Some of our great fascinations with the 1.75 million species of the natural world include the following questions: are they male or female, how big do they get, where do they live, how do they reproduce and what do they eat? Some of those questions are easier to answer than others. Most require careful study and other cases are opportunistic. For example how do you figure out what a sperm whale eats (scientists know them as Physeter macrocephalus)? There are some clues from stories of the most famous whale, Moby Dick, but more scientific endeavors involve careful study. The best way to understand what a sperm whale prefers to eat is to watch it feed, but that has never happened. The next best thing is to look at gut contents, the accumulation of debris left after eating. When a sperm whale dies and is discovered by a scientist, it is an opportunity that causes a flurry of investigation, including an exploration of the gut contents. From time to time the Canadian Museum of Nature receives these piles of bones. Our experts study each bone carefully using our extensive osteology collection (prepared skeletons for many of the 1200 marine fish species and the other vertebrates from Canada). Scientists know that their favorite meal is squid, and the gut contents also contain fish remains, including members of the cod family; eaten by the squid or by the whale. Because no one has ever seen a sperm whale feeding even the most basic information about these marine giants is still uncertain, indirect and mysterious. These investigations inform science about feeding relationships between species, helps us understand how sperms whales make a living and how our quest for food might affect them.