US scientists have bioengineered a "jellyfish" that can swim, using rat heart cells and silicone polymers.
However rather than being simply a freak of science, the researchers say the creature replicates the human heart and is a good model to study cardiac physiology.
The artificial jellyfish, dubbed Medusoid, was created by a team of researchers at Harvard University and the California Institute of Technology.
Amazingly, the creature swims in water, much like an actual jellyfish.
Similar to the way a human heart moves blood throughout the body, jellyfish propel themselves through the water by pumping. In figuring out how to take apart and then rebuild the primary motor function of a jellyfish, the researchers aim to gain new insights into how such pumps work.
The researchers' method for building the tissue-engineered jellyfish has been published in Nature Biotechnology.
Study researcher Kevin Kit Parker, a bioengineer at Harvard University was spurred to create the artificial jellyfish due to his frustrations with the state of the cardiac field.
"I started looking at marine organisms that pump to survive. Then I saw a jellyfish at the New England Aquarium and I immediately noted both similarities and differences between how the jellyfish and the human heart pump."
A sheet of cultured rat heart muscle, which contracts when electrically stimulated in a liquid environment, was the perfect raw material to create the jellyfish, the researchers said.
A silicone polymer was then used to fashion the sheet into a thin membrane that resembles a small jellyfish, with eight arm-like appendages.
Medusoid was then placed in container of salt water and shocked into swimming with synchronised muscle contractions that mimic those of real jellyfish.
"I was surprised that with relatively few components - a silicone base and cells that we arranged - we were able to reproduce some pretty complex swimming and feeding behaviours that you see in biological jellyfish," John Dabiri, a professor of aeronautics and bioengineering at Caltech, said.
The researchers said the design strategy will be broadly applicable to the reverse engineering of muscular organs in humans.
Parker said cells were simply "another kind of building substrate", like steel, copper or concrete.
"But we need rigorous quantitative design specs to move tissue engineering to a reproducible type of engineering. The jellyfish provides a design algorithm for reverse engineering an organ's function and developing quantitative design and performance specifications. We can complete the full exercise of the engineer's design process: design, build, and test."
Janna Nawroth, a doctoral student in biology at Caltech and lead author of the study, said a goal of the study was to advance tissue engineering.
"In many ways, it is still a very qualitative art, with people trying to copy a tissue or organ just based on what they think is important or what they see as the major components - without necessarily understanding if those components are relevant to the desired function or without analysing first how different materials could be used."
The researchers aim to further evolve the artificial jellyfish, allowing it to turn and move in a particular direction, and even incorporating a simple "brain" so it can respond to its environment and replicate more advanced behaviours, like heading toward a light source and seeking energy or food.