Have you ever wished that instead of cooking you could just sit in the sun for a few hours and feed off of sunlight the way a plant does? There is a green sea slug that has managed to do just that, for months at a time and how the animal does this is even more remarkable.

In a study published in the Biological Bulletin, researchers present the first direct evidence that the emerald green sea slug has adopted some of the genes from the algae it eats. Specifically these genes help sustain the photosynthetic process and allow the animal to ‘eat’ sunlight.

This is one of only a few known examples of genes transferring from one species to another. The phenomenon will no doubt be of interest to people working on gene therapy for humans as well as the genetic modification of other organisms.

“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,” said study co-author Sidney K. Pierce, an emeritus professor at University of South Florida and at University of Maryland, College Park in a statement.

The researchers used advanced imaging to confirm that the gene from the Vaucheria litorea algae is present in the Elysia chlorotica sea slug’s chromosome. The gene makes an enzyme that is necessary for photosynthetic machines called chloroplasts.

There has been considerable debate and intensive studies to attempt to determine how the slug manages to make the photosynthesizing organelles function for longer than the plant would be able to.

“This paper confirms that one of several algal genes needed to repair damage to chloroplasts, and keep them functioning, is present on the slug chromosome. The gene is incorporated into the slug chromosome and transmitted to the next generation of slugs,” says Pierce.

In short each new generation of slugs must acquire their own chloroplasts from algae, but the genetic ‘engine’ that keeps the chloroplasts functioning is genetically inherited.

“There is no way on earth that genes from an alga should work inside an animal cell, and yet here, they do. They allow the animal to rely on sunshine for its nutrition. So if something happens to their food source, they have a way of not starving to death until they find more algae to eat,” says Pierce.

According to Pierce the biological adaptation is also a mechanism of rapid evolution.

“When a successful transfer of genes between species occurs, evolution can basically happen from one generation to the next,” he notes.

More information about how an animal has managed to integrate and use genes from a plant, will no doubt help researchers who are working on similar problems in gene therapy and gene therapy.