January 3, 2011
Meet Dermestes maculatus: The Burke Museums flesh-eating volunteers
They slave away by the thousands in private, quietly giving their lives for science. No, not graduate students, they are members of the Dermestes maculatus species — otherwise known as flesh-eating beetles. And they help the UWs Burke Museum with a sensitive and important job.
The Burke Museum of Natural History and Culture has about 50,000 mammal specimens in its collection, most of which come from collectors or were used in research projects. But the museum also has a long and trusting relationship with Seattles Woodland Park Zoo. Occasionally when an animal there dies, its remains will be sent to the Burke for research purposes.
But such specimens — animal remains or parts thereof — need to be thoroughly cleaned first. The beetles do this job like they were born to it, as indeed they were.
“They are unpaid volunteers who sacrifice their lives,” said Jim Kenagy, professor emeritus of biology and the Burkes curator of mammals. “They live and die and breed and the larvae are propagated. Its a reproducing colony of beetles.” The size of the colony varies, he said, roughly between 5,000 and 10,000 insects.
Zoo staff alert the Burke when an animal of interest to the museum is about to be euthanized, or has died of natural causes. The one who maintains that close connection is Jeff Bradley, the Burkes mammalogy collection manager.
“Theyve got a list on file of species were interested in, and its basically everything in their collections Ive clicked yes, well take it,” Bradley said. “Well probably take anything, at minimum a skull and tissue specimen.”
Kenagy said the museum is interested in fresh tissue from such animals as well as their skeletons. “We take some of that and put it into our frozen tissue collection, where its stored at minus 80 degrees centigrade for possible DNA extraction and analysis.” Thats part of the museums Genetic Resources Collection, “and thats why its critical to get some of that tissue right away, after death,” he said.
“Many of these species are very hard to find in museums,” Bradley said, “particularly in frozen tissue collections (museums didnt start collecting tissue until the past couple of decades), and they add considerably to the Burkes current library of animal tissues.” He added, “Once curated at the Burke, they are included in our online database and available to researchers anywhere in the world.”
For the beetles to begin their work, the remains must be dried and prepared. Internal organs are removed, Kenagy said. “Using knives and cleaning tools, big chunks of meat and muscle are cut away and discarded.” The stripped-down skeleton is then dried in a well-ventilated area. “Then they are finally placed — with this very small amount of dried muscle and connective tissue — into the beetle colony, where the beetles have at them.”
The length of the beetles job depends largely on the size of the specimen theyre cleaning. The remains of Gertie, who weighed about 5,000 lbs., have been months in preparation. For the tiniest mammals such as shrews, or hummingbirds, “it would be on the order of a day or two,” Kenagy said.
The beetles do such a thorough job they have to be monitored. “You take a shrew skeleton or a small rodent, you have to be careful to get it out quickly because very thin ribs and delicate processes can actually be destroyed by the beetles if you leave them in too long,” Kenagy said. They cant chew through thick solid bone, but make quick work of cartilage and small, delicate bones.
Bradley said the museum uses a weak ammonia solution to “degrease” the bones of specimens, “so the bones wont be tacky or sticky to the touch.” But grease and oils also help keep the bones intact, so this process, too, is monitored. “You can make them too dry, and then they wont last as long.”
Such painstakingly-prepared animal specimens have many research uses, including comparing different species, or animals within the same species. “Genetic resources are an important part of our zoology collections at the Burke,” Kenagy said. “The anatomy of the skull in particular, or an entire skeleton, can be used for studies in systematics and naming species, comparing closely related species — and nowadays this is used hand-in-hand with DNA evidence as well, as thats become such an important part of the way we study evolutionary biology and the phylogenetic, or relatedness, measures between species and higher level organizations of animals.”
The museums collections are of interest to researchers across the campus and even the country. “Over time one cant even say who all that might be. In that sense, any museum collection is like a library — its for scholars to use on some present or future occasion,” Kenagy said.
But for all the talk of flesh-eating bugs, he said the most compelling part of the work remains people-oriented. “Its the excitement of knowing that youre bringing together a combination of things that are valuable to many people — its bringing people together around collections that makes it fun to work in museums.”
It takes a lot of work to get remains from the zoo to the Burke and cremation is less expensive. Thats why Bradley works, he said, to “make it as easy as possible for the zoo to give us things.”
Its a sad and emotional event for zoo staff when an animal dies. But the Burkes respectful process of processing the remains for research — with the aid of thousands of loyal Dermestes maculatus — gives added value to the lives, and afterlives, of what some at the museum fondly call “emeritus members of the Woodland Park Zoo.”