Q&A: How a Turtle With Fake Limbs Got a Leg Up

Five years ago, a group of fishers discovered Yu, a loggerhead sea turtle, off the coast of Japan.

She was severely injured, having lost both her front limbs. But an intrepid group of scientists, including  members of industry and University of Tokyo researcher Katsufumi Sato, one of National Geographic’s 2009 emerging explorers, has developed and tested a pair of prosthetic limbs for Yu to help her swim better. (National Geographic News is part of the National Geographic Society.)

Now 25, Yu was recently fitted with her 27th pair of prosthetic flippers at her home, the Suma Aqualife Park in Kobe, Japan.

The molded plastic limbs are attached to a jacket that fits over Yu’s shell. The stubs of her existing front limbs are inserted into the prosthetics so that Yu can swim using the same motions and muscles that she did before her attack. (See related pictures: “Fake Limbs, More Help Animals Heal.”)

Karin Hayashi, one of the scientists who helped test the prosthetics and who just completed her master’s degree at the University of Tokyo, sat down with National Geographic to share more about how she built the turtle’s artificial limbs and what’s next for Yu.

Q: How did the turtle get injured?

A: The turtle was probably injured by a shark attack. When it was found, there were many marks of shark bites on its carapace [back of its shell].

How did it come to your attention?

I was studying about behaviors of sea turtles, using an animal-borne recorder, which could record behaviors of animals under natural conditions at the University of Tokyo. The Sea Turtle Association of Japan, who established a project to create artificial fins for the injured turtle, asked my supervisor, Dr. Sato, to measure the swimming ability of the injured turtle using the animal-borne recorder. And Dr. Sato gave me the opportunity to join the project.

Yu swims after receiving her 27th pair of prosthetic flippers at the Suma Aqualife Park in Kobe, Japan, on February 11. Photograph from Suma Aqualife Park via Reuters

What made you think of creating prosthetic limbs for the turtle?

Dr. Kamezaki, the head of the Sea Turtle Association of Japan, thought of releasing the injured turtle to the ocean at first. However, one [school]boy entreated Dr. Kamezaki to help the turtle because he was worried that the turtle could not survive another shark attack with the injured limbs. Being provoked by the boy’s passion to help the injured turtle, Dr. Kamezaki started the artificial-fins project that purposes to recover [her] swimming ability by attaching artificial fins, which have been developed by Kawamura Gishi Co., Ltd [a Japanese company that designs prosthetics].

Have there been an increasing number of animals getting prosthetics recently? If so, why?

Yes, I think so. I think the reason for that could be an improvement of techniques to create prosthetics for humans so that they could also apply the techniques to injured animals. Another reason could be that because people were more interested in animal conservation. (See sea turtle pictures.)

How do the limbs work?

Sea turtles generate thrust to swim forward by moving their forelimbs up and down like wings of birds. Also, female turtles use their forelimbs to move on land for breeding. Thus, the functions of forelimbs are important for sea turtles’ locomotion.  (Also read about Digital Nomad Andrew Evans’s experience with a turtle with a fake flipper.)

What were you hoping to accomplish by giving the turtle artificial limbs?

We were hoping that the injured turtle became able to swim and move on land like healthy turtles with the artificial fins.

How does the turtle seem to like its new limbs?

When the artificial fins are applied to the injured turtle, she stays calm and seems not to care about [being] attached to the fins. However, her swim speed has not been improved, unfortunately, with the artificial fins so far.

What’s next for the turtle?

The most recent artificial fins were attached to a jacket-like suit slipped over the head of the injured turtle. However, we [were] concerned that she could not swim efficiently because of the increased drag produced from the jacket. The members of the artificial-fins project are working on a new method of attaching the artificial fins to her.

This Q&A has been edited for length and content.

Changing Planet

Carrie is a freelance science writer living in Virginia. When she's not writing about cool critters, she's spending time outside, drinking coffee, or knitting. You can visit her website at http://www.carriearnold.com