Half-Animal, Half-Plant

Justin Leong

Animals require other organisms to consume in order to produce the necessary nutrients for their survival. Plants produce their own food in a process called photosynthesises, hence the name producers. A sea slug, Elysia chlorotica, has been discovered to be able to carry out eh process of photosynthesis. It has some genetic coding of a plants, and yet the mobility and abilities to be a consumer as well. This is the first animal known to be able to produce its own food. Its versatility can allow it to survive under harsh conditions and food shortages. Its evolution branching off from the sea slug family has made it a very hardy marine gastropod.

Elysia chlorotica has passed down genetic traits that allow it to perform photosynthesis. These traits are stolen from algae that the sea slug eats. Newborn sea slugs need to eat a certain amount of algae before they can perform photosynthesis due to the fact that not all the genetic traits are passed down from the parent. Photosynthesis requires chloroplasts, cells that absorb light and are the keystone to the photosynthesis process. The algae are being consumed by the sea slug, who pierce it and ingest the substance within it, which contain the necessary genes. The sea slugs are extracting the needed genes from the algae and using it themselves. The algae is “stealing” the genes, similar to mimicking an ability of another.

Scientific experiences of putting the sea slug under lights in water, and giving it the light. This experiment shows that the creature is performing photosynthesis because they tested for the CO2 and other molecules being converted into glucose, the food of plants. The energy was used to keep the animal alive. The animal would be able to live in place with only sunlight and water, as well as in darkness with food. The adaptation could allow in to survive in harsh places, but it chooses to reside near its algae food source, Vaucheria litorea, that live in salt and tidal marshes of shallow water with depth less than 0.5 meters.

The Elysia chlorotica has no natural predator or prey, besides the algae it eats for food. Its leaf-shaped body helping blend in with the green sea plants. It just peacefully grazes in the shallow waters. As the 11 month life span of the slug ticks down, in the springtime, right before their death, the adults lay hordes of eggs meant to hatch soon. These will continue the next generation.
The idea of gene editing in humans has been thought of, but these creature do it naturally for their survival. If humans had the ability of photosynthesis, the amount of food eaten and the biological impact left on the earth would be less. Scientists may find out how to change certain genes in order for humans to be like plants. The Elysia chlorotica leaves a small biological print on the earth, something humans should learn to do, and mimic.


1. Blanchet, Chelsea. “Elysia Chlorotica.” Animal Diversity Web, animaldiversity.org/accounts/Elysia_chlorotica/.

2. Moskowitz, Clara. “Surprising Sea Slug Is Half-Plant, Half-Animal.” LiveScience, Purch, 12 Jan. 2010, www.livescience.com/6030-surprising-sea-slug-plant-animal.html.

3. Rogers, S.A. “Bizarre Sea Slug Is Half Plant, Half Animal.” MNN - Mother Nature Network, Mother Nature Network, 31 May 2017, www.mnn.com/earth-matters/animals/stories/bizarre-sea-slug-is-half-plant-half-animal-0.