August 2019

By Ranger Amy

When B.A. Steinhagen Reservoir was drained this summer, most animals were able to retreat into the creeks and river channels, but not all. Sprawled across the dry lake bed were dead freshwater mussels. Their slow mobility led to their demise, but it gave us and biologists a chance to study them up close. Freshwater mussels often go unseen, but they are underwater treasures.

Freshwater mussels

After talking with TPWD biologist Adam Whisenant, I learned that there are 50 species of freshwater mussels native to Texas. His team counted 21 different species on Lake Steinhagen. This includes the rare Texas threatened species, the Texas Heelsplitter.

On the outside, mussels appear drab. Inside they’re covered in mother-of-pearl in iridescent white, blue and pink. None of the (thousands of) mussels surveyed by the biologists had any pearls, but they’re still treasures.

Cleaning the water

Mussels provide a valuable service to us and all lake life as underwater filters, filtering out muddy and polluted water throughout their lives. They do this so that they can filter feed on different plankton that float in the water.

Growing the next generation

They also have unique life cycles. To reproduce, males release their sperm into the water. It enters nearby females through their siphons.

Their babies, known as glochidia, can’t swim free into the water, but need a host fish. The female makes a “lure” to attract a passing fish. When the fish is within her grasp, she’ll clamp onto it and release her glochidia onto the fish.

Like tiny pack men, baby mussels clasp onto the fish’s gills and get nutrients from the fish. When they are ready to settle into life as a filter feeder, they detach, leaving the fish mostly unharmed.

Support the mussels!

We are lucky to live in a state where so many freshwater mussels work to keep our waterways clean and beautiful. It’s up to us as citizens to do our part to protect these underwater treasures.

Knowing they’re here and that they’re beneficial helps, so please tell others. Be aware of changes in our waterways that might impact them. Be the eyes and ears for our Texas treasures. Their future is in our capable hands.