Figure 17.2 The green sea slug. When the slug first hatches from an egg, it is brown. However, as it begins to eat algae, it stores the chloroplasts from the algae in its own tissues. As the slug accumulates a large number of chloroplasts, its body turns green and it is able to acquire most of its energy through photosynthesis rather than through herbivory.

Photo by Nicholas E. Curtis and Ray Martinez, University of South Florida.