The southern brook lamprey (Ichthyomyzon gagei) is a lamprey found in the Southern United States including Arkansas, Louisiana, Mississippi, Alabama, and Georgia. It is a jawless fish with a sucking mouth on one end of it (like a leech). It can appear to be a small eel, since it is rarely longer than one foot in length. Geographic distribution The southern brook lamprey occurs in slow moving rivers and streams from Florida to southern Mississippi, Georgia, and Arkansas along the Gulf Coast west to Oklahoma and Texas. It ranges as far north as Minnesota and Wisconsin, and has been reported to occur in the Chattahoochee river system and the Conecuh River system in Alabama, the Sabine river system in Texas and Louisiana, the Illinois river system in Oklahoma, and the Neches River system in Texas. The southern brook lamprey was thought to be restricted to the southern United States; however, Becker observed southern brook lamprey in Wisconsin in 1983. The southern brook lamprey has also been reported to occur as far north as the Spruce river and the Tamarac river in Wisconsin and Minnesota. Unpublished findings have also shown that the southern brook lamprey inhabits tributaries of Choctawhatchee Bay and the Ochlockonee River system in Florida, the Chattahoochee river system in Georgia, and the Trinity and San Jacinto river systems in Texas. Ecology The diet of the southern brook lamprey changes as it undergoes metamorphosis during its life cycle from one phase to the next. The diet of larval southern brook lamprey consists mainly of organic detritus. Studies that focused on closely related lamprey species (I. fossor) found that the guts of larval lampreys contained 97.9% organic detritus, 2.12% algae, and 0.09% bacteria. After metamorphosis into the adult phase, southern brook lampreys do not feed but rely on stored fat reserves accumulated during the larval stage for energy and nutrients. Studies have found that the digestive tract of the lamprey actually shrinks and becomes functionally useless as larval lampreys enter the adult stage. The southern brook lamprey encounters a wide range of predators in its natural habitat. The eggs of adults are preyed on by various species of fish and crayfish. Southern brook lampreys in the larval stage serve as prey for a wide range of fish and bird species. Adult forms are preyed upon by larger fish species such as the Northern pike (E. lucius), perch species, the European