The impossible claim

This sea slug eats algae exactly once — then steals the machines plants use for photosynthesis and runs on sunlight for ten months.

The verified facts

The eastern emerald elysia (Elysia chlorotica) is a sea slug that does something no animal should be able to do: photosynthesize. It eats the algae Vaucheria litorea exactly once in its life, but instead of digesting the algae completely, it keeps the chloroplasts alive inside its own cells — a trick scientists call kleptoplasty (“plastic theft”).

  • The stolen chloroplasts keep working inside the slug’s digestive gland for up to 10 months, feeding it through photosynthesis — after that one first meal, it may never eat again
  • Its genome contains algal genes that help maintain the chloroplasts (horizontal gene transfer — parts of the algae’s DNA became part of the slug’s)
  • The slug’s body is leaf-shaped and bright green, and its branching digestive gland makes it look exactly like a living leaf — camouflage and solar panel in one
  • Baby slugs are not born green — they only turn solar-powered after their first and only meal

Watch

🎬 See the Short on YouTube — The Animal That Never Eats Again

Sources

  • Rumpho, M. E. et al. (2008). Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica. PNAS.
  • Schwartz, J. A., Curtis, N. E. & Pierce, S. K. (2014). FISH labeling reveals a horizontally transferred algal (Vaucheria litorea) gene in the genome of the sea slug Elysia chlorotica. The Biological Bulletin.
  • Christa, G. et al. (2014). Functional kleptoplasty in limapontioidea: chloroplast retention in a marine slug. Proceedings of the Royal Society B.
  • Pierce, S. K. et al. (2012). Metabolic improvements and protein evidence supporting the acquisition of photosynthesis by the kleptoplastic sea slug. The Biological Bulletin.

Part of Impossible Creatures — every fact verified, every creature real. Watch the Shorts at https://www.youtube.com/shorts/Sv6MKucFdVI.