Skip to main content

KNOXVILLE — Whether they admit it or not, many parents may have tried to act a little younger to fit in with their children’s social networks. But for some members of the animal kingdom, resembling the younger generation might be their best shot at survival.

Colin Sumrall

Colin D. Sumrall, a lecturer in the University of Tennessee’s Department of Earth and Planetary Sciences, will be discussing this phenomenon, called paedomorphism, Friday at the UT Science Forum. Sumrall’s lecture, “The Secret of the Starfish: How One Arm Could Become 4 or 2,” will take a closer look at the evolutional development of starfish and how paedomorphism plays an active role.

“Paedomorphism basically means adults that are evolved to look more like the juveniles,” he said. “But this is one of the best examples that there is of paedomorphism being a major driving force in the evolutionary process.”

Sumrall’s research of starfish, which are the modern-day representations of a group of organisms known as echinoderms, shows that organisms in this group tend to have “an overwhelming love of the number five,” thus the basis of their body plan. But Sumrall said dozens of times throughout history, these organisms have genetically altered their usual growth formation, leaving some adults with fewer than five arms, but resembling younger species.

“A lot of the large scale taxonomy of these animals is based on this reduction in arm number,” Sumrall said. “It’s very important from the perspective of understanding the evolutionary history of the group and how we interpret them.”

But it is also key to the organism’s survival, he said.

“Instead of sticking up in the water like they normally would, some actually lie on the sea floor. Adjusting the number of arms helps them be a flattened animal,” and thus less likely to be preyed upon.

Sumrall said much of his research is purely of academic interest, but he hopes attendees will gain a better understanding of the evolutionary process and what it can mean today.

The UT Science Forum is a weekly, non-technical lecture and discussion designed to help others better understand research across many disciplines. It is held every Friday at noon in Thompson-Boling Arena, dining rooms C and D. Attendees may bring their own lunch or purchase it at the arena. Each presentation should last around 40 minutes followed by a question and answer session.

Additional upcoming Science Forums follow:

— “The Renaissance of Nuclear Power in the United States,” Friday, March 10, Jeffery Binder, Senior R&D program manager, Oak Ridge National Laboratory.
— “Can a Robot Have a Mind?” Friday, March 17, Bruce MacLennan, associate professor of computer science.
— “Fusion Energy Research: Status and Outlook,” Friday, March 31, Stanley Milora, director, Fusion Energy Division, Oak Ridge National Laboratory.


Jay Mayfield, media relations (865-974-9409,

Colin D. Sumrall, lecturer, Department of Earth and Planetary Sciences, (865-974-0400,

Mark Littmann, forum organizer, (865-974-8156,