Freshwater mussels: Ancient inhabitants of Indiana’s rivers
By Tom Swinford, Land Preservation Director
Land Preservation Director Tom Swinford and Indiana DNR’s Brant Fisher look for mussels in Beanblossom Creek. Photo by Chris Fox
Parking our trucks at the edge of a recent tree planting, staff from Sycamore Land Trust and the Indiana DNR Division of Fish & Wildlife walked through tall late-summer vegetation toward the sycamore trees ahead—reliable signposts of the stream below.
Standing beneath their broad canopies, we looked down steep banks to the water: Beanblossom Creek, flowing quietly through a series of short riffles and winding around weathered logs and scattered branches. The creek was seasonally low—exposed and calm—ideal conditions for surveying the streambed for freshwater mussels.
It was here, in this ordinary-looking stretch of creek, that years of protected land and patient restoration would reveal themselves in an unexpected way.
We stepped into the stream and focused our gaze on the gravel and mud. Almost immediately, we saw them—the angular brown knobs of living mussel shells scattered across the bottom, and many of them. Excitement crept into our voices at the quiet reward of finding a healthy mussel bed where so many streams have lost them. Indiana historically supported about 80 freshwater mussel species, roughly half of which are now extirpated or listed as endangered at the state or federal level.
Mussels found at Beanblossom Creek during a 2025 mussel survey. Photo by Chris Fox
Freshwater mussels—technically Unionids (yoo-nee-ON-ids)—are among the most remarkable forms of aquatic life. Unlike marine mussels, they lack the fibers that anchor their saltwater relatives to rocks and pilings. Instead, these freshwater mollusks live free within the gravel and sediment of creeks and rivers, moving slowly with the help of a single powerful muscular “foot.”
Their reproduction is equally fascinating. Female mussels store eggs in their gills, where males fertilize them. The developing larvae, called glochidia (glo-KID-ee-a), possess tiny hook-like structures that must attach to a host fish to survive. When a curious fish approaches, the female releases a jet of glochidia through her siphon; the larvae latch onto the fish’s gills. This temporary parasitic phase allows mussels to disperse throughout a watershed before dropping off to establish new beds and mix genetically with other populations.
Though they may seem simple or sedentary, mussels are highly evolved animals—mollusks and relatives of snails, squid, and octopus. North America’s freshwater mussels have adapted to habitats ranging from small creeks to large rivers. As long-lived filter feeders, they are vulnerable to everything that flows through their patch of habitat, making them powerful indicators of ecosystem health. Where mussels thrive, water quality and habitat stability have persisted over time. For this reason, Indiana DNR’s Nongame Fish & Wildlife Program has invested heavily in mapping and conserving their distributions statewide.
Stream mussels do not survive on hope alone. As animals that can live for decades, they reflect the long-term stability and health of their underwater environment. By protecting and restoring intact ecosystems—forests, wetlands, springs, and floodplains—we create the conditions that sustain the most vulnerable plants and animals. Mussels are here because this landscape continues to support them.
Mussels also have a long and meaningful relationship with people. Their lustrous nacre has been prized for millennia. Indigenous peoples crafted shells into beads and ornaments and relied on mussels as a food source, leaving behind shell middens along rivers like the White. Later, in the late 1800s and early 1900s, the region’s great mussel beds supported a booming pearl-button industry, with factories along the Ohio, Wabash, and White Rivers. Before the advent of plastics, mussel shell was a primary source of buttons—an industry that employed thousands but ultimately led to overharvest and the need for modern conservation measures.
A button mussel found in the White River. Photo by Tom Swinford.
Beanblossom Creek is an Indiana stream not unlike many others, glimpsed from old roads winding beneath a canopy of trees and past family farms. Yet in this seemingly unassuming creek, conservation of rare and endangered species is happening quietly every day. Protecting a connected natural landscape requires patience and a steady hand on the wheel. Today’s work ensures a future where remarkable life continues to persist—in community, and over time.
This story was featured in the Winter – Spring 2026 issue of The Twig, “The Water Quality Issue.” Read more at sycamorelandtrust.org/twig.
