Some fish have legs that can taste prey underfoot

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Sea robins are fish with two large, winglike fins and six crablike legs. But their extra limbs do more than just scurry about the seafloor.

Research now suggests that some sea robin legs can sense tastes. The ends of those legs are coated with small bumps called papillae. These sensors work like the taste buds on your tongue. Here, they let the underwater walkers taste prey that are buried under sand.

Researchers shared the new findings October 7. The work appeared in Current Biology.

A graphic tale" with animals drawn around the letters

A grayish brown fish with two large fins sticking out of its sides and three crablike legs on either side of its underbelly stands on the seafloor. In its mouth is the fleshy interior of a mussel, which it has just plucked from an open mussel shell. The fish is thinking, “Om nom nom.”

A grayish brown fish with two large fins on its sides, smaller fins down its back and six thin legs underneath it scuttles across the ocean floor. The fish is called a sea robin.

A sea robin eyes a group of blue and yellow fish following it around as it walks across the seafloor. The three fish surrounding it are all watching the sea robin and thinking, “Food? Food? Food?” Text (below image): That got an international team of scientists curious how these sea robins’ extra limbs help them forage.

Kicking through the sand, the fish homed in on the mussels and treats with mussel pieces. They left the saltwater capsules alone. This hinted that their legs could chemically sense their food.

Their legs, it seemed, lacked the chemical sensing ability of northern sea robins’.

The grayish-brown northern sea robin and the copper-colored striped sea robin drift in a blue background of water. A close-up of one of the northern sea robin’s legs shows that the tip of its leg is covered in little bumps, like those on animal tongues. A close-up of one of the striped sea robin’s legs shows that the tip its leg has no bumps (papillae) like the ones on animal tongues.

A family tree shows how different species of sea robins have branched off from each other over time. Many current species do not have the genes for legs that taste. But two current species do. Those species are the northern sea robin and the leopard sea robin. An illustration below the family tree shows one member of each of these species looking at each other. The leopard sea robin, which is light gray with dark gray spots, says, “You can taste with them, too??” The northern sea robin replies, “Sure can!”

But sea robins’ feat of tasting with their legs is a first for fish.

All panels: JoAnna Wendel

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