kleptoplasty

thumb |upright=1.2 |A digestive tubule cell of the sea slug Elysia clarki, packed with chloroplasts taken from green algae. C = [[chloroplast, N = cell nucleus. Electron micrograph: scale bar is 3 μm.]]

Kleptoplasty or kleptoplastidy is a process in symbiotic relationships whereby plastids, notably chloroplasts from algae, are sequestered by the host. The word is derived from Kleptes (κλέπτης) which is Greek for thief. The algae is eaten normally and partially digested, leaving the plastid intact. The plastids are maintained within the host, temporarily continuing photosynthesis and benefiting the host.