"Super sense" discovered

What else this fish can do with its “little legs”

(Bild: kameraOne (Screenshot))

The gurnards - their name comes from the growling noises they make with their swim bladder - are unusual fish. Among other things, they have six elongated fin rays that look like little legs, which they use to "walk" across the seabed. Researchers have now made another discovery.

Gurnards are bottom-dwelling marine fish. They are found in all shelf seas and prefer to live on sandy or soft bottoms, where they use their elongated fin rays ("legs") to poke around for food. The animals live in water depths of up to 400 meters.

Track down prey in the sand with pinpoint accuracy
Two new studies have now shown that the "legs" are not only used for walking on the seabed, but that they also function as sensory organs with which the gurnards detect prey buried in the sand, such as mussels and other shellfish - a true "super sense".

The six legs are actually extensions of the gurnards' pectoral fins.

(Bild: kameraOne (Screenshot))

The six legs are actually extensions of their pectoral fins, of which they have three on each side. Biologists have long suspected that the legs of the gurnard are not only good for running and digging. A team led by Corey Allard from Harvard University therefore examined the animals more closely under laboratory conditions.

Legs are covered with papillae
The scientists discovered that the animals can use their legs to accurately detect ground and filtered mussel extract and even individual amino acids in the sand of a tank. As it turned out, the six legs of the gurnards are covered with so-called papillae - small wart-shaped protrusions of the skin. These are strikingly similar to the papillae on the human tongue, in which taste buds and taste receptors are bundled.

"This is a fish that evolved legs using genes that also contribute to the development of our limbs, and then repurposed those legs to find prey using the same genes that our tongue uses to taste food - pretty crazy," says Nicholas Bellono from Harvard University in Massachusetts, describing the discovery.

The researchers hope that this genetic overlap between humans and fish may help to clarify how our species developed the upright gait around six million years ago.