In metamorphic species, an organism's body plan changes at different points in its life cycle. A. Organisms that metamorphose use resources less efficiently than do organisms with a single body plan. B. Because of the high energy costs associated with metamorphosis, only a few types of niches are rich enough to support metamorphic species. C. The larvae of some population found in extreme environments reproduce at the juvenile stage and never achieve the adult form. D. Metamorphosis enables an organism to make use of environments that are highly productive for a short period of time but not for the organism's entire life span. E. In many metamorphic species, the juvenile stage is focused on eating and growing and the adult stage is focused on dispersal and reproduction. F. Some population remain at the larval stage in part because they lack sufficient nutrition to metamorphose into adults.