The hidden afterlife of a sperm whale skeleton
Back in April, a 48 foot-long sperm whale was found on a beach in Pacifica called Mori Point. A lot of people had gathered around the whale to bear witness to its death. They inspected the animal’s internal organs, nervously poked its cracked flesh when no one was looking, and took a few selfies in the process. Mostly though? People want to know how this animal died - and if we had anything to do with it.
At one point this spring, six whale carcasses - including this one -were discovered on Northern California beaches over the span of five weeks. More followed. These deaths have a lot of people asking what’s going on, and what happens to these whales once they wash up ashore. Many of the whales that were found dead were humpback whales and gray whales, making this sperm whale in Pacifica a little different.
Maureen “Moe" Flannery, the Collections Manager at the Department of Ornithology and Mammology at California Academy of Sciences, tells me that “it's uncommon for us to have deep water offshore animals on the coast. It's much more common to have gray whales or humpback whales.”
When a stranding is reported, Flannery and her team head to the site to perform a necropsy as soon as possible to try and get the freshest sample - usually the next day. They collect tissue samples of the whale to try and gather information on how it lived, and how it died. For this whale, they also took the whale’s mandibles - or jaw bones - complete with rows of teeth.
“We can have the teeth cut in half,” Flannery says, “and researchers can read the growth layer groups and be able to tell how old it was.”
Preparing the Skeleton
Whale bones in museums and aquariums are gunk free. But preparing bone specimens is messy work. There’s muscles and connective tissue and skin to clean off. There are a couple of different ways to do that: you can soak them in water and let bacteria break down the soft stuff in a process called maceration; you can also use flesh-eating dermestid beetles.
“The dermestid beetles will eat the dry muscles of the bones,” Flannery tells me, “and you end up with nice clean bones.”
Flannery takes me to the part of the Academy of Sciences where these processes take place. It’s informally called the bones lab, and it’s located outside by the loading dock because of the room’s smell. Bones are everywhere - there are sea otter skulls macerating in buckets, bits of minke whale, and snake skeletons being picked clean by dermestid beetles. There are bins of baleen drying in salt and a big murky, gurgling, 300-gallon tank for cleaning larger bones. It uses salt water from the aquarium to macerate some of the specimens.
There’s part of sperm whale’s jaw bone in that tank. But not all of it. Flannery estimates that these fused mandibles weigh somewhere between 800 and 1,000 pounds. They’re too big to macerate and too big for beetles. So there’s a third option - burying them.
“The compost from the dirt material, and the manure that's in the dirt,” Flannery says, “along with the bacteria from the muscles will eventually break down the muscles.”
But for bones this big, it’s going to take at least a year to be cleaned. Which begs the question: where do you bury two gigantic whale bones when you’re located inside Golden Gate Park?
The answer is: the roof. The roof of the Cal Academy is made up of small verdant hills that insulate the building and capture rain water. The bones are placed on the grass on the living roof and then covered with manure, dirt, and soil. It all seems very Bay Area - utilizing an eco-friendly roof to hide decomposing whale bones away from urban coyotes and scavenging raccoons - all for an educational purpose. As Moe tells me, the mound on the roof that has the mandibles is “beautifully planted now,” with plants and flowers growing strong from nutrient-rich soil. It looks akin to a burial mound. Visitors to the roof wouldn’t be able to automatically identify this strange lump of dirt as the resting place for massive sperm whale bones - but that’s why there are docents on the roof to help draw attention to what lies underneath.
No Clear Answers
We’ll never know the exact reason why the sperm whale in Pacifica died. Its tissue sample was too decomposed for scientists to come up with a conclusive answer. As Flannery sees it, the recent number of dead whales we’ve seen on our shores can’t be linked to one central issue.They've died from a variety of human and non-human related causes - like ship strikes, fishing net entanglements and orca attacks. And while these numbers of whale deaths are alarming for people to witness, according to Flannery, in a way they can also be kind of a good thing. These strandings allow us to bear witness to the enormity of these creatures, to the totality of their death, and our role in their well-being.
Visitors to the California Academy of Sciences can catch an entire exhibit devoted to the ocean’s largest mammals. It's called “Whales: Giants of the Deep” and it's on display through November 29th.