The most interesting example is the fish commonly known as ogrefish. It can be found in five of the seven seas and, at first glance, it is one species. However, even though they share a common ancestor, allopatric speciation caused the original species to split in five. This, while important, is not the interesting bit. All modern ogrefish have one appendage used to disturb the sand at the bottom of the shallow waters where it lives, forcing the small animals from which it feeds to leave their shelters. The interesting part? The original species had no such appendage.
Bulsara, F., May, B., Deacon, J., Taylor, R. (1974). Convergent Evolution in Seven Landlocked Water Bodies. Journal of the Marine Biological Association of the United Kingdom, 54(3), 741-758.
















