Despite having a rather unspectacular name, sea slugs are quite possibly some of the most bizarre creatures found in nature. Remember ‘Shaun the Sheep‘, the adorable sea slug with floppy feelers and beady eyes that looks like a cartoon lamb? According to a new research, bizarre doesn’t even cover it when it comes to Elysia chlorotica, a green sea slug species, and its behavior.
Also known as the photosynthesizing sea slug, this leaf-shaped being can survive for months on sunlight much like green plants. How a marine invertebrate manages to do that has long baffled the scientific world. As part of the new study, researchers have revealed that the sea slug is capable of photosynthesis, thanks to specific genes stolen from the algae it consumes. Speaking about the find, recently published in The Biological Bulletin, Sidney K. Pierce of the University of South Florida said:
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.
Chloroplasts, as we already know, are organelles, commonly found in algal and plant cells, which contain chlorophyll, a group of green pigments responsible for absorbing energy from sunlight. That Elysia chlorotica incorporates chloroplasts from the alga Vaucheria litorea into its own DNA has been known to scientists since the 1970s, though the exact mechanism of this fascinating phenomenon was a mystery until now.
After acquiring them from the algae it has just eaten, the sea slug embeds the plant organelles into its own digestive cells, which in turn enables it to produce food through photosynthesis for up to nine months. For the current research, the team was trying to figure out how these beings manage to keep the stolen chloroplasts functional for such long periods of time. Using highly-specialized DNA amplification, sequencing as well as imaging technologies, the researchers were able to discover algal genes for chlorophyll synthesis as well as chloroplast proteins in the slug’s own genome. Pierce went on to explain:
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… 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.
This, according to the scientists, is actually one of the few known examples of functional gene transfer between multicellular organisms. Pierce went on to say:
When a successful transfer of genes between species occurs, evolution can basically happen from one generation to the next.
Source: Marine Biological Laboratory