Australia is home to over 140 species of marsupials - the three newest of which are antechinuses. These are slightly larger than mice and have dense brown fur, except for a patch of white on the belly.
While attempting to create a field guide for hikers and naturalists, scientists discovered three previously unknown species of antechinus. This announcement brings the total number of antechinus species to 13. Though the total population of these species is unknown, some speculate that they may eventually be listed as threatened or endangered, due to natural predators and destruction of habitat.
It has been claimed that there are two more new antechinuses, though it has not been confirmed that they truly represent new species. However, there are large areas of land out in the bush that haven’t been thoroughly cataloged so it’s possible that there are several more still out there.
Antechinus males are known for their intense sex lives. By the time mating season begins, the male antechinus has already stopped making sperm and only seeks to empty the stockpiles. This comes in a wild frenzy, trying to quite literally mate as much as physically possible. He ignores food and sleep, and seeks only to mate. As the days progress, testosterone and stress hormone levels are at an all time high, fur begins to fall out, internal bleeding sets in, and the immune system fails, allowing gangrene, parasites, and liver failure to take over. Even after he is completely disheveled, he still seeks another mate up until his dying breath.
The mating season is 2-3 weeks long and culminates in the death of every antechinus male. Toward the end of this marathon of mating, the females show a decreased interest in the males. This could be because they have already conceived and just aren’t receptive to mating anymore, or it could be because the males look completely disgusting.
This past August, a paper was published in the Proceedings of the National Academy of Sciences which helps to explain why these males would have a “doesn’t matter, had sex” attitude toward dying this way. Reproduction determines evolutionary winners and losers, which is why mating is such serious business. Sperm competition is so high among antechinuses that taking a break for sleeping, eating, or grooming just takes time away from looking for a lady and diminishes the chance of getting to sire offspring. This method of “one and done” reproduction is known as semelparity.
Update (11/4/13): Edited to remove incorrect information about food competition.