Giant Crab Exoskeleton in Exile 25 Years Returns to Rutgers Geology Museum
Biological artist Bruce Mohn, whose passion is the preservation of animal species, will put it back together
Just inside the door of the Core Repository on the Livingston Campus – where the Department of Earth and Planetary Sciences stores earth cores for study – lies the exoskeleton of a giant spider crab. Most of the crab rests on its original frame, with a box of disconnected parts nearby.
The crab, which stretches more than eight feet from claw to claw and whose carapace is the size of a baseball catcher’s chest protector, was sent to the repository more than two decades ago from the Rutgers University Geology Museum, where it had hung on the wall for nearly a century. By the early 1980s, it had begun to deteriorate.
“Visitors had begun to take little pieces of it as souvenirs,” said Lauren Neitzke-Adamo, the museum’s associate director.
The museum had hoped to restore the crab, believed to be a gift to the university from the Japanese government in the late 19th century, but it lacked the funds – that is, until recent donations.
“We’ve decided to restore the crab as part of a larger project to renovate the museum,” Neitzke-Adamo said. “Membership contributions have given us enough to get us started, and we hope to raise enough money from the public to finish the job.” 
Bruce Mohn will put the crab back together. Mohn is the laboratory operations coordinator for the Division of Life Sciences in the School of Arts and Sciences. But in his spare time, he pursues his passion; the reconstruction and preservation of animal specimens, both living and extinct.
Since he was a child, Mohn has been interested in nature and art and sought a career in which he could combine both. He studied biology and art in college, adding to and polishing his skills. In 1993 he began doing artwork for museums. His work is now on exhibit in museums around the world.
Mohn considers himself a professional biological artist. Besides reconstructing animals like the crab, he sculpts and illustrates a variety of biological subjects, including plants and insects.
But in this case, he said, it’s best to call him a preparator, someone who readies specimens for study and exhibit.
First, Mohn will have to take the crab off its mounting and disassemble it. “I can’t think of a good way to get it into my Corolla otherwise,” he said. Once he has it home, he’ll wash it with lacquer thinner, removing what’s left of the lacquer with which the Japanese donors coated it more than a century ago.
Then he’ll take the crab outside and paint the entire exoskeleton with a solution of acetone and glue. The exoskeleton absorbs the acetone and the glue with it, allowing the glue to hold the exoskeleton together. Because acetone is highly toxic if inhaled or absorbed through the skin, as well highly flammable, Mohn performs this operation outside, wearing gloves and a gas mask, and makes sure the mixture has just enough acetone and no more. 
Once the solution sets and the exoskeleton dries, Mohn will repeat the process with the interior of its appendages. After the exoskeleton dries and sets again, Mohn can re-mount it on its frame. One claw and a piece of the carapace are missing; Mohn will sculpt those parts.
Because this work often takes place in his front yard, it often attracts the neighbors’ attention. “They’re pretty much used to it,” Mohn said. “But the crab will be nothing, compared to the fossilized tyrannosaur foot I worked on a few years ago.”
The crab is scheduled to return to the museum sometime before the spring of 2013, when it will once again spread its appendages across the gallery wall, overlooking the mastodon.