An endemic organism is one that is found only within a certain region. There is a rush that goes along with seeing a species that can be found nowhere else. Georgia is actually home to a handful of endemic species, most of which are aquatic. The Altamaha Spinymussel (Elliptio spinosa) is a freshwater mussel only found in 3 river systems in Georgia. Freshwater mussels are actually the most imperiled group of organisms in North America. There are a large number of reasons why this could be but one thing is for sure, mussels are dying in large numbers. To give you an idea of how rare some species can be, when I worked in a mussel lab we would actually pit tag some species so that we would be able to find them later. In the time span of less than a year, our most productive mussel bed had completely died. For the Altamaha spinymuseel, it is estimated that populations have declined 50-70 percent and it only occurred in 7 sites out of 120 sites that were sampled after 2000. Few juveniles or small individuals were found in these surveys. It used to be found in the Ohoopee River system and Oconee River in addition to the Altamaha River system. In the Ohoopee and Oconee, the mussel is thought to be extirpated or populations are so small it is undetectable. All freshwater mussels, expect the Salamander mussel (Simpsonaias ambigua), have a stage in their life-cycle in which they are fish parasites. The glochidia, or baby mussels, attach to fish gills and develop there until they become juveniles. This is how they expand their range.
The Etowah darter (Etheostoma etowahae) is another species that is only found in the Peachtree state. It is a small fish that is about 2 inches long. The fish occurs a less than 10 locations in the Etowah River system. They prefer swift riffle habitats that have either cobble or gravel. There is likely less than 10,000 adults and at sites sampled the darter represents only a small part of the community. Because of this and the expansion of metro Atlanta into its habitat, the species is protected as an endangered species both federally and at the state level. They look very similar to the closely related greenbreast darter (Etheostoma jordani) and lipstick darter (Etheostoma chuckwachatte). Some scientists say that the Etowah darter and greenbreast darter differ by the red markings the Etowah darter has on its sides. This difference between species has been recently challenged with some saying you can’t tell the species apart without genetic testing. The Etowah darter does not co-occur with the lipstick darter so range maps can be used to determine which species you are looking at.
The Cherokee Darter (Etheostoma scotti) is also found in the Etowah River system. There isn’t that much known about the species. Biologists don’t even know what the total population size could be but known populations are small. It prefers small rivers and creeks that are 1 to 15 meters wide. The darter is intolerant of dams and moderate or heavy levels of silt. The females deposit only a single egg which could be a reason for their small population size. A study in 1995 stated that threats to the darter are numerous and only going to increase with the expansion of metro Atlanta. Most of the population occurs in Allatoona Reservoir. It is federally listed as a threatened species but The International Union for Conservation of Nature considers the darter to be endangered.
The Pigeon Mountain salamander (Plethodon petraeus) is only found on the eastern slope of the mountain in Walker and Chattago counties. They were 1st discovered in 1972 by a DNR employee. The 7-inch salamander prefers to live in the twilight zone of caves, areas where light still penetrates the cave. They are very rarely found away from caves. I have actually witnessed them in Petty Johns Cave on a trip with Georgia Girl Guides. At the sites that they are found, the salamanders are very abundant. However, because they are found in such few areas they are vulnerable. Most of the species habitat is in the Crockford-Pigeon Mountain Wildlife Management Area. There have been extensive surveys on nearby Lookout mountain but biologists haven’t found any populations there. They are similar to the slimy salamander (Plethodon glutinosus) but they differ in the way that their toes appear. The Pigeon Mountain salamander has special adaptations to its toes that allow it to cling to the walls of caves. The salamanders prefer to eat beetles and ants. During winter the salamanders are very hard to find but become active again in spring.
The Oconee Burrowing Crayfish (Cambarus truncatus) occurs in only a 228-kilometer square area, therefore, it is considered high endemic. Its current range is threatened by kaolinite mining activities, which could result in the species becoming endangered. For this reason, the crayfish are listed as threatened at the state level. As their name suggests the crayfish burrow, so they prefer sandy clay soils. In the soil, they create complex networks of tunnels. During the breeding season, the male will leave their tunnels in search of females. When a female releases eggs they attached to the swimmerets. When the juveniles hatch they are attached to the mother by a thread and remain this way until their second molt. It is rare to find more than one individuals in a burrow unless they are juveniles. The crayfish are pale to bright orange and are the only orange crayfish in the state of Georgia. Very little is known about their life history and genetic diversity of populations.
The most iconic of endemic species in Georgia is the Cumberland Island horse (Equus ferus caballus), while they are technically a subspecies. Cumberland Island is off the coast of Georgia and is only reachable by boat. The original horses were left on the island either in the 16th or 18th century. Today there are about 150 to 200 horses but these numbers have been documented to have a negative effect on the island. Many recommend that the herd size be reduced and genetic studies have shown this would not promote inbreeding. Currently, there is no management plan for the horses. This population is one of 7 horse herds on barrier islands off the United States. Due to disease and ingesting sand their lifespan is about half that of their ancestors.
Some sources list species that are also found in other Southeast states as Georgia endemics. These included the southern studfish (Fundulus stellifer), the goldline darter (Percina aurolineata), the sandbar shiner (Notropis scepticus), Apalachicola dusky salamander (Desmognathus apalachicolae), the Dougherty Plain cave crayfish (Cambarus cryptodytes), Ixodes affinis (a tick with no common name), Florida green watersnake (Nerodia floridana), southern Appalachian salamander (Plethodon teyahalee), and fat threeridge (Amblema neislerii).