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AZ: Helping Mr. Stubbs: Midwestern Researcher Helps Develop Prosthetic Alligator Tail

March 12, 2013

by Office of Communications

"Mr. Stubbs" Goes Viral

The story of the alligator with the prosthetic tail has made waves in the national news. Check out some of the coverage so far:


USA Today


The Arizona Republic

CBS Channel 5 Phoenix

With their armored bodies, muscular tails, and powerful jaws, American alligators typically rule the swamps and rivers of the Southeastern United States.

But the tale of one of these reptiles rescued by Phoenix Herpetological Society (PHS) is much different. The alligator now known as "Mr. Stubbs" was missing his tail when he came to PHS, probably losing it to the bite of another gator.

Even though they are heavy and ungainly out of water, American alligators are normally well adapted swimmers. But without a tail, Mr. Stubbs was in danger of drowning in his pond.

"When we first got him, if the water was too deep for him to touch the bottom, he would roll over onto his back and could not right himself," says Russ Johnson, President of PHS. "We had to teach him to swim by dog paddling, like you teach a child to swim."

Thanks to the collaboration between researchers and physicians, Mr. Stubbs can now move like a normal alligator. He has been fitted with a prosthetic tail that took well over a year to develop, in order to create one that was the right size and weight to restore normal posture and movement while walking, and balance in the water.

The tale of the tail

When researchers at The CORE Institute learned about Mr. Stubbs, Dr. Marc Jacofsky and his research associate Sarah Jarvis took on the challenge of improving his mobility and quality of life. A team was assembled and several options were considered for creating a prosthetic tail. Working with researchers at Midwestern University, Dr. Jacofsky and his team determined the ideal size and density of the tail needed to recreate the proper body proportions and weight distribution for Mr. Stubbs.

Justin Georgi, Ph.D., an Assistant Professor of Anatomy in the Arizona College of Osteopathic Medicine at Midwestern University, had been studying the locomotion of alligators, monitor lizards and tortoises at PHS since 2010. He became aware of Mr. Stubbs' plight and, with his Research Assistant Kevin Manfredi, joined the project to help the reptile.

Using several alligator specimens of different sizes from his lab, Dr. Georgi and Samanta Arroyos, a lab intern from the Phoenix Union Bioscience High School, were able to work out the appropriate size of tail for Mr. Stubbs. Based on these measurements, Dr. Georgi provided one of the specimens from his lab as the model for the new tail and consulted on the prosthesis design with Dr. Jacofsky and the team from The CORE Institute.

Donating their work and materials, The CORE Institute created high-resolution molds of the alligator's stump, as well as a full tail of appropriate size. The prosthesis was covered in Dragon Skin®, a lightweight, flexible silicone material often used for special effects and animatronics in films, as well as prosthetics. Next, a replica of the full tail was married to a mold of Mr. Stubbs' posterior. The final step was creating a harness system to securely affix the new prosthetic tail to the alligator's body, without creating any pressure points that could cause discomfort or skin breakdown over time.

The tale appears to have a happy ending: Mr. Stubbs' gait has shown dramatic improvement and he is adapting to his new balance in the water.  But, notes PHS' Johnson, "After almost eight years, we need to 'unteach' him the dog paddle, so he can swim like a normal alligator."

More about the American Alligator

Adult alligators are apex predators that are critical to the biodiversity of their habitat. They feed mainly on fish, turtles, snakes, and small mammals. They have come back from the brink of extinction thanks to state and federal protections, habitat preservation efforts, and reduced demand for alligator products. The species' wild population now numbers more than one million.

More Information

For more information, please contact:
Office of Communications
630.515.7333 (IL) or 623.572.3353 (AZ)