Biomechanical structure of the seahorse tail as an inspiration for industrial design

On May 28th Tomas Praet defended his PhD entitled 'Biomechanical structure of the seahorse tail as an inspiration for industrial design'.

 

Millions of years of evolutionary pressure have forced organisms to find suitable solutions for a whole range of real-world problems. Through evolution, small changes in functionality are tested on their fitness, efficiency, and robustness. Engineers are on a daily basis faced by the same problems. Consequently, engineers can find design inspiration in the solutions provided by nature, even for cuttingedge engineering applications.

 


One example of an organism that adapted to its environment in a very specific way is the seahorse. Most fish use undulatory locomotion: the body and tail perform lateral cyclic motions that propel the fish forward. A smaller amount of fish, including the seahorses, use fin undulation as main source of propulsion. These are usually fish that require high manoeuvrability at low speed. The tail of the seahorse has completely lost its function in locomotion: the animal relies on undulation of the dorsal and pectoral fins for propulsion. The use of fin undulation conveniently renders the seahorse very manoeuvrable in its natural habitat of corals and seagrasses, but also turns it into a relatively slow swimmer. Therefore, seahorses are unlikely to escape any predatory fish. They survive by relying on crypsis: they move slowly, while their colours are often adapted to the environment. They also have an armour plating that covers the
body and tail, which likely increases resilience against predatory bites. Despite the strong and stiff shielding, the seahorse tail is still sufficiently flexible to be used as a prehensile organ. With its tail the seahorse anchors itself to objects and vegetation on the seabed, as to avoid being carried away by strong currents, or to a partner during mating.

 


The combination of compressive stiffness and ventral bending flexibility is an interesting achievement of the seahorse tail, especially from an engineering point of view. Combining stiffness in one direction with flexibility in another is a common requirement in engineering designs, one that is often difficult to achieve. In this dissertation we therefore study the biomechanical structure of the seahorse tail. Acquiring profound insights in the mechanics involved will provide design inspiration for various engineering applications that require both flexibility and stiffness.