The Mystery of Sea Creatures (5/5): The fantastically weird world of photosynthetic sea slugs | Michael Middlebrooks

Sea slugs, specifically those capable of photosynthesis, challenge the traditional biological distinction between plants and animals. While most animals rely on consuming organic matter for energy, certain invertebrates like corals, jellyfish, and specific sea slugs form symbiotic relationships with algae or steal chloroplasts—a process known as kleptoplasty—to generate their own biological energy from sunlight. Invertebrate zoologist Michael Middlebrooks highlights how these creatures, particularly sacoglossan sea slugs, integrate stolen chloroplasts into their own cells to survive for months without traditional food sources. This phenomenon, which includes the ability to synthesize chlorophyll, remains a complex biological mystery that researchers are currently investigating at cellular and molecular levels. These findings expand the understanding of metabolic diversity and evolutionary adaptation in marine ecosystems, revealing how some organisms bypass standard energy consumption pathways.