Mussels (Bivalvia, family Unionidae) known from the Little River. This is an incomplete list as some specimens are still being identified.
| Actinonaias ligamentina | mucket |
| Amblema plicata | threeridge |
| Arkansia wheeleri | Ouachita rock pocketbook |
| Ellipsaria lineolata | butterfly |
| Elliptio dilatata | spike |
| Fusconaia flava | Wabash pigtoe |
| Lampsilis cardium | plain pocketbook |
| Lampsilis satura | sandbank pocketbook |
| Lampsilis siliquoidea | fatmucket |
| Lampsilis teres | yellow sandshell |
| Lasmigona complanata | white heelsplitter |
| Lasmigona costata | flutedshell |
| Leptodea fragilis | fragile papershell |
| Ligumia subrostrata | pondmussel |
| Megalonaias nervosa | washboard |
| Obliquaria reflexa | threehorn wartyback |
| Plectomerus dombeyanus | bankclimber |
| Pleurobema rubrum | pyramid pigtoe |
| Pleurobema sintoxia | round pigtoe |
| Potamilus purpuratus | bleufer |
| Ptychobranchus occidentalis | Ouachita kidneyshell |
| Pyganodon grandis | giant floater |
| Quadrula apiculata | southern mapleleaf |
| Quadrula cylindrica | rabbitsfoot |
| Quadrula nodulata | wartyback |
| Quadrula pustulosa | pimpleback |
| Quadrula quadrula | mapleleaf |
| Strophitus undulatus | creeper |
| Toxolasma parvus | lilliput |
| Toxolasma texasensis | Texas lilliput |
| Tritogonia verrucosa | pistolgrip |
| Truncilla donaciformis | fawnsfoot |
| Truncilla truncata | deertoe |
| Utterbackia imbecillis | paper pondshell |
| Villosa arkanasasensis | Ouachita creekshell |
| Villosa iris | rainbow |
| Villosa lienosa | little spectaclecase |