ABSTRACT
Ephemera are things that last – continue or hold out --– for a day or less. If we are thinking rigorously there is nothing ephemeral in nature: flowers are the reproductive organs of certain plants whose life cycles continue beyond their appearance, while the famously short-lived mayfly, whose winged state can last as little as 30 minutes, first spends a year in its larval stage. More than this, the ephemeroptera, the order of insects to which the mayfly belongs, dates back 300 million years. Before we call an organism ephemeral we must decide where and when it begins or ends, and to do this we will have to follow the paths of evolutionary biology into a field from which there is no easy exit.
