A jellyfish has no fins or muscles for steering — instead its bell (the dome-shaped body) works like a pump. Radial muscles contract the bell, squeezing water out through the opening underneath; when the muscles relax, elastic mesoglea springs the bell back to its resting shape and it refills. Each contraction fires a slug of water backward, and by Newton's third law the animal is pushed forward — the same jet-propulsion principle that drives a squid or a rocket.
Thrust scales with how fast the bell's volume is changing, not just how far it contracts: a quick, sharp contraction ejects water faster and produces more thrust than a slow one of the same depth. That is why the live "Jet thrust" readout below spikes right as each bell snaps shut and drops to near zero while it is relaxing and refilling.
- Population — how many jellyfish are drawn and animated at once.
- Bell size — scales each animal's dome and, with it, the volume of water it can displace per pulse.
- Pulse speed — the contraction frequency; faster pulsing means more but weaker thrust spikes per second.
- Bioluminescence — every contraction briefly brightens the glow, mimicking how many real jellies flash light when disturbed or feeding.