Pet prosthesis - Dolphin recovers swimming ability with artificial fin

Bridgestone has developed a rubber fin for a dolphin that lost most of its tail fin to disease. The beneficiary of the technology is Fuji, a 235-kilogram 2.7 metre female at the Okinawa Churaumi Aquarium. Fuji has regained nearly all of her swimming ability since receiving the new fin in what is believed to be the first-ever successful development of an artificial fin for a dolphin. Fuji has been in the Aquarium for 28 years, and the oldest of her three offspring, Ryu, 26 years of age, is the Japanese record holder for dolphin lifespan completely under human care. Fuji contracted the disease that caused progressive deterioration of her tail fin from the edge in October 2002. Amputating most of the fin saved Fuji’s life but left her unable to swim well. Volunteers at Bridgestone went to work on the rubber fin for Fuji in December 2002 and the company subsequently assembled a project team to tap the full range of Bridgestone’s rubber technology. The team delivered its first prototype in September 2003 and followed up with a second prototype the next month.

Graduate school of Engineering, Department of Environmental and Ocean Engineering at the University of Tokyo supported the development effort by conducting numerous numbers of tests on the rubber fin in their special water tank, and the project team delivered a third prototype in March 2004. The further improvements enabled Fuji to regain her swimming ability. The miraculously rejuvenated Fuji returned to public view at the Churaumi Aquarium from July 19. Since August, she has been delighting her keepers, visitors, and the Bridgestone engineers with jumps that carry her completely out of the water.

The Bridgestone developed fin is of silicone rubber, a material that is highly compatible with living tissue. It has a cushion of patented foamed rubber called, “Everlight Moran,” where it fits against the dolphin’s body because of its excellence in the resistance against water and climate. ACM (Advanced Composite Material) provides reinforcement for the fin, and reduces the load on Fuji because of its light weight comparing to the metal. The Bridgestone engineers analyzed the movement of dolphin fins in three dimensions and FEM (finite element method) used for designing tires to optimize the fin design.

The use of company’s material development, rubber design, and analysis technology helped creating the artificial fin for dolphin.