Sea urchins do grown back their broken spines and I have proof. I’ve been watching it happen with my own eyes. The sea urchin in our fish tank was looking a bit frail this past month and then most of its spines just fell off. The spines on the bottom remained, so I was confused as to whether it was going to die or not.
It didn’t. Rather it has slowly been regrowing its spines. Other urchins we’ve raised have simply died when their spines fell off. Their bottom spines had also come off. From my observations, that would make it almost impossible for it move and gather food to eat. But, this urchin has kept its bottom spines. It’s been very active and eating well during this time. I have bags of dried seaweed from Gulf Shores that I’m feeding to it.
The spines are growing out of the base of the old spines. It resembles a starfish arm that you can see growing back. There’s the base and then a new “shoot” coming out of it at the end. It is really amazing and cool to watch.
It is really interesting to read about nature and science but it is really cool to see it in action.