Fungi, like most plants, are immobile and so to reach any new habitat they must either grow into new areas, often too costly a method, or find a way to disperse seeds so that they can find their way into new hospitable environments.
Although fungal spores are smaller and lighter than plant seeds they still face many issues. First it is difficult for them to use the wind, because many do not ground far enough off the ground to be above the still air that is next to the ground. To overcome this and other barriers fungi have developed ways to use their surroundings to their own advantage including wind, animals and water, which are passive methods of spore dispersal.
Wind
Some fungi create spores that can be carried on the wind. The giant puffball serves as an example of this because it forms a crack to allow spores to be carried away on the wind. Although this can be an effective method there are several cons as well. First the chance of success is low because the odds of the spores landing in hospitable environments are now very high. Also the fungi must produce many extra seeds just to allow for the possible that just a few of them will be successful. This means that for that small chance a lot of energy is used by the fungi. Another problem is that many spores do not get carried very far, resulting in overcrowding near the parent plants and a lack of dispersal.
Water
Some fungi use water instead of wind by dispersing spores that float by not absorbing the way that many fungi will. These spores are carried along on the surface of the water. Raindrops can also serve to help disperse spores in a different way than streams or rivers. In a puffball mushroom that uses water to help with the release raindrops is often the method to burst the sack containing spores. When a rain drop lands on the ball of the fungi it bursts releasing the spores.
Animals
A fungus that serves as an excellent example of animal dispersion is truffles. Truffles develop under the ground and when they are mature they release a scent that attracts animals that then dig up the truffle for food. The spores pass through their digestive systems undigested will pass out of the animal, hopefully at a good distance from where the original truffle was dug up. Using animals as a dispersion method greatly improves the chance that a spore will end up a good distance away from the parent organism.
