Reptile Researcher

Kenro Kusumi explores the secrets behind the astounding abilities of reptiles

©2021 ARIZONA BOARD OF REGENTS/ARIZONA STATE UNIVERSITY. USED WITH PERMISSION

IN THE FIELD: Kenro Kusumi (in orange) and colleagues examine a Mojave Desert tortoise.

Many small reptiles, like geckos and iguanas, can regrow lost tails. Biologist Kenro Kusumi wondered if their bigger relative—the American alligator—could also regenerate a severed tail.

©2021 ARIZONA BOARD OF REGENTS/ARIZONA STATE UNIVERSITY. USED WITH PERMISSION

To find out, Kusumi examined several unusual alligator tails in his lab at Arizona State University. The appendages shared features like abnormal coloring and flexible cartilage tissue at their core instead of the usual bone. These characteristics indicated that the tails had, in fact, regrown. The discovery makes alligators the largest animals known to have the ability to regenerate a body part.

Kusumi investigates adaptations that help reptiles survive. A big part of his work involves studying and decoding the genomes of various reptiles. A genome is the complete set of an organism’s genetic material. Kusumi spoke with Science World about how such research is advancing scientists’ understanding of reptiles, including their powers of regeneration, and helping protect species under threat.

Why is it important to study genomes?

An organism’s genome consists of information coded in its DNA—the molecule that carries hereditary information. DNA determines how an animal looks, behaves, and functions. Genomes are incredibly complex. For example, it takes 6 billion pieces of genetic information to encode a human.

Genome biologists want to decipher organisms’ genetic codes to learn more about them. But we don’t fully understand how genomes work. The genomes of animals on Earth today developed over billions of years as organisms evolved, or changed over time. Figuring out the details of their genomes is going to take time.

What prompted you to study reptiles?

There are four groups of vertebrates, or animals with backbones, that live on land: amphibians, birds, mammals, and reptiles. Of these, reptiles have some of the most varied body shapes, behaviors, and habitats where they live.

And reptiles do some really cool things! Some tortoises live up to 200 years. Other reptiles can go dormant, or mostly inactive, for six months to survive the winter. Many can regrow body parts. Studying reptile genomes could help us understand how the regeneration process works and suggest ideas for how to apply it in medical treatments for people someday.

© MILLARD H. SHARP/SCIENCE SOURCE (ALLIGATOR); SHUTTERSTOCK.COM (GECKO)

REPLACEMENT TAILS: Kusumi has found that American alligators (top) have the same ability to regrow a severed tail as smaller lizards like geckos (bottom).

How can genome research help protect threatened species?

Genome research can help scientists evaluate the genetic diversity—the different genetic characteristics—of threatened populations. Then people can understand why a  species behaves the way it does, how it might deal with changing environmental conditions, and how it might respond to diseases. For example, the Mojave Desert tortoise, which is under threat, can suffer from respiratory disease. We hope that our work decoding its genome could point the way to developing tests for this type of illness. Then conservationists can monitor the disease and determine how to better manage it in the wild.

If we don’t take action, some threatened reptiles may disappear forever. That can be bad for their entire ecosystem—a community of organisms interacting with their physical environment. Some tortoises, for example, are really good diggers. In areas like the Southeastern U.S. that experience a lot of wildfires, gopher tortoises live in burrows that can double as shelters for other animals when an area burns.

©2021 ARIZONA BOARD OF REGENTS/ARIZONA STATE UNIVERSITY. USED WITH PERMISSION

TORTOISE TRACKING: A GPS tracker (dark gray bump on shell) allows scientists to follow the animal’s movements.

When did you realize you wanted to be a scientist?

I had this incredible 7th-grade biology teacher. She put students in touch with the volunteer program at the local museum of natural history. I learned about field biology, taking care of live animals such as snakes and insects on display, and how to prepare exhibits. That got me on my way to becoming a scientist myself.

What advice do you have for teens who are considering becoming scientists?

Curiosity is key to being a scientist. It’s also important to have scientists from all backgrounds and cultures who bring their own unique perspectives to the table. We need lots of different voices asking their own unique questions in the future.

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