Dauphin Island is a 17-mile long, 3/4-mile wide barrier island that is parallel to the coastline. Once formed, barrier islands are not static; they are dynamic systems with many variables influencing them. Size, shape and location are constantly changing due to waves and currents. The major function of a barrier island is to protect the mainland from the wind and wave energy associated with storms. Barrier Island habitats include sandy beaches, dune systems and maritime forests. Aquaria in this gallery include saltwater tanks and terrestrial aquaria. Saltwater tanks include animals such as: shrimp, clams and hermit crabs.