Its advantage is that, besides grasping things tightly, it can also squeeze into nooks and crannies that are inaccessible to vertebrate arms of similar dimensions.
So far it has not been detected in a vertebrate animal.
A dog is a vertebrate animal.
A vertebrate amphibian.
A functionally similar bone in the leg or hind limb of a vertebrate animal.
The spleen of certain vertebrate animals, such as cows or pigs.
This is the first time in a vertebrate animal that you can show such a clear connection between an animal's behavior and the changes at the molecular level.