How hedgehop do it, and other bits of carnal knowledge. Sparks, kind of a seminal thinker, quickly slides past screwworms and lovebirds who, their names notwithstanding, are rather unexceptional sexually and alights on more diverting phenomena: the blue whale, possessor of the world's largest penis; rodents, whose copulatory speed is pace-setting; the boar, record-breaking ejaculator; and similar Guinness contenders. Snails proceed at a snail's pace, male spiders often serve as honeymoon breakfasts, and blood flukes, at first sight, link up for ""permanent rapture."" Also, Australian quoth perform double-decker sex, surgeon fish go in for group sex, and foam frogs engage in what looks like an erotic cooking session so that everybody can simultaneously. Tongue in cheek, or wherever, zoologist Sparks pokes around among all these private parts, and except for a few dispensable homosexual asides and an early climax, it's as smooth as. . . well, it instructs as it self-lubricates.