In order to better understand animals, researchers frequently tag them with microchips. Unfortunately for scientists, starfish just aren't having it.
Two biology students at the University of Southern Denmark recently discovered that starfish have the incredible ability to squeeze foreign objects between their organs and back out of their bodies.
Frederik Ekholm Gaardsted Christensen and Trine Bottos Olsen inadvertently discovered this after successfully injecting microchips into a group of starfish and then finding the tags at the bottom of the tank days later.
After closer observation, Christensen and Olsen realized that the starfish were squeezing the microchips out through the skin on the tips of their arms.
"Every time we put a tag into a starfish, they rid themselves of the tag within a few days. It came out directly through the skin," the students explained in a university news release. "The starfish simply pushed it out through the skin at the end of one arm and then went on as if nothing had happened."
To track where the microchips were traveling, the students injected 20 starfish with magnets. They then dangled other magnets over the body of each starfish, using the makeshift pendulum to trace the first magnet's path.
Surprisingly, the starfish ejected the foreign objects through the tip of an arm instead of pushing it out through the hole created during the injection.
According to the Scientific American, the students' magnets seemed to travel randomly through a starfish's body, sometimes moving back and forth, before being expelled.
The starfish managed to push the microchip between its organs without harming itself, the students explained, though they do not know how or why this happens.
According to the university, this is the first time researchers have observed a starfish expelling foreign objects through its skin.
"It's probably not very pleasant to have foreign objects inside oneself," Olsen says in the video.
Christensen and Olsen's findings were published in the Biological Bulletin in April.