When it comes to which animal packs the most heat below the belt, you'd be surprised with the results. From birds to barnacles, see which members of the animal kingdom are the biggest hit with the females!

"Sex Lives of Barnacles is Record-Breaking" "Barnacles have the largest penises, relative to body size, in the animal kingdom, and now some are going into the record books for yet another feat: They can capture sperm directly from water."

"Sea Slug Has Disposable Penis" "A sea slug's unusual mating behavior -- it discards its penis after copulation, grows a new one, and has sex the next day -- is reported in the latest issue of Biology Letters."

"Evolutionary Oddities: Duck Sex Organ, Lizard Tongue" "In two new studies that highlight the curiosities of nature, scientists report on distinctive organs of chameleons and male Argentine lake ducks that give them an edge in very different functions: feeding and mating."

"Really Weird Bird Anatomy" "The closer you look, the weirder Mother Nature appears. Some birds that look absolutely common on the outside have anatomical features that will surprise you."