what i used in this sentence: rhetorical question or irony and why

the species will disappear faster than a Houdini magic trick

This sentence uses irony. Irony is used to express something that is the opposite of what is expected or intended. In this case, the sentence is expressing that the species will disappear quickly, comparing it to the famously fast disappearances performed by illusionist Houdini, which is ironic because Houdini's tricks are known for being impressive and quick.