The slugs, Elysia chlorotica,

Those genes are already there, in the slug, and transferred from generation to generation," Pierce told Canwest News Service on Monday. While survival by photosynthesis is a defining trait in the plant kingdom, "that's exactly what this slug does."

Noting that gene transfer between microscopic, unicellular organisms is known to occur, Pierce points out that "the most significant part of this is that genes have been transferred between two multicellular species. This is the first discovery of that happening."