S.T.

June 11, 2022 By David Coppedge



SNIPPET:

Have you ever heard of the “lateral line”? No, it’s not a football play. It’s a sense organ shared by most fish, from sharks to salmon to goldfish.

From 🐟 Gills to Tail

The lateral line has been called a “sixth sense” for fish. It runs from gills to tail along the sides of the fish, right in the middle. You can see it when you catch a trout. Or in the case of a goldfish, it’s visible in the photo above. A page from the University of Minnesota Sea Grant describes this amazing organ:

Sometimes referred to as the “sense of distant touch,” lateral lines convert subtle changes in water pressure into ⚡ electrical pulses similar to the way our inner ear responds to sound waves. Running lengthwise down each side of the body and over the head, these pressure-sensing organs help their owners avoid collisions, participate in schooling behavior, orient to water currents, elude predators, and detect prey.

Lateral lines are composed of neuromasts (hair cells surrounded by a protruding jelly-like cup) that usually lie at the bottom of a visible pit or groove. These hair cells — the same sensory cells found in all vertebrate ears — convert mechanical energy into electrical energy when moved. Presumably, auditory and lateral line pathways evolved in close association since they share many features. [Emphasis added.]

You can shrug off that fish story about how it evolved . What’s remarkable is that this organ constitutes an analog-to-digital converter, as pressure waves (analog) are converted to electrical signals. Actually, we all have that capability in our skin, as Science reports — a fact that has inspired Stanford engineers to create “electronic skin”:

Human skin relies on cutaneous receptors that output digital signals for tactile sensingin which the intensity of stimulation is converted to a series of voltage pulses. We present a power-efficient skin-inspired mechanoreceptor with a flexible organic transistor circuit that transduces pressure into digital frequency signals directly.

Back to fish and the lateral line. News from the University of Florida showed two researchers using lasers to try to understand how the lateral line works. One of them, Dr. James Liao, calls it a “hydrodynamic antenna” that is “configured to receive flow signals,” according to Physical Review Letters. A diagram at Wikipedia shows how many components are involved in this complex sensory apparatus.

Swim Muscles

Another little-known fact about fish is how their muscles are arranged. Have you ever cooked salmon and wondered about those stripes in the muscle? Those are called myomeres. See the good diagrams and photos on Earthlife.net, which points out that “Gram for gram fish have more muscle than any other vertebrate, a male salmon or tuna can be nearly 70 percent muscle, which is one reason why fish are so good to eat.” 😋

Read more:
https://evolutionnews.org/2022/06/lateral-line-a-sixth-sense-for-fish-and-other-cool-tricks/

David Coppedge 👍 is a freelance science reporter in Southern California. He has been a board member of Illustra Media since its founding and serves as their science consultant. He worked at NASA’s Jet Propulsion Laboratory (JPL) for 14 years, on the Cassini mission to Saturn, until he was ousted in 2011 for sharing material on intelligent design, a discriminatory action that led to a nationally publicized court trial in 2012. Discovery Institute supported his case, but a lone judge ruled against him without explanation. A nature photographer, outdoorsman, and musician, David holds B.S. degrees in science education and in physics and gives presentations on ID and other scientific subjects.