Thembones

Forgetabout skeletons inthecloset—SanFrancisco’sCalifornia AcademyofSciences hasskeletons on its roof. That’s right:Thelivingroof,mostlycovered with2.5 acres ofhills andnative California plants,also is hometowhale bones,which are placed there for degreasingvia natural forces such as wind, rainand sunlight.Thisis just onemethod thatacademy researchers usetocleanand preparebonesbeforethey becomepartofscientificcollectionsorexhibits.Thisprocess also allows researchers tostudy a specimen’slifehistory,including itsdiet andage.Thelocationofthese bonesonthe roof canvary,but visitorsusually canseesome ofthe larger bones from the main roof observation deck. The jawbonesof a 49-foot sperm whale tookresidence on theroofafter the animal washedup inPacificainApril.Here’salookathow theacademy’s processworks:

The bones are transferred from the beach. Thetwo spermwhale jawbones, togetherweighing700 pounds, werecarried upthe beach inatarp by ateamof17.The mandibles thenrodeona truckupthehighway and inthe academy’sfreightelevatorbefore they were hauledup twoflightsofstairs(byhand!) totheroof.

The bones are buried under alargemoundofsoil tolet bacteria andbugs naturallycompost the muscle and gum.The museum’slandscapeteam thenplaces nativeplantson top.The decomposition processcleans thebonesandhelps theplants grow.Bonesgenerally are buriedfrom sixmonths to a year.

Once the tissue has completelydecomposed andthe bones are clean, they are excavated. Theacademyexcavates the bones carefully —just likeatanarchaeological dig site — so that the teetharenot lost. The processgenerallytakesseveral hours and ahandful of people, butit can vary, depending on thespecimen.

Researchersremove the teeth, cutthem inhalf and examine thelayers todeterminethewhale’sage.Theystudy tiny samples of dentin,acomponent oftheteeth,tounderstandtheanimal’s diet. Onceremoved, teetharestoredin the research collection, makingiteasierfor researcherstostudy them in furtherdetail.

The bones are left on the roof for degreasing and bleaching by the sun. Oilcan leach to thesurface ofbonesoveraperiod oftime. The naturalelements—the sun,wind and rain—that thebones areexposed to ontheroof are parts of the overall cleaning processand help movethe grease out ofthe bone.

The bones usually will jointhe academy’sscientific collection. The museum sometimes leavesboneson theroof for public display.The number of specimensondisplay on the roof varies,but at the time of thiswriting, theacademy had sixsets ofbones, including the spermwhale.