Natchitoches National Fish Hatchery
Southeast Region

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Freshwater Mussels

 

North America is home to nearly 300 species of freshwater mussels. Of those 300 species 70% are either extinct, endangered, threatened, or of special concern at either the state or federal level. Louisiana is home to 66 mussel species. The Louisiana pearlshell mussel is the only species that is only found just in the state of Louisiana.

 

Alligator Gar FishLarge LPM

Louisiana pearlshell mussels from Rapides Parrish, LA

 

 

Freshwater mussels have a unique life cycle. To understand a mussel's life cycle, think of butterflies. A butterfly hatches into a catapiler or larva that must undergo a metamorphosis. The larval form of a mussel is called a glochidia. The glochidia undergo their metamorphosis while attached to the gills or fins of a fish.

 

 

glochidia on fish gill

 

Glochidia or larval mussels attached to a gill fillament of a fish. See how the tissue of the gill grows around the glochidia to form a "cocoon".

 

 

Like the monarch butterfly who's caterpiller only lives on milkweed plants, certin mussels can only undergo their metamorphosis on certin fish. In order to ensure that their glochida attach to the proper fish, freshwater mussel have developed several different fishing techniques from lures, to nets, to even traping the fish in order to get their glochidia onto the desired fish host.

 

 

display of a mussels's fishing lure

Here is the fishing lure of the endagered Winged Mapleleaf Mussel.

 

 

Metamorphosed glochidia are called transformers. Once these transformers have completed their metamorphosis they break free from the fish and settle to the bottom of the river or lake and there they begin to grow. In a few months the transformers will go from microscopic to being large enough to see.

 

juvenile mussels

 

 

Quick links:

For more information about the mussel life cycle please check out the Unio Gallery

To find a mussel biologist in your area you and check out the Freshwater Mollusk Conservation Society

 

 
Last updated: July 10, 2020