The rat-sized antechinus rose to infamy last year when it was revealed that males of the species literally killed themselves through overly vigorous sex sessions. Living no longer than a year, they would spend the mating season frantically pursuing any and all opportunities for copulation, with some encounters lasting up to 14 hours. This insatiable appetite for procreation eventually burns their little bodies out and they perish, making room for the next generation of oversexed marsupials.

Redefining the idea of an insatiable appetite

While such suicidal sex practices are relatively common among insects — the praying mantis female can bite the male's head off during sex, which actually improves the chances of procreation as the remnant body continues working — the antechinus is relatively unique among mammals. Now, Australian scientists have discovered three new species, with the very latest being the black-tailed antechinus found in the Gondwana Rainforests. It hasn't yet been confirmed to engage in the same reproductive practices as its cousin, but Dr. Andrew Baker of the Queensland University of Technology says that it's "highly, highly likely."

Various theories have been advanced for why the antechinus engages in its annual ritual of self-destruction. The most probable one so far appears to be that the males are competing not by fighting or dominating a group, but simply by who can inseminate the most females. It's the pursuit of this goal, even beyond the brink of exhaustion, that drives to keep copulating.