The use of a part to represent the whole, or the whole to represent a part, as in 'All hands on deck,' is an example of

Synecdoche is a figure of speech in which a part ('hands') is used to represent the whole (the sailors or crew). Metonymy substitutes the name of one thing for something closely associated with it, irony involves saying the opposite of what is meant, and apostrophe is a direct address to an absent or imaginary person or thing.