Meet the sensory biologist studying an “invisible” language

When Dr. Rebecka Sepela was a kid, she performed kitchen table science experiments with her grandfather. He was a product chemist and encouraged Sepela to be curious about the powerful role that chemicals play in everything.

Inspired by the potential for great impact and driven by strong internal curiosity, Sepela studied chemistry and nutrition in college, which introduced her to the world of research science, then biophysics, and finally to sensory biology. Today, she is a postdoctoral fellow in the Belleno Lab at Harvard University working as a sensory biologist studying how microbes influence animal behavior using the octopus as a model.

“In the lab we like to think about the octopus as an animal that is sticking its arms into areas that are unknown,” Sepela said, “and that same kind of principle is very pertinent to my scientific journey.” For the octopus — as well as any scientist — there is no way to know ahead of time what will result from exploring new places.

When an octopus is in search of food, it reaches its highly sensitive, sucker-covered arms into the nooks and crannies of its seafloor environment. In the absence of visual cues, the octopus has to rely on other senses to identify whether the object it touches is a tasty living crab, an inedible decaying crab, or even just a rock.

Sepela wondered how an octopus knew the difference between these interesting and inane surfaces. What sensory cues was the octopus receiving from the object through its sucker cups that signals whether it was edible? She suspected that chemical cues were driving this behavior, but the origin of the chemicals was unclear. The answers lied once again, in biology.

“Because we’ve all evolved in this microbial world, if we’re able to understand how microbes communicate with animals, we could think about all of the processes microbes influence and start to think how we could tweak and tune those processes,” she said.

She tested whether the microbes growing on these surfaces informed octopus behavior and was able to identify specific microbial chemicals that influenced octopus behavior. This result has profound implications not just for understanding octopus behavior, but also in developing a framework for understanding how all animals learn about their world through the microbes around them. Microbes coat every surface and are constantly producing chemicals and octopuses are constantly interacting with their microbial environment.

Like all questions in basic biology, investigating the sensory world of the octopus does much more than help us understand these fascinating invertebrates of the deep. Microbes are fundamental players in the existence and function of most living things, from nitrogen-fixing bacteria in the roots of plants to the complex microbiome of the human gut. By examining the octopus and its microbial friends, Sepela’s research actually asks fundamental questions about how living things exist in a shared chemical world.

Studying these interactions “gives us a glimpse into probably the most universal language between different organisms,” Sepela said. And if scientists can understand that chemical language, they can “start to speak it and use it for the benefit of society.”

Though there have been many twists and turns in her scientific journey since her kitchen table experiments, Sepela has never lost the playful joy that drew her to science in the first place. Her favorite part of this stage of her career as a postdoctoral researcher is that she gets to spend every moment of her day immersed in science. She relishes the hours she spends in a coffee shop at a table littered with scientific papers. She gets excited by the late nights at the microscope and the afternoons in the lab with her mentees. All of the hard work, the circuitous path to get her to her postdoctoral work, has allowed her to do what she loves all the time: be a scientist.

Specifically, Sepela loves being a biologist. “I think the fun part about biology is it is kind of like the wild west,” Sepela said. The creativity necessary for her biological research is a mirror of how living things evolve in their environments. “In sensory biology, each animal has had to adapt to its own unique environment,” she said. “So there’s a lot of motivation in biology to be creative.”

Another favorite part of her work is sharing her love of science with those earlier in their careers. Sepela is one of five 2025 awardees of the L’Oréal USA For Women in Science Program. She is using the award, in part, to further the ability of her lab to help junior scientists develop their research skills and science communication skills.

The junior scientists she mentors are integral to her world. “They ask questions that I don’t ask, they challenge me to explain things in different ways, and I, in turn, challenge them to try new things,” Sepela said. “The one thing that really connects us all is the desire to ask questions. In supporting the next generation as well as helping me to continue to reach out to those who might not interact with scientists, I think this [program] is going to be really transformative.”

_{Filmed in part at the Harvard Museum of Natural History}