# Rock-pocketbook (*Arcidens confragosus*) The Rock-pocketbook is a special kind of clam that lives in rivers. It has a unique shell that looks like a little pocket, perfect for hiding away from predators. - **Category:** [Invertebrate](https://www.snappit.app/explore/categories/invertebrate) - **Rarity:** Common - **Danger:** 1/5 · Very low - **Habitat:** Freshwater rivers ![Rock-pocketbook](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Arcidens_confragosus.JPG&width=800) Photo: Byron hamstead, CC BY-SA 3.0 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Arcidens_confragosus.JPG) ## Appearance The Rock-pocketbook is a freshwater mussel with a thick, oval to squarish shell, often tan to dark brown. Its surface is rough, covered with noticeable bumps and wrinkles, giving it a 'rocky' appearance. The inside of the shell is typically a pearly white color. ## Taxonomy - **Kingdom:** Animalia - **Phylum:** Mollusca - **Class:** Bivalvia - **Order:** Unionida - **Family:** Unionidae - **Genus:** Arcidens ## Interesting facts - Baby Rock-pocketbooks must attach to a fish's gills or fins to grow! - Rock-pocketbooks breathe underwater by using feathery gills hidden inside their shells! - They use a powerful, muscular "foot" to slowly crawl and bury themselves in the mud! - This mussel can close its shell super tight and survive for weeks without eating! ## Special abilities - **Water Purifier:** Rock-pocketbook can filter tiny food particles and pollutants from water because of specialized gills, which helps keep rivers clean. - **Riverbed Anchor:** Rock-pocketbook has a strong muscular foot that helps them burrow into riverbeds for stability and protection from strong currents. - **Lure Master:** Rock-pocketbook can wiggle a fleshy flap on their shell that looks like a tiny fish, attracting real fish to help spread their babies. ## Measurements & details - **Size:** 70-150 mm - **Lifespan:** 3650-7300 days ## Diet & Feeding These mussels filter tiny food particles and algae from the water using special gills. - **Primary Foods:** Algae, Detritus, Bacteria, Microscopic plankton - **Foraging Method:** Filter feeding ## Ecological connections - **Eaten by:** [Raccoon](https://www.snappit.app/explore/raccoon) (*Procyon lotor*) — Raccoons often eat these mussels. - **Eaten by:** [Muskrat](https://www.snappit.app/explore/muskrat) (*Ondatra zibethicus*) — Muskrats dig up mussels from riverbeds. - **Depends on:** [White Crappie](https://www.snappit.app/explore/white-crappie) (*Pomoxis annularis*) — Young mussels briefly attach to their gills for development. - **Depends on:** [Largemouth Bass](https://www.snappit.app/explore/largemouth-bass) (*Micropterus salmoides*) — Larval mussels attach to these fish to spread. ## Traits - [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring. - [Colorful](https://www.snappit.app/explore/traits/colorful): Colorful describes organisms or objects displaying a wide range of bright and distinct colors. - [Filter Feeder](https://www.snappit.app/explore/traits/filter-feeder): Filter feeders obtain nutrients by straining suspended food particles and small organisms from water. - [Herbivorous](https://www.snappit.app/explore/traits/herbivorous): This trait characterizes organisms whose diet consists entirely or primarily of plant material. - [Longevous](https://www.snappit.app/explore/traits/longevous): This trait characterizes organisms with an exceptionally long lifespan compared to others of their kind. - [Freshwater](https://www.snappit.app/explore/traits/freshwater): Freshwater habitats include non-saline aquatic environments such as rivers, lakes, ponds, and wetlands, vital for numerous species. - [Keystone Species](https://www.snappit.app/explore/traits/keystone-species): Describes a species whose presence and role have a disproportionately large effect on its environment. - [Endangered](https://www.snappit.app/explore/traits/endangered): Endangered status indicates a species is at a very high risk of extinction in the wild in the near future. ## Collections - [Insects](https://www.snappit.app/explore/collections/insects) ## Safety **Danger:** 1/5 · Very low Be careful near water and always have an adult with you. ## Frequently Asked Questions ### How to identify Rock-pocketbook? Compare body symmetry, shells, segments, legs, tentacles and how the animal moves. Invertebrates span many unrelated groups, so start with body structure. Invertebrate Identifier: upload a photo and compare the visible details. ### How big is Rock-pocketbook? 70-150 mm ### How long does Rock-pocketbook live? 3650-7300 days ### What does Rock-pocketbook eat? These mussels filter tiny food particles and algae from the water using special gills. ### Where is Rock-pocketbook usually found? Freshwater rivers ### How does Rock-pocketbook hunt? Filter feeding ## More Invertebrate - [Coral](https://www.snappit.app/explore/coral) - [Crab Spider](https://www.snappit.app/explore/crab-spider) (*Mecaphesa asperata*) - [Garden Spider](https://www.snappit.app/explore/garden-spider) (*Araneus diadematus*) - [Brown Recluse Spider](https://www.snappit.app/explore/brown-recluse-spider) (*Loxosceles reclusa*) --- Source: [Rock-pocketbook: Facts & Places to See — Snappit](https://www.snappit.app/explore/rock-pocketbook)