The impossible claim
This animal digests its own brain. After settling on a rock, the sea squirt absorbs its own tail and much of its nervous system — and never moves again.
The verified facts
The sea squirt starts life as a tadpole-like larva with a small brain (cerebral ganglion), a notochord, and a tail for swimming — surprisingly vertebrate-like features for an animal whose adult form is a barrel anchored to a rock. Once it finds a suitable surface, it attaches head-first and undergoes one of the most radical metamorphoses in the animal kingdom:
- Its tail is reabsorbed and digested as fuel for the transformation
- Most of its nervous system, including its cerebral ganglion (the brain), is broken down and recycled
- The freed building blocks are reassembled into its adult body: a filter-feeding barrel with two siphons — one drawing water in, one expelling it
- Its closest living relatives are not other stationary sea creatures, but vertebrates — we share a common ancestor with it
- This self-brain-lobotomy inspired the phrase “eating one’s own brain” in neurobiology literature about regression of nervous systems
Watch
🎬 This Animal Eats Its Own Brain — on YouTube — Episode 25
Sources
- Nakamura, M. J. et al. (2019). Ciona intestinalis metamorphosis and neural regression. Developmental Biology.
- Manni, L., et al. (2004). Nervous system regression in Ciona. Journal of Experimental Zoology.
- Delsuc, F., et al. (2006). Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature.
Part of Impossible Creatures — every fact verified, every creature real. Watch the Shorts at youtube.com/@taginbertcom.