The ability to transform light energy into chemical fuel is typically associated with plants and algae. However, in rare cases, animals show this ability, too. Several species of Sacoglossan sea slugs, for instance, can co-opt the photosynthetic ability of the algae they feed on. The slugs accomplish this by retaining rather than digesting the algac's chloroplasts, the cell parts primarily responsible for photosynthesis. The chloroplasts continue to photosynthesize even after they are assimilated, a curious phenomenon that forces us to reconsider our assumptions about what animals are capable ofWhat is the main idea of the given passage?
1) Animals can also transform light energy into chemical fuel.
2) Sacoglossan sea slugs retain and use the photosynthetic ability of algae.
3) Chloroplasts in animals continue to photosynthesize after assimilation.
4) The ability of animals to photosynthesize challenges our assumptions.
