bit like a fruitcake. Shove a bunch of leftover genes in there, mix it up and send it to your relatives see what kind of animal you get.
That’s kind of the approach evolution used when designing this odd creature’s venom; scientists have just determined that the venom contains over 80 different toxins in 13 different classes. The poison can kill small animals, and can leave humans in pain for weeks. The venom is delivered through a barb on the male’s foot–it’s thought that the fellas use the poison during mating season to show dominance.
At least three of the toxins are unique to the platypus and the rest are strikingly similar to proteins from a variety of animals including snakes, lizards, starfish, and sea anemones. It seems that some of these toxins have evolved separately in different animal lineages to perform the same function, a process called convergent evolution. The study‘s lead author, Wesley Warren, told Nature News:
Warren says that this probably happens when genes that perform normal chores, such as blood coagulation, become duplicated independently in different lineages, where they evolve the capacity to carry out other jobs. Animals end up using the same genes as building blocks for venom because only a subset of the proteins the genes encode have the structural and functional properties to become venoms, he adds.