Aiden Salk | January 16th, 2025

Animals and organisms all over the world fit into their own ecological niche — “the role an organism plays in a community.” Some organisms, like bioluminescent anglerfish, have increased their chances for survival through evolution of traits so they can best outcompete their competitors for food, placing them in distinct ecological niches. Interestingly, one family of fish has developed entire leg-like appendages to help them hunt: sea robins, a type of fish in the Triglidae family.

When sea robins first hatch, they have webbed fins and no leg appendages. Eventually, their legs stem from their pectoral fin bones that make up the webbing. Phenomenally, the first three fin rays on either side begin to separate from the rest of their webbed fin during maturation. A mature sea robin will thus have two webbed pectoral fins and three leg-equivalent appendages on each side. As sea robins’ legs develop, their growth is accompanied by a change in their musculature and neural connections. 

Sea robins often use their legs to “walk” rather than swim, which may be more efficient than swimming in areas with strong currents. They also use them to search for prey hidden in sand on the seafloor. In fact, one species of sea robins, called northern sea robins (Prionotus carolinus) even have sensory papillae coating their legs. Papillae are the same as the bumps on one’s tongue that house taste buds, and the sensory papillae on sea robins’ legs have taste receptors. This provides a chemical sensitivity that provokes sea robins to dig for prey buried deep below the seafloor. The mechanisms and cellular basis for the northern sea robin’s sensory adaptations are yet to be understood, but it is exciting how much more we can learn about these fascinating organisms.

Credit: Bryant, K. (2014). Licensed under CC-BY-2.0. Leopard Sea Robin (Prionotus scitulus) [Photograph]. Flickr. https://www.flickr.com/photos/mentalblock/14674580701.

References

Allard, C. A. H., Herbert, A. L., Kingsley, D. M., & Bellono, N. W. (2023). Sea robins. Current Biology, 33(13). https://doi.org/10.1016/j.cub.2023.04.015 

National Geographic. Niche. Education. https://education.nationalgeographic.org/resource/niche/

ScienceDaily. (2024, September 26). These fish use legs to taste the seafloor. ScienceDaily. https://www.sciencedaily.com/releases/2024/09/240926132111.htm