Photosynthetic Sea Slugs: Yes, It's a Big Deal

"Green Sea Slug Is Part Animal, Part Plant"
Wired Science (January 11, 2010)

"It's easy being green for a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant.

"Shaped like a leaf itself, the slug Elysia chlorotica already has a reputation for kidnapping the photosynthesizing organelles and some genes from algae. Now it turns out that the slug has acquired enough stolen goods to make an entire plant chemical-making pathway work inside an animal body, says Sidney K. Pierce of the University of South Florida in Tampa.

"The slugs can manufacture the most common form of chlorophyll, the green pigment in plants that captures energy from sunlight, Pierce reported January 7 at the annual meeting of the Society for Integrative and Comparative Biology. Pierce used a radioactive tracer to show that the slugs were making the pigment, called chlorophyll a, themselves and not simply relying on chlorophyll reserves stolen from the algae the slugs dine on...."

Photosynthetic animals isn't a particularly new idea. Homo sapiens sapiens, for example, uses sunlight to synthesize 'vitamin D' from 7-dehydrocholesterol. ("Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D: integral components of the vitamin D endocrine system1,2," Anthony W Norman, American Society for Clinical Nutrition 67:1108–10 (1998))

Which apparently is why I've got a genetic melanin deficiency. My ancestors lived in northwestern Europe for quite a long time - so all I have to do is expose my face to sunlight for a few minutes a day, and I'm good to go. Leave me out in the sun for too long, and I get radiation burns - but I'm getting off-topic.

Where was I? A green sea slug. Shaped like a leaf. Produces chlorophyll. Right.

Scientists have known for quite a while that these sea slugs can eat algae, break the plant cells down to their component parts and install photosynthetic components inside the sea slug's cells.

What's remarkable is that the genes from algae have been found in unhatched sea slugs. Those slugs didn't eat the plant parts. They inherited genetic coding for making them from their parents.

Which is a whole different ball game.

Exciting: and another piece in the puzzle of how life on Earth works.