This sounds fake.
These sea slugs sever their own heads—and grow whole new bodies in under a month
They drop the heart with the rest and start over, as if bodies were optional.
The part that checks out ↘
It really happened.
In 2021, biologists watched two Elysia sea slugs deliberately shed their bodies and crawl on as free heads. Each head rebuilt a heart and all missing parts in about three weeks, finishing within a month. The trick seems tied to stolen chloroplasts in their tissues, which can photosynthesise and may feed the head during regrowth. The behavior was voluntary: a gentle loop at the neck triggered it; fake predator pinches did not.
It recasts the body as replaceable hardware and the head as the essential unit. It also hints that borrowed plant parts can bridge an animal through an extreme repair job.
No folklore. Actual sources.
- 1 Extreme autotomy and whole-body regeneration in photosynthetic sea slugs
Primary data: species, sample sizes, regeneration timeline (~20 days; ≤28 days), voluntary autotomy methods (nylon thread), and kleptoplasty hypothesis.
vliz.be
- 2 Extreme autotomy and whole-body regeneration in photosynthetic sea slugs - PubMed record
Bibliographic details (authors, journal, date, DOI) and abstract stating autotomy, regeneration, and proposed role of kleptoplasty.
pubmed.ncbi.nlm.nih.gov
- 3 Now that’s using your head: a sea slug’s severed noggin sprouts a new body
Independent summary noting a new body can form in about three weeks and identifying Elysia cf. marginata.
nature.com
- 4 This Sea Slug Can Chop Off Its Head and Grow an Entire New Body—Twice
Corroborates species (Elysia cf. marginata, E. atroviridis), ~three‑week regeneration, and kleptoplasty as the proposed energy source.
scientificamerican.com