The robo-human-fish also features a simple pacemaker-like mechanism that autonomously regulates the frequency and rhythm of these contractions so the tail has a proper back-and-forth motion to propel it through the water. Without any additional inputs, the muscle cells functioned as a closed-loop system and were able to propel the fish for over 100 days. Furthermore, like the muscles in your body improving with exercise, the biohybrid fish got better and better at swimming as time went on, until it was able to move through the water at speeds similar to a zebrafish.
The prospect of an aquarium full of artificial fish you rarely have to feed is a tempting one for those who are notoriously irresponsible at taking care of pets, but the researchers have loftier goals. Successfully recreating the biophysics of the heart’s function, and the self-sustaining mechanisms that make it endlessly beat, is a huge step towards one day being able to create artificial hearts from the same organic ingredients our bodies use.