Sorex palustris, also known as the marsh shrew, is a species of small, semi-aquatic mammal found in wetlands throughout North America. It is commonly referred to as the water shrew or marshrew due to its affinity for water and moist habitats. Other synonyms for Sorex palustris include the bog shrew, marsh shrew mole, and fen shrew. Despite its small size, the marsh shrew is an important component of wetland ecosystems, preying on insects, small fish, and amphibians. Its unique physical adaptations allow it to move swiftly through water and burrow through soft soils. However, habitat loss and degradation pose threats to the survival of this species and its ecological role in wetlands.