To date, scientists have explored less than 10% of the ocean and have knowledge of over 230,000 species. With 700 million years of evolution under their belts, jellyfish have had quite a while to evolve and perfect the craft of survival. Jellyfish are the oldest multicellular organism to still exist today but understanding their evolution is difficult as jellyfish don’t have any hard parts or bones to make fossils. However, what we do know is that jellyfish were the first fish to begin to swim against the ocean’s current.
As a naturally-occuring model of underwater movement, jellyfish movement is studied in the aim to improve the movement of underwater vehicles. With one of the most economical methods of underwater propulsion, jellyfish have shown researchers that flexibility is a key ingredient in efficient underwater movement. Different jellyfish move in different ways, the two main being jet propulsion and ciliary propulsion. Jet propulsion consists of a thrust in the opposite direction of movement - jellyfish relax their bell-shaped bodies and then contract to expel water creating a thrust that propels them froward. Similarly, ciliary propulsion (used by comb jellyfish) is the continuous beating of cilia that propels the jellyfish forward. These forms of propulsions cause a field of high pressure behind the jellyfish.
Later, scientists such as John Dabiri, found out jellyfish also have a field of low pressure before them which aids in their thrust. So jellyfish suck themselves forward? Yes, jellyfish move via dual propulsion, they actually create a suction vortex that aids in the jet/ciliary propulsion.
Jellyfish’s ability to use move through the ocean efficiently (10 to 100 times more than other animals) is of great interest to mechanical engineers as they can use jellyfish as inspiration for independent mechanisms that be utilised in isolated settings with little manipulation i.e. marine robots or pumps in the human body. Marine robots inspired by jellyfish could be used in the ocean to monitor ocean quality (such as temperature, pH and other metrics).
The reach of jellyfish admiration has not been limited to the sea, but in fact has influenced the design of flight vehicles. Biomimetic engineering has found that that jellyfish propulsion is very beneficial to airborne machines. The Applied Math Lab at New York University implored the mechanisms of the jellyfish when they created a drone that can hover with no need for extra sails or tails. The machine is a small and light machine measuring approximately 10cm in length and weighing no more than a few grams.
With all new inventions in science, thought needs to be given to the implication of the research. Inventors of the flying machine advocate its usefulness in surveillance (as it can be controlled remotely for long periods of time) and in air and traffic monitoring. As the mechanical flexibility is improved, such machines are thought to be able to manoeuver into small spaces, further advancing their potential.
It seems that jellyfish, in spite of their bad reputation, are really clever animals, and can be considered animals of the past, present and future. Jellyfish are making the best of every bad situation, guaranteeing their survival for many more centuries. It is no wonder that jellyfish are the bioinspiration for energy-efficient mechanics.
More on jellyfish:
Bio-inspired underwater propulsors by Tyler Van Buren, Daniel Floryan and Alexander Smits
Stable hovering of a jellyfish-like flying machine (paper) by Leif Ristroph and Stephen Childress
Jellyfish have superpowers… (article) by The Conversation
The JellyBiologists (blog)
By Tomi Akingbade, Founder