Joseph Castro

Even plants and animals like to leave a good impression.

The complicated world of hyena sex involves social hierarchies, weird and potentially dangerous courtship rituals and female pseudopenises that make forced sex impossible.

When it comes to sex, are butterflies as nurturing and gentle as they appear to be, or is there a more aggressive side to their mating?

Antechinus sex involves ambushes, intermittent copulation lasting 14 hours and ultimately suicide.

Rather than mundane, lazy sex, sloths participate in quite the mating game. In fact, sloth sex involves high-pitched screams, promiscuity and eye-gouging battles.

Polar bear sex involves long-distance tracking, fierce battles and lengthy copulation.

Octopus mating involves shifting body colors, detachable "penises," long-distance mating and sexual cannibalism.

Fractures on spear points show, for the first time, that the first North Americans really did use spear-throwers to hunt from safe distances.

Anglerfish mating involves biting, tissue fusion and the complete lack of mate choice by females.

Dung beetle sex involves short breeding periods, intense competition and, of course, poo.

Flaming sex involves make-up, elaborate group dances and seasonal monogamy.

Snake sex involves mating balls, battles similar to arm-wrestling and, sometimes, asexual reproduction.

Long thought to show a random assortment of animals, an ancient two-handled wine cup may actually show one of the earliest depictions of Greek constellations.

Not unlike humans, male tree frogs call on females to begin the mating game, and females prefer long calls.