Great White Sharks May Inspire Faster Planes And Boats

AsianScientist (Sept. 04, 2024) – The great white shark, one of the most efficient predators, known for its power and speed, holds the secret to designing faster aircraft and boats. A new study, published in the Journal of the Royal Society Interface, has revealed how the denticles, or tooth-like structures, on the shark’s skin help reduce friction, allowing sharks to swim with great efficiency at different speeds. This friction reduction is crucial for their speed and endurance, making them swift hunters and long-distance swimmers, travelling distances of up to 20,000 kilometres.

The study, conducted by scientists at the Tokyo Institute of Technology, found that these denticles possess high and low ridges that influence how fast a shark moves. The high ridges are more effective at lower speeds, while a combination of high and low ridges works best at higher speeds, enabling the shark to conserve energy while cruising or hunting.

According to associate professor Hiroto Tanaka, one of the lead authors of the study, this design allows sharks to move efficiently both during slow, steady swimming and when they need to make quick bursts of speed.

These findings can inspire new designs in the engineering world. Engineers have long been intrigued by the denticles of migratory sharks, using them as a model to create riblets — small, unidirectional ridges that reduce friction in aircraft and sailboats. However, the complexity of denticle shapes, sizes and spacing across a shark’s body made it difficult to fully understand how they work together to minimize the movement drag.

To unpack this complexity, the researchers developed 3D models of white shark denticles, analyzing the hydrodynamic properties of the high middle ridges and low side ridges in relation to the shark’s swimming speeds. They found that these structures are optimized to reduce drag across a wide range of speeds, enabling the sharks to have bursts of speed for hunting and to travel long distances by using minimal energy.

For the study, the researchers collected skin samples from 17 different locations on a white shark’s body, including the snout, dorsal fin, lateral and ventral body, caudal fin and pectoral fins from . These samples were scanned using a microfocus X-ray CT scanner to create detailed 3D models. By measuring the spacing and height of the ridges, the researchers were able to determine how effectively the shark’s skin interacts with turbulent vortices in the water. Their findings show that these denticles are designed to reduce drag effectively at both slow cruising speeds and fast hunting speeds.

“High ridges likely reduce drag at low swimming speeds, and high-low alternating ridges reduce drag at high swimming speeds, covering the full range of swimming speeds,” Tanaka said.

The study also suggests that the swimming speeds of the megalodon, an extinct giant shark, might have been similar to those of the great white shark. Apart from new engineering designs, these findings could also help scientists study shark evolution.

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Source: Tokyo Institute of Technology ; Image: Shutterstock

The article can be found at:  Three-dimensional shape of natural riblets in the white shark: Relationship between the denticle morphology and swimming speed of sharks