Professionals who twist long, skinny balloons into fun animal shapes use a variety of terms to refer to them. Mostly they are called "animal balloons," but some that are either fatter or skinnier than the standard size are called "air ships," "pencils" or "spaghetti balloons."
Specialty balloons in unique shapes and designs can be purchased from balloon manufacturers. Some of the available shapes include squiggly worms, caterpillars, mouse heads, donuts, flowers, people and flying saucers. Sheets of Mylar, or foil balloon material, can be cut into individual shapes and sealed using no more than a household iron.
Balloons used for scientific research are made from neoprene or polyethylene. They are partially filled with gas on the ground, then as the balloon rises, the gas expands until it fills out the balloon. A balloon's volume may become 30 to 200 times what it was on the ground. Neoprene balloons rise until their internal pressure becomes too much and they burst, leaving its instruments to float back to earth with a parachute. Super-pressure and zero-pressure balloons, on the other hand, are made to rise to a certain altitude and remain there until the sun sets and the gas cools, allowing the balloon to descend again.
Giant helium-filled balloons have been a staple of parades for decades. These balloons come as cartoon characters, animal, clowns, airplanes and more, and may be anywhere from 8 feet to 60 feet long. They can be customized with the name or logo of a business. They have to be tethered by several lines to keep them from floating away during a parade.
Large balloons have been used to carry people since 1783. Most such balloons float using hot air. Hydrogen has been used in the past, but it is dangerous; helium is safe but expensive. Propane burners heat the air inside a fabric envelope. The air expands and begins to rise, filling the balloon and carrying along a basket with passengers inside. Hot air ballooning is still a favorite pastime.