The term 'endangered species' often brings up images of gorillas in the Congo or the tiger roaming the jungle.

However, there are numerous endangered species found locally in Tennessee. According to tables recorded by the Tennessee Department of Environment and Conservation, there are many endangered species in Tennessee, many of which are endemic to the region.

One of these is the oyster mussel. According to the International Union for Conservation of Nature (IUCN), which regularly publishes data on all known species of life, the oyster mussel has seen an 80% drop in its population.

In the 25 years since the species was first listed by the IUCN as being vulnerable, the oyster mussel's has become so grave that it seems likely to die out unless serious work is done to restore its habitat.

The IUCN says that the biggest threat to the oyster mussel's existence is the creation of dams throughout its natural habitat, which extends from Kentucky, through Tennessee and down to Alabama.

According to the U.S. Fish and Wildlife Services, pollution and the zebra mussel, a non-native species of freshwater mussel accidently introduced by ships travelling from Europe, also pose serious threats for the survival of freshwater mussels in general.

One of the key ways in which freshwater mussels benefit everyone else is that they filter the water, which they live in. Also, they provide one of the main sources of food for otters and muskrats, according to the U.S. Fish and Wildlife Services. In addition to this, almost all artificial pearls are created using freshwater mussels like those found in Tennessee rivers.