Sharks' spiral-shaped intestines resemble a Nikola Tesla invention

By Christa Lesté-Lasserre

A CT scan of the spiral intestine of a Pacific spiny dogfish shark (Squalus suckleyi)

Samantha Leigh/California State

Sharks person spiral-shaped intestines that enactment successful a akin mode to an antithetic valve designed by Nikola Tesla. Studying their anatomy could assistance amended concern fluid-pump technology.

Most animals person tubular intestines that usage musculus contractions to propulsion nutrient on similar squeezing a conduit of toothpaste. But sharks dilatory transmission their meals done spirals without needing muscles to propulsion the food. Their intestines are besides shaped successful a mode that lone allows nutrient to travel 1 mode – similar a performance-enhanced Tesla valve, says Samantha Leigh astatine California State University Dominguez Hills.

“Sharks person each these antithetic small tweaks to the Tesla valve plan that could beryllium making them much efficient,” she says.

Leigh and her colleagues surgically removed the full digestive tubes from 32 dormant sharks that had either been donated to their task oregon conserved successful the Natural History Museum of Los Angeles County, representing 22 shark families. Each has 1 of 4 antithetic kinds of spiral intestine: columnar, which looks similar a spiral staircase; scroll, which looks similar a rolled-up expanse of paper; and 2 types with either upward-facing oregon downward-facing funnels.

The researchers filled each the intestines with fluid and freeze-dried them to support their earthy signifier earlier scanning them utilizing computed tomography. From those scans, they created virtual 3D models, offering the archetypal glimpse of however these “natural” Tesla valves are structured and function, says Leigh.

Then, utilizing an unfrozen illustration of each of the 4 types of intestine, the researchers recovered that liquids took astir 35 minutes to tally done the spirals successful the mean absorption of flow. However, erstwhile they turned the spiral intestines upside down – other the mean travel – liquids took up to doubly arsenic agelong to walk done the 2 funnel types arsenic they did previously.

The squad besides tested spiral intestine relation successful 5 precocious euthanised Pacific spiny dogfish sharks (Squalus suckleyi) by moving coloured liquids of assorted thicknesses done the spirals. Because the sharks had conscionable died, their spiral muscles inactive reacted to the beingness of the liquid. The researchers determined that these contractions “mix and churn” fluids arsenic opposed to pushing them along, says Leigh. “Just the operation of the intestine itself volition bash that enactment of moving things on unidirectionally.”

Shark-inspired exertion could beryllium particularly utile for industries requiring travel moving successful 1 absorption with minimal vigor use, similar filtering microplastics from discarded water, she says.

While scientists inactive don’t cognize wherefore sharks person these peculiar intestines, they fishy they mightiness extract the maximum magnitude of nutrients from food, helping them past for weeks without a meal, says Leigh.

Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2021.1359

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