The MP2Lab study “Loss of state transitions in Bryopsidales macroalgae and kleptoplastic sea slugs (Gastropoda, Sacoglossa)” published in the journal Communications Biology has been highlighted in CESAM audiovisual series “Abstract”. In this video (T1Ep.9), first author Vesa Havurinne explains that a common light acclimation mechanism in green algae ‒ State Transitions ‒ has been lost in Bryopsidales, an order of green macroalgae. The study also shows that photosynthetic sea slugs feeding on other ulvophyte algae that do exhibit strong state transitions lose this capacity due to structural changes in the chloroplasts occurring during the incorporation by the animal cells. Enforced chloroplast sphericity may represent a fundamental property of functional kleptoplasty in photosynthetic sea slugs.