Evolution works.
We have blue belly lizards here and they have the tail shedding capability as well. I’ve seen a few with regrown tails and they are not a nice as the original – shorter and less tapered. Perhaps I was seeing one not yet completely grown out, though.
Usually regrown tails are shorter than the original. They lack bones and are just made up of tissue.
Ha!!!
More evidence the decapitations were not spontaneous: they mention in the article that “the researchers found that only the younger slugs are capable of autonomy and regeneration. When older slugs had their heads removed, the heads survived for up to 10 days but they never started eating and did not start to regenerate before dying.”
Older slugs could not do this trick, presumably would instinctively know not attempt it, and in any case the slugs “had their heads removed”.
As an undergrad I worked in a neurophysiology lab recording electrical signals from the photo-receptors (“eyes”) of Hermissenda crassicornis a marine nudibranch. It was amazing that we could remove the head, use a protease enzyme to clean away connective tissue, then work on the living, exposed brain for hours.