Mustang Island is a coastal barrier island with a unique and complicated ecosystem, dependent upon sand dunes. Coastal dunes are the product of wind-deposited sand anchored by sparse mats of vegetation. The height of well-vegetated dunes may reach 35 feet, though 15-20 feet is average. The dunes are capable of reducing the destructive might of hurricane-driven waves and protecting bay and mainland areas. In some areas, inland and bayside dunes occur, which are generally smaller but spread over larger areas than the primary beach-side dunes. The vegetation holding the dunes in place is drought-resistant species such as sea oats, beach panic grass, and soilbind morning glory.