Jellyfish are enemies in Aqua Boy. There are two types.
Jellyfish are white with two visible long tentacles that hang on either side of their dome-shaped body. Additional small tentacles are seen underneath the body and are red coloured.
Jellyfish remain stationary for the duration of the game and only attack when Aqua Boy is visible on the same screen as them. While they are stationary, they remain in one place by moving their tentacles up and down. Every few seconds, a jellyfish will fire bullets at Aqua Boy. These bullets subtract health.
To defeat a jellyfish, Aqua Boy can use his pistol to fire bullets until it fades into the background and disappears. This can also be done with two maxcharge blasts directly onto the jellyfish. When a jellyfish dies, it sometimes leaves a pickup in its place, such as a heart of health or a charge pickup.
There are two types of jellyfish, determined by their colour. Each attack in a different manner.
- Red jellyfish - Jellies with red tentacles fire bullets outward in a circular shape.
- Blue jellyfish - Jellyfish with blue tentacles fire bullets at a faster rate than the red ones. Rather than firing a set of spread out bullets, they attack with a concentration of bullets aimed in Aqua Boy's direction.