The rich green colour of the photosynthesizing sea slug, Elysia chlorotica, helps to camouflage it on the ocean floor. Credit: Patrick Krug.

Researchers have discovered that the sea slug Elysia chlorotica uses genes from algae to gather energy from sunlight.

Genes are instructions for how to build and maintain a body.  The sea slugs have ‘stolen’ instructions for how to look after molecules called chloroplasts, which absorb energy from sunlight.

The chloroplasts give the sea slugs additional energy to live and grow, so they have some energy even when they don’t eat.

It also gives them a bright green colour.  (Sunlight is made up of all the colours of the rainbow; the chloroplasts look green because that’s the only colour they don’t absorb.)

The researchers want to study the slugs some more to find out how the chloroplasts keep working for as long as up to nine months, which is longer than they work for in the algae.