In a remarkable discovery that sheds new light on marine adaptation, scientists have found that clownfish — made famous by the movie Finding Nemo — can shrink their bodies to survive extreme heatwaves and avoid social conflict. The research, published in Science Advances, was led by Newcastle University, in collaboration with universities in Leeds, Boston, and Papua New Guinea.
Over a five-month period, scientists tracked 134 clownfish in Kimbe Bay, Papua New Guinea, during a marine heatwave. They found that 100 of the fish physically shrank, not just losing weight but actually becoming shorter in length. This unprecedented shrinking boosted survival rates during heat stress by up to 78%.
“We were so surprised to see shrinking in these fish that, to be sure, we measured each individual repeatedly,” said Melissa Versteeg, lead author and PhD researcher at Newcastle University. “This isn’t just about getting thinner—these fish are getting shorter, possibly through bone resorption, like marine iguanas.”
Interestingly, the study also revealed that synchronized shrinking between breeding partners further increased survival odds, suggesting that social coordination plays a key role in adapting to stress.
Dr. Theresa Rueger, senior author of the study, noted, “This phenomenon could help explain why the average size of fish is declining globally. If shrinking is happening across other species too, it challenges our current understanding of how climate change is affecting marine life.”
As climate-driven marine heatwaves become more frequent, these findings open new avenues for understanding how marine species are evolving to cope—and highlight the urgent need for continued ocean monitoring and conservation efforts.