Dragons in the series are similar to dragons in many real-world mythologies, although they are divided into different "breeds", with differences in coloration, size, skeletal structure, etc. All (with the exception of sea serpents, which are thought to be a separate species) have wings and the ability to fly, even those that mass up to fifty tons (this is said to be partly due to their bodies' compartments of lighter-than-air gas; "weight" figures represent overall mass, and a fifty-ton dragon might show a mere ten tons on a scale). Dragons are shown to be intelligent and sapient, although the degree of their intelligence varies from sufficient to understand a few words up to being able to compose epic poetry. Dragons are typically born with the ability to speak. They learn languages while still in their eggs, and can speak any language they are sufficiently exposed to during that time fluently from birth. Throughout the series, it is stated that particularly intelligent dragons can continue to acquire languages quickly throughout their entire lives. In the wild, dragons usually have their own languages, and this is shown a number of times when "feral" dragons are encountered throughout the series. Generally, all dragons are depicted as helplessly possessive, attracted to shiny objects, property, and hoarding treasure whenever and wherever possible. This materialistic behavior also extends to people.