Louisiana pearlshell facts for kids
Quick facts for kids Louisiana pearlshell |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Margaritifera
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| Species: |
hembeli
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The Louisiana pearlshell, also known as Margaritifera hembeli, is a very rare type of freshwater mussel. It's a bivalve mollusk, which means it has two shells that open and close, like a clam. This special mussel lives in small streams in Louisiana, USA. It used to live in Arkansas too, but it's gone from there now.
The Louisiana pearlshell can grow to about 10 cm (4 in) long. It lives on the sandy or gravel bottoms of streams where the water flows quickly. Its life cycle is quite interesting because it includes a stage where it lives inside a fish for a short time. This mussel is very sensitive to changes in its home, like too much dirt in the water. Because it's so rare and its numbers are shrinking, the International Union for the Conservation of Nature has listed it as "critically endangered". This means it's at a very high risk of disappearing forever.
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What Does It Look Like?
This mussel can grow to be about 10 centimeters (about 4 inches) long. That's roughly the length of a smartphone! It's also about 5 centimeters (2 inches) wide and 3 centimeters (1 inch) tall.
The outside of the Louisiana pearlshell is usually dark brown or black. If you could look inside, you would see a beautiful shiny white layer called nacre. This is the same material that pearls are made of!
Where Does It Live?
Its Stream Home
The Louisiana pearlshell lives in small, shallow creeks. These creeks usually have clear water and bottoms made of sand or gravel. You'll often find these mussels in areas called riffles. Riffles are parts of a stream where the water flows faster and is a bit bumpy, rather than in calm, still pools. The ground where they live needs to be stable, meaning it doesn't shift around a lot.
Life Cycle of the Pearlshell
How Mussels Grow
Like many other freshwater mussels, the Louisiana pearlshell has a unique way of growing up. The adult mussels release their tiny babies, called glochidia, into the water. These glochidia are like tiny larvae.
A Ride on a Fish
Once in the water, these tiny glochidia need to find a fish. They attach themselves to the fish's body, often on its gills or fins. They live there as parasites for a short time. This doesn't usually hurt the fish much. During this time, the glochidia grow and change into tiny juvenile mussels.
Some of the fish species that help the Louisiana pearlshell grow include the Striped shiner (Luxilus chrysocephalus), the Redfin shiner (Lythrurus umbratilis), the Golden shiner (Notemigonus crysoleucas), and the brown madtom (Noturus phaeus). After they have grown enough, the young mussels drop off the fish and settle onto the stream bottom. There, they continue to grow into adult mussels.
Why Is It Endangered?
A Shrinking Population
When the Louisiana pearlshell was first put on the Endangered Species List in 1988, scientists thought it only lived in the Bayou Boeuf river system in Rapides Parish, Louisiana. Most of the mussels were found in just a few streams there.
Later, in 1993, more groups of these mussels were found in other streams in Grant Parish, Louisiana. Because more mussels were discovered, its status was changed from "endangered" to "threatened." However, it's still in danger. It used to live in Arkansas, but it has completely disappeared from all the waterways there.
Threats to Its Home
The biggest danger to the Louisiana pearlshell is the loss and damage to its habitat. Here are some of the main problems:
- Dams: Building dams on waterways, and even beaver dams, can change how the water flows. Mussels need fast-flowing, clear water.
- Sedimentation: This means too much dirt and mud gets into the streams. Activities like cutting down trees (called silviculture), maintaining roads, and livestock grazing nearby can cause more dirt to wash into the water. Gravel mining can also add more sediment. The mussels can't live well when their stream beds are covered in mud.
- Low Genetic Variety: Scientists have looked at the mussel's genes. They found that the species has low genetic variability. This means there isn't much difference in the genes between individual mussels. When a species has low genetic variety, it can be harder for them to adapt and survive when their environment changes.
Because the Louisiana pearlshell now lives in only two river systems in central Louisiana, and its numbers have dropped by more than 80% in recent decades, it is now considered "critically endangered" by the International Union for the Conservation of Nature. This means it needs a lot of help to survive.
