It is common knowledge that multicellular organisms that perform photosynthesis are plants or marine algae. However, in the marine kingdom, a special group of sea slugs (Sacoglossa) has mastered the art of stealing chloroplasts from their algal food and keeping them functional within their animal cells for hours, days, weeks, or even several months! These stolen chloroplasts are often called kleptoplasts, and the mechanisms that allow these sea slugs to accomplish such a feat are still not fully understood by the scientific community.

At CESAM-UA, a team of researchers from the Marine Biotechnology and Aquaculture research group has been trying to elucidate this remarkable association between sea slugs and algal chloroplasts. The principal investigator leading this effort is Sónia Cruz, who recently received a €2.3 million grant from the ERC to solve this enigma. Together with Paulo Cartaxana, they have been conducting various experiments with photobiology tools to better understand if and how biomolecules derived from photosynthesis improve the performance of sea slugs. The state-of-the-art facilities at CEPAM-ECOMARE (University of Aveiro), supervised by Ricardo Calado (director of B2E), have enabled the use of recirculated life support systems, operated with synthetic seawater under highly controlled conditions, to maintain and breed several of these solar-powered sea slugs originating from Portuguese, Mediterranean, and Caribbean waters. The biological material produced under controlled conditions allowed Rosário Domingues and Felisa Rey to gain unprecedented insight into the lipidomics of these sea slugs using mass spectrometry approaches and revealed the fundamental roles that lipids play in the ability of these animals to retain functional kleptoplasts within their animal cells.

The team led by Sónia Cruz intends to present a project that allows functional chloroplasts to be kept outside of plant/algae cells and incorporated into animal tissues or other non-organic matrices. The potential applications of this research are multiple and could be revolutionary. These solar-powered sea slugs may well add a green tint to the ongoing blue revolution, driven by marine biotechnology, towards more sustainable bioeconomic models.