Mobile Bay is an estuarine system that is an example of a drowned river valley. It encompasses 413 square miles, is approximately 31 miles long and has a maximum width of 24 miles at its southern end. Mobile Bay is a shallow estuary, averaging a depth of 10 feet and provides a transition between the fresh water wetlands of the Mobile-Tensaw Delta to the north and the marine environment of the Gulf of Mexico to the south.

Discharging 62,000 cubic feet of water per second, Mobile Bay is the fourth largest estuary in the United States. As an estuary, the major function of Mobile Bay is a nursery ground for many invertebrates and vertebrates. The aquaria in this gallery contain brackish water, a mixture of fresh and salt water, just like that found in Mobile Bay. The large Mobile Bay tank contains a replica of the legs of Middle Bay Lighthouse and a jetty. 

Manmade structures such as these provide a valuable habitat for many plants and animals. Other tanks depict habitats such as oyster reefs and salt marshes. Some exciting animals that your students may observe include: stone crabs, horseshoe crabs, blue crabs, oysters, spadefish, flounder...