How a brilliant-green sea slug manages to live for months at a time 'feeding' on sunlight, like a plant, is clarified in a recent study. The authors present the first direct evidence that the emerald green sea slug's chromosomes have some genes that come from the algae it eats.

...These genes help sustain photosynthetic processes inside the slug that provide it with all the food it needs.

Importantly, this is one of the only known examples of functional gene transfer from one multicellular species to another, which is the goal of gene therapy to correct genetically based diseases in humans.

"Is a sea slug a good [biological model] for a human therapy? Probably not. But figuring out the mechanism of this naturally occurring gene transfer could be extremely instructive for future medical applications," says study co-author Sidney K. Pierce, an emeritus professor at University of South Florida and at University of Maryland, College Park.

This biological adaptation is also a mechanism of rapid evolution, Pierce says. "When a successful transfer of genes between species occurs, evolution can basically happen from one generation to the next," he notes, rather than over an evolutionary timescale of thousands of years.