Mutations are odd effects that resulted from exposure to mutagenic radiation, nanoscopic machines (nano-bots) or retro-viruses (the last two being standard mutagenic elements from the 6th edition, while the first is typical for most editions).
Some mutations may not be given for some types of mutant animals and plants, if its part of their nature (e.g. bats have sonar, wings, and poor eye-sight, and would be apart of a mutant bat's abilities, even if they are not noted).
A number of similar mutations have been condensed into single pages for the ease of use and site-management, with keywords linking to their common article. For example, Abnormal Size includes the Shorter and Taller mutations. Heightened Sense lists the most mutations—which includes all the five senses, plus Directional Sense and Heightened Balance.
Scientific explanations for the mutations and how they work, are not needed, as Gamma World is traditionally a "science fantasy" setting, subject to what is generally called "comic book physics." It should be noted that divine retribution would be imposed on innocent cartoon characters, if this comes to a debate with real-world physics (see the following disruption: God Kills a Catgirl).