Variation in armour of three-spine stickleback
bone | plate | evolution | stickleback | morph
The three-spine stickleback is an adaptable fish with variation in morphology and behaviour, inhabiting saltwater, brackish water and fresh water. It is armoured with 30-35 bone plates along its lateral line. In addition, it is equipped with three spines on its back and two pelvic spine. These features constitute an excellent anti-predator defence system. Yet, there is a strong selection for reduction in armour of three-spine stickleback in freshwater stickleback. In this project, the bone structure and lateral plate of 72 three-spine stickleback from salt, brackish and fresh water was compared. Three-dimensional description of bone structures was accomplished by the use of micro-computed tomography (µ-CT). The results reveal that three-spine sticklebacks in freshwater may not only reduced number of plates, but also decreased the size and thickness of the armour plates.