"Inside Nature's Giants" on PBS "Inside Nature's Giants," besides being the liveliest scientists-at-work program to come along in a while, is the perfect thing for anyone trying to lose weight. You won't be doing any snacking while watching this cut-them-open extravaganza. Windfall Films Mark Evans and Joy Reidenberg with a beached sperm whale, the subject of the first episode of "Inside Nature's Giants." The four-part series, which begins on Wednesday night on PBS, features a team of experts who dissect a different large animal each episode. The animals all died naturally or were killed in sanctioned culls. This week it's a sperm whale that died after beaching itself in Britain. It's not often you'll see researchers using construction equipment and a chain saw to study their subject. That's what's needed to get into the carcass, but get in there we must because, the narration tells us, "The guts of whales are windows into dark and hidden worlds." Sure enough, they are: a whale feeds by deep-diving into parts of the ocean humans know little about, so what's in its stomach - three stomachs, actually - can be informative. The team is well selected. It consists of Mark Evans, a veterinary scientist; Joy Reidenberg, a comparative anatomist; Simon Watt, a biologist; and the evolutionary biologist Richard Dawkins, who sheds light on how the beast of the week fits into the grand scheme of things. The four approach their work with verve and humor. "It's like walking down the butcher's aisle in the supermarket," Ms. Reidenberg says as she cuts into the whale. All the meat's really fresh here. Just then a cut she makes releases some gas trapped inside the animal, giving her an unpleasant blast in the face. "Probably poked one of the intestines," she explains. Viewers who can handle the rather blunt footage of the dissections can learn quite a lot. The scientists explain the evolutionary adaptations that enable sperm whales to dive to potentially crushing depths, along with other interesting tidbits. "Sperm whales can suckle for up to 13 years," the narration relates. Once they reach the stomachs, they also gain insight into why this particular animal died. They're doing all this while racing against an incoming tide. Subsequent episodes look at giant pythons, a great white shark, and a lion and a tiger. Gruesome, certainly, but illuminating.