A recessive genetic disorder caused some 'blasters to be born with very short side spikes in a certain area of the population. These were at a disadvantage during courtship, as the males could not fight over females without proper spikes. These runts would be left at the back of mating circles to fight on their own, and they only thing they could do was blast air at each other, but without spikes to act as support, they would be more propelled forwards than shoot water or air at each other. Demonstrations of butt-power (and with that, speed) turned into races and the runts split from the buttblasters to become the bumblasters.
The bumblasters are built for speed, and can outrun a majority of predators on the plains, every so often making a BANG! and shooting forward with their blasters. The tip of the nose has split and gone to the front of the blasting organ, letting air flow through the nostrils, and into the organ efficiently. The nostrils are big and take in lots of air, which also helps by making the bumblaster hyper.
They will use their blasters for courting, with multiple males circling females with various "bangs" sounding out across the local area as they try to gain speed or blow others out of the circuit. They live in small groups or alone, and only make a herd during mating season. Pregnant females are very vulnerable, and rely on the males to attempt to protect them from predators with loud noises or simple offensive. After the children are born, they will try to stick close to their mothers until they come of age and leave on their own.