In this large and diverse world of ours', there are infinite ways for human bodies to be (check out Mutants: On Genetic Variety and the Human Body for some excellent reading on the topic); but when we branch out beyond our own species, and even our own mammalia class, the variation is almost beyond our comprehension: my favorite invertebrate, the octopus, possesses a dazzling level of intelligence despite its brief life span, male seahorses become pregnant and birth the young, and birds, amphibians, reptiles, monotremes, and marsupials possess a cloaca.The cloaca is a posterior orifice (or vent) that serves as a release for the intestinal, urinary, and (usually) genital tracts. Charmingly enough, the term for avian mating is also known as the "cloacal kiss"; even more charming still is the recent discovery that some species of male wrens may have a built-in vibrator solely for their mate's pleasure.From newscientist.com:

SOME male birds possess a wiggling tongue-like knob on their genitals, probably to titillate their mates.In typical bird copulation, males and females momentarily press together their cloacas - genital openings - in what biologists call a cloacal kiss. A muscled tongue-like projection called a cloacal tip, spotted for the first time in males of several species of Australian wrens, means this might be more like a French kiss.Melissah Rowe of the University of Chicago and colleagues studied eight species of wrens. Based on the alignment of the muscles, the cloacal tips seem able to wiggle from side to side. Though Rowe hasn't seen a tip in action, she says it would be odd to find a structure made of muscle that didn't move (Journal of Avian Biology, DOI: 10.1111/j.2008.0908-8857.04305.x).The team also found that the tips were proportionally larger in wren species where females mate with many partners, suggesting that its function might be to stimulate females and encourage them to take up and retain the males' sperm, says Rowe.

Whether you see it as intelligent design or a built-in sex toy, I'd like a moment of praise for the biological diversity to be found amongst our fine feathered friends.*Thank you to my dear friend, Jessica Promdress, for sharing this article with me.