Starfish apparently really like their privacy. Two biology students in Denmark learned this the hard way. They’d been given a relatively simple assignment; label starfish with tiny tags that would let researchers identify individual animals for future studies. So they injected small tags (like the microchips used to identify pets) into the starfish, only to find the tags outside of the starfish a few days later.
When they looked into the mystery, they found that the starfish were ejecting the tags through the end of their arms. The tag would travel around inside the starfish, avoiding all organs, and then get forced out of the starfish’s arm without wounding the animal. That would be like a human getting shot in the leg and then ejecting the bullet from their fingers without any internal injuries. The research is described in a new paper published in The Biological Bulletin.
The researchers still aren’t sure how the starfish manage the feat. It doesn’t appear to be related to their digestive system which is kind of terrifying on its own. One thing is clear … they’re going to need a different way to tell starfish apart.
Watch the biology students talk about their discovery (and a possible low-tech solution!) below: