The Headless Sea Slug

In a process known as autotomy, two species (Elysia c.f. marginata and Elysia atroviridis) of photosynthetic sea slugs known as sacoglossans are able to remove their heads from their bodies. Once the head is detached, a fully regrown body with all of its internal organs will grow from the detached head in about 3 weeks. With its heart still beating, the discarded, original body remains reactive and can live up to a few days to a few months without ever regrowing a new head. Like other sacoglossans, E. marginata and E. atroviridis steal chloroplasts from their algal food allowing them to photosynthesize. Photosynthesis may play a key role in their ability to survive with just a head for so long and facilitate the regeneration of an entire new body! But why do they do this? Is it just a fun way to creep out its friends? The leading hypothesis suggests that the animal may shed its body in order to get rid of pesky parasites! Not a bad strategy! Heck, I might shed my body off after all the Halloween candy I'm going to eat and avoid the tummy ache lol.

(Note: Artistic liberties were taken to draw the deep sea creatures so they aren’t all to scale. Some of them, like the vampire “squid” are actually quite small and not as big as a goblin shark just FYI)

Based on the research Sayaka Mitoh and Yoichi Yusa