Elysia clarki is a species of sacoglossan sea slug, a marine gastropod mollusk in the family Plakobranchidae. The slug lives in the Florida Keys in near-shore. Elysia clarki attains relatively large size (up to 35 mm). Unlike the case for many Elysia species, which are tiny. Elysia clarki is a relatively cryptic species (has cryptic coloration). It inhabits low wave energy habitats, such as mangrove swamps, borrow pits, and mooring canals. It feeds suctorially on several species of siphonaceous green algae including Penicillus capitatus, Penicillus lamourouxii, Halimeda incrassata, Bryopsis plumosa, and Derbesia tenissima. The slug sequesters the chloroplasts from all of these species and uses them for photosynthesis. Furthermore, Elysia clarki photosynthesizes using the stored chloroplasts for up to three months without ingesting food. This species is one of the so-called 'solar-powered sea slugs'. Elysia clarki is an excellent organism for evaluating the relationship between kleptoplasty and feeding behavior, because observations of feeding behavior and measurements of photosynthesis are possible with Elysia clarki. Its photosynthetic capability (because of its kleptoplasty) has been shown to affect its foraging behavior under starvation conditions. 2011 was the first time that this connection was demonstrated for any organism within the animal kingdom. This article incorporates CC-BY-2.5 text from the reference