Clownfish come in a variety of color variations, and now researchers understand how sea anemones impact that color pattern. A new study published in the peer-reviewed journal PNAS unravels the symbiotic relationship between sea anemones and clownfish, revealing that it extends beyond mere coexistence and into ecological diversification.

DISL Senior Marine Scientist and University of Alabama faculty member Dr. Benjamin Titus contributed to the publication titled “Host use drives convergent evolution in Clownfish.”

Clownfish are known to live within the venomous tentacles of sea anemones to protect themselves from predators. Once a clownfish decides which sea anemone to call home, moving becomes risky, so the clownfish usually stays put once it has moved in. The two largest clownfish in a single sea anemone will reproduce in their chosen sea anemone.

Titus and the research team were curious if the species of sea anemone that the clownfish chose to call home impacted the diversification of the clownfish’s appearance. The group analyzed whole genomes, physical traits, and host associations of all 28 clownfish species. What they learned was that the clownfish evolve similar color patterns and body shapes when they use the same types of host anemones, even in different regions.

While this study unravels a mystery in how clownfish get their colors, it will also reshape future research paths for clownfish and the mutualistic relationships between species. In 2022, Dr. Titus presented his preliminary findings of this study during an Alabama Aquarium Boardwalk Talk.