These fish have evolved legs to help them find and taste buried food.

A striking fish living on the bottom of the Atlantic Ocean has evolved legs, but not just for walking. This appendage is a new tongue-like sensory organ that is used to find food buried on the sea floor.

Northern robin (Prionotus carolinus) It has three legs on each side of its body and protrudes from the base of its pectoral fin. The legs are derived from structures within the pectoral fins called dorsal rays.

I went on a research trip to Woods Hole, Massachusetts. Nicholas Bellono After hearing about the hunting prowess of sea robins, a team of researchers at Harvard University decided to bring a few live specimens to their lab.

The team wanted to find out whether the fish were as adept at finding food as they were renowned for. “Surprisingly, they were very adept and were even able to find capsules filled with ground and filtered mussel extract and single amino acids,” Bellono said.

The researchers then collected more fish, but found that the second batch were adept at walking but failed to detect prey buried in the sand.

“This new sea robin found nothing, even though it readily consumed food on the surface,” says Bellono. “We thought we were doing something wrong, and it turns out we just happened to get a different species.”

The team is looking for a banded sea robin (Prionotus evolans), Although they walk, they are specialized for hunting buried prey.

“When we compared burrowing and non-burrowing animals, the legs were clearly different and the sensory papillae on the burrowing legs were clearly visible,” says Bellono.

These projections are similar to those made up of taste buds on the human tongue and are projections that contain taste receptors and neurons sensitive to touch.

A variety of other fish have also evolved modified pectoral and pelvic fins to help them walk or sit, the team says. Amy Herbert from Stanford University, California. “But a unique feature of the sea robin is that while other fish typically use their entire pectoral or pelvic fins for this purpose, the sea robin’s legs can move independently and very quickly, making them particularly adept at walking and digging. . “She says.

The team also examined the genes that drove the evolution of the robin’s unique legs and found that their development was controlled by ancient regulatory genes. tbx3a.

“It is typically expressed in specific regional regions of the fins and limb buds of all animals, from fish to mammals,” the team member says. david kingsleyIt’s also at Stanford University. “This is a great example of modifying old, shared tools to create new body parts.”