Science Daily goes deep (well, a little deep) on sea robins, the fish known for having little legs they use to scurry across the ocean floor. Apparently those “legs” are actually sense organs these walking fish use to detect buried prey:
“This is a fish that grew legs using the same genes that contribute to the development of our limbs and then repurposed these legs to find prey using the same genes our tongues use to taste food — pretty wild,” says Nicholas Bellono of Harvard University in Cambridge, MA.
Bellono, along with David Kingsley of Stanford University and their colleagues, didn’t set out to study sea robins at all. They came across these creatures on a trip to the Marine Biological Laboratory in Woods Hole, MA. After learning that other fish follow the sea robins around, apparently due to their skills in uncovering buried prey, the researchers became intrigued and took some sea robins back to the lab to find out more. They confirmed that the sea robins could indeed detect and uncover ground-up and filtered mussel extract and even single amino acids.
As reported in one of the two new studies, they found that sea robins’ legs are covered in sensory papillae, each receiving dense innervation from touch-sensitive neurons. The papillae also have taste receptors and show chemical sensitivity that drives the sea robins to dig.
“We were originally struck by the legs that are shared by all sea robins and make them different from most other fish,” Kingsley says. “We were surprised to see how much sea robins differ from each other in sensory structures found on the legs. The system thus displays multiple levels of evolutionary innovation from differences between sea robins and most other fish, differences between sea robin species, and differences in everything from structure and sensory organs to behavior.”
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You can read more about the research here, and here, in Current Biology.