Alien-Like Sea Slug Steals Body Parts to Gain Powers
Imagine a creature that looks like it belongs in an alien salad, but in reality, it’s a bizarre sea slug that has the incredible ability to steal body parts from other organisms and use their powers for itself. Meet the lettuce sea slug (Elysia crispata), a fascinating marine creature that defies conventional biology.
Instead of just digesting food like most organisms, the lettuce sea slug feeds on algae and then separates out the algae’s photosynthesizing organelles, known as chloroplasts. These chloroplasts are then used by the slug almost like tiny solar panels, harnessing energy from sunlight. This unique ability has baffled scientists for years.
Corey Allard, a cellular biologist at Harvard, expressed his amazement at the slug’s capability to steal and incorporate parts of other organisms into its own cells. This phenomenon is unlike anything seen in the animal kingdom.
In a recent study conducted by biologists at Harvard, the team delved deeper into the mechanisms behind the sea slug’s thievery. They discovered that the slug doesn’t digest the algae’s chloroplasts but diverts them into small sacs in its intestines. These sacs, termed ‘kleptosomes’, keep the chloroplasts alive and functional before they are transported to structures on the slug’s back.

The researchers also found that the stolen chloroplasts continued to function and even contained slug proteins. The color variations in lettuce sea slugs may be indicative of their health status, with well-fed slugs appearing green and those lacking food turning orange.
It appears that the sea slugs resort to digesting the chloroplasts only when necessary, possibly due to food scarcity or limitations in sustaining the alien chloroplasts. This symbiotic relationship between the slug and algae could have broader implications for understanding how organisms acquire new abilities through absorption.
By studying these unique creatures, scientists hope to uncover insights into long-term evolutionary processes, such as the origin of mitochondria in cells. The research on lettuce sea slugs was recently published in the journal Cell.