The term poecilogony was coined by Alfred Mathieu Giard to describe a polymorphism in larval development in marine invertebrates.
To date, this life history trait is only known in a small number of polychaete taxa,[1] as well as some sacoglossan mollusks.
In some cases, the variation in larval type is a 'plastic' trait in that it is environmentally mediated.
In other cases, the larval type is genetically determined - a good example is the polychaete Streblospio benedicti, where some mothers release small planktotrophic eggs and other mothers release large lecithotrophic eggs.
[2] In either case, the variation in larval type generally involves the production of larvae that differ in feeding mode and/or developmental time.