Sea robins are strange animals: they have the body of a fish, the wings of a bird and the legs of a crab. Now, a study has discovered that their legs are not only used for walking, but also They help them find and taste buried prey.
“The legs of this fish are one of the strangest things I’ve ever seen“says David Kingsley, a developmental biologist at Stanford University, in the newspaper The New York Times.
“This is a fish that grew legs thanks to the genes that help the development of our limbs and then reused them to find prey using the same genes that our tongue uses to taste food: a real madness“summarizes Nicholas Bellono, from Harvard University (Cambridge, Massachusetts).
After discovering these animals by chance during a visit to the Woods Hole Marine Biological Laboratory in Massachusetts, researchers They were curious and wanted to study them better.
These fish They are very good at finding food.which is why other opportunistic fish always follow them, but it was not yet known why they had this ability.
By studying them, Kingsley’s team discovered that their legs are covered with sensory papillaeeach of which receives a dense innervation of touch-sensitive neurons. In addition, these papillae also have taste receptors and a chemical sensitivity that prompts them to dig.
A genetic study
Later, in a second study, the researchers delved into the genetic basis of the unique legs of these fish. First, they used genome sequencing and the study of hybrid species to understand the molecular and developmental bases of leg formation.
Their analyzes identified an ancient and conserved genecalled tbx3a, as the main determinant of the sensory development of the legs of sea robins.
Genome editing confirmed that these fish depend on this gene regulator to normally develop its legs. Likewise, the same gene also plays a fundamental role in the formation of the sensory papillae of sea robins and in their burrowing behavior.
“Although many traits appear new, they are often built from genes and modules that “They have been around for a long time.”because “that’s how evolution works: tinkering with old parts to build new things,” says Kingsley.
