In a fluid heat transfers when

In fluids, heat is often transferred by convection, in which the motion of the fluid itself carries heat from one place to another.

Another way to transfer heat is by conduction, which does not involve any motion of a substance, but rather is a transfer of energy within a substance (or between substances in contact).

Meaning its either by convection or conduction !

Hope this helps!

themselves

an intensive pronoun is a pronoun that ends in self or selves, such as himself, herself, themselves, yourself, ourselves. since band members is a third person plural, the correct intensive pronoun would be themselves. if the band was talked about as a collective noun, itself would be the appropriate intensive pronoun. intensive pronouns are used to add emphasis to the noun it's modifying which is why it directly follows it.