Samantha Andrews

Marine biologist/ecologist and a science and environmental writer. She can be found talking or writing about our Earth in all its splendour—including the people and other animals who live here —and achieving a more sustainable future.

Tossed tails: New study finds surprising twist in salamander tail regeneration

June 11, 2019 | 2 minute read

A tail is a very important thing for a salamander. It stores fats and proteins, assists with movement, and not to mention, helps to impress a mate. But the tail can also work to deter predators. Should a salamander find itself faced with a predator such as a snake, it can try to make itself too big to be eaten by grabbing the end of its tail with its mouth. A handy trick, but not as impressive as the salamander’s grand finale; salamanders can self-amputate their tails.

“If a predator strikes, the tail is left writhing and wriggling on the ground. This distracts the predator long enough that the body can escape” said Dr. Aaron Sullivan, co-author of a new study published in the Canadian Journal of Zoology.

Being able to drop a “zombie-tail” clearly has survival benefits, but so too does having a tail in the first place. For the encore, their pièce de résistance—tail regeneration. It’s an energy-intensive process, meaning salamanders need to balance everyday energy needs with the additional energy requirements needed for growth. So, can salamanders control that growth to account for their circumstances?

“Wes Payette, the lead author, thought salamanders would be able to mobilize their resources to grow a tail relatively fast if they thought the threat of predation was high,” Sullivan explained. However, sometimes in science what we think will happen is not what happens.

As Payette and Sullivan report, tail growth rates are impacted by the threat of predation—just not in the direction the researchers were expecting. When they exposed a group of autotomised (tail-amputated) captive Allegheny Mountain dusky salamanders to snake kairomones—chemical cues from snakes and other animals—to simulate high predation threat and compared tail regrowth against a control group, they found the salamanders exposed to kairomones didn’t regrow as much of their tail as their un-threatened counterparts. “We were wrong—and that’s kind of cool!” Sullivan said.

Payette and Sullivan don’t know the causes of this surprising result, though they suspect that the very mechanism that they thought would induce faster growth—stress—may be the thing that inhibits it.

“What we’ve potentially done is exposed animals to more stress than they’re accustomed to experiencing over a five- or six-month span,” said Sullivan. “If you invest more energy into responding to elevated threats, then there has to be a trade off somewhere. Growth and healing and immunosuppression seem to be the trade-offs.”

For Sullivan, the surprising results are not the only exciting part of this study. Sullivan works at an undergraduate teaching institute, not a research institute. Payette was one of Sullivan’s undergraduate students. Another one of his students, Jacqi Lewis, is currently investigating the role of stress hormones in tail regrowth. Both studies were prompted by the questions and ideas curated by Payette and Lewis. “That’s what makes science fun,” Sullivan said. “We can talk and we can read, but importantly we can actually do the science too.”

Read the full study: The effect of predator kairomones on caudal regeneration by Allegheny Mountain Dusky Salamanders (Desmognathus ochrophaeus) in the Canadian Journal of Zoology.

Samantha Andrews

Marine biologist/ecologist and a science and environmental writer. She can be found talking or writing about our Earth in all its splendour—including the people and other animals who live here —and achieving a more sustainable future.