Why Pearl Mussels need our help
An educational resource created by the Pearl Mussel Project
Do you know what these are?
These animals are called Freshwater Pearl Mussels. They live on the river bed in rivers and streams with very clean water and you can find them in some lakes too.
Freshwater Pearl Mussels can live to be over 120 years old! That makes them one of Ireland's longest living animals.
Unfortunately the Freshwater Pearl Mussel is critically endangered. That means that there are very few Pearl Mussels left in the world and we need to try and protect them.
In Ireland we are very lucky because we have some of the highest numbers of Pearl Mussels in Europe. There are eight special places in Ireland that have the best populations of Pearl Mussels in Ireland. The Pearl Mussel Project is working with farmers in these places to help to protect the Pearl Mussel.
Have a look at these eight areas on this map. They have a red line around them. Do you live in one of these areas? Which area is closest to you?
Map showing Pearl Mussel Project catchments and associated waterbodies
What kind of animal is a Freshwater Pearl Mussel?
All of the animals in the world can be put into different groups. Freshwater Pearl Mussels have no back bone (spine) so that means that they belong to a group called invertebrates. Humans have backbones so we belong to a different group called vertebrates.
Can you think of other examples of vertebrates and invertebrates?
There are lots of different types of invertebrates so we can divide them up into more groups.
Freshwater Pearl Mussels have a soft body protected by a hard shell. Invertebrates that have a hard shell on the outside like this are called molluscs.
The Freshwater Pearl Mussel doesn't live inside one shell like a snail does, it actually has two shells like a clam.
Just like a bicycle has two wheels, we use the word bivalve for animals with two shells. So if someone asks you what kind of animal the Freshwater Pearl Mussel is you can say that it is a bivalve mollusc!
Why are Freshwater Pearl Mussels important?
Good question! Freshwater Pearl Mussels only live in very clean water, so if there are Pearl Mussels in a river or stream we know that the water is very clean and that the river is healthy. This is good for all of the animals living in the river, but its also good for us humans, because we rely on rivers, streams and lakes for lots of different things.....Can you think of some of them?
What habitat does the Freshwater Pearl Mussel live in?
A habitat is a place where an animal or plant lives and grows. We already know that Freshwater Pearl Mussels can live in rivers and streams, and that they like very clean water - but there are some other things that the Pearl Mussel needs to be able to survive.
Adult Pearl Mussels live with the bottom of their shells buried in the river bed, so it is important that the river bed is made up of a nice mixture of small and medium sized stones to help keep the mussel in place.
It is also important that the water does not flow too fast (they could get washed away!) or too slow (if the river moves too slow it might not have enough oxygen for the mussels).
So Freshwater Pearl Mussels live in rivers or streams with very clean water, that doesn't flow too fast or too slow, and have a good mixture of stones and gravel on the river bed to help keep the mussels in place.
How does a Freshwater Pearl Mussel find the right habitat?
Not all Pearl Mussels find the right habitat - and only the ones that end up in the right place will survive to become adult mussels. The story of how a Pearl Mussel ends up on the river bed is amazing - it even needs the help of a fish!
Adult female Pearl Mussels protect their eggs inside their shells until they are ready to be released into the water.
One female mussel can release up to 4 million baby mussels into the water over a summer - but all of these will not survive to become adults.
These little mussels are called glochidia and they look exactly like the adult mussels, just much smaller. These glochidia float in the water with their shells open.
Now, the next part of the story is very important.
To survive to the next stage the glochidia have to grab onto a salmon or a trout, but this does not always happen.
For those lucky few glochidia that are near a salmon or trout at the right time, they snap their shells shut on the gills of the fish and hang on here for 9 months.
Can you spot the snapping glochidia in this video?
The glochidia go everywhere the fish goes for the next 9 months. They grow and develop while they are attached to the fish gills, but they do not hurt the fish.
Where ever the fish is when the mussel is big enough to drop off is the place that the mussel will spend the rest of its life.
It will only be able to survive here if it is the right habitat. Do you remember what kind of place that would be?
The young mussel stays buried in the river bed for 5 years.
It is very important that the river bed is clean and has lots of oxygen for the young mussel to grow into an adult.
When it is big enough it pushes itself up to the surface of the river bed, so that the top of its shell is in the water and it can feed.
When they are around 12 years old these mussels produce a whole new generation of glochidia and the cycle starts again!
When they are around 12 years old these mussels produce a whole new generation of glochidia and the cycle starts again!
Do Freshwater Pearl Mussels do anything?
Freshwater Pearl Mussels stay in the same place for almost their entire life!! It might sound very boring to us, but while they are buried in the river bed they are doing something very, very important - they are cleaning the water!!!
Do you see the two openings that each mussel has in the photograph? Imagine that each of those openings is the top of a straw. The pearl mussel sucks in water through one straw, filters out some of the things floating in the water for food, and squirts the rest of the water back out into the river through the other straw.
Animals that feed like this are called filter feeders - do you know any other animals that are filter feeders?
Just one Pearl Mussel can filter 50 litres of water in one day - that's almost a whole bath tub full of water!!!
Why are Freshwater Pearl Mussels endangered?
Well, Freshwater Pearl Mussels need very clean water to survive. At the moment most of our rivers and streams are not clean enough for the mussels to be able to live there. If there is too little oxygen, and too much nutrients and other pollutants in the river the mussels will die.
Do you remember the young mussels dropping off the gills of the fish? Unfortunately, the river bed is not clean enough in many places and this means that when young mussels drop off the salmon or trout they cannot survive where they land.
In a healthy population you would get lots of mussels of different ages, but at the moment we have mostly adult mussels in Ireland. Without young mussels, eventually the Pearl Mussel could become extinct.
Can you think of some reasons our rivers and streams are not clean? What can we do to try and stop this?
What is the Pearl Mussel Project?
At the Pearl Mussel Project we work with farmers to help them to protect Pearl Mussels by helping to improve the habitats on farms and the streams that flow into rivers where the mussels live.
We look at the different habitats on the farm and the different plants that grow there to see how environmentally friendly the farm is.
We also look at the rivers and streams on the farm to see if they are clean and healthy.
Using scorecards we give all of the fields on a farms a score out of 10. Fields that get 10/10 are the best for the environment and for Pearl Mussels and we hope that when our project finishes lots of our farmers will be getting high scores on their farms, which will benefit Pearl Mussels.
What can I do to help?
Well there are lots of things you can do. Maybe you can tell someone who does not know about the Freshwater Pearl Mussel a little bit about them and why it is important to protect them.
You could think of ways to keep our rivers and streams clean and make sure that you and your family do those things.
You could try to increase the biodiversity in your garden or local area. Why not try out our scorecard for gardens and see what score you get. Maybe you can think of some ideas to make your garden more environmentally friendly.
You can find the scorecard and some other activities, like a quiz and a word search, and watch some great videos about Pearl Mussels on our website !
The Pearl Mussel Project is an EIP (European Innovation Partnership) Locally Led Scheme being administered by Pearl Mussel Project Ltd. The Project is funded by the Dept. of Agriculture, Food and the Marine as part of Ireland's Rural Development Programme 2014-2020.
