Gobiifromes

Gobiiformes is an order of fish containing about 210 genera and 1700 species. Gobies are marine fish which occasionally wander into adjacent freshwater areas. Their pelvic and medial fins unite and form a sucker, which they may use to adhere to objects such as plants and rocks. Some sand dwelling gobies have a symbiotic relationship with shrimp. The shrimp will dig a burrow in the soft sand substrate in which the two organisms live. The goby will then alert the shrimp to danger and they will both burrow deeper. There are also reef dwelling gobies. Some species of reef dwelling gobies exhibit a bidirectional sex change. Generally these go from female to male (protogynus), though under lab conditions the opposite direction has been induced by removing the female. When this occurs the largest male will become a female. If two males are ever placed in the same area, one will change to form a matching pair of male and female. Of course this may only work in lab conditions as in the wild, the gobies will likely simply migrate to a new area.