Rhagor - Opening our national collections

The life of freshwater mussels

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Where do they live?

Mussels bury themselves in the sediment at the bottom of rivers and lakes. A small amount of the shell sticks out so the animal can stick its siphons into the water to feed.

A large foot sticks out the bottom of the shell and acts as an anchor. Some mussels rarely move more than a few metres in their lifetime (which can be up to 200 years in some species!)

Young mussels have to be completely buried when they are tiny because their feet are too small to anchor them properly. If the sediment is very dirty from pollution the baby mussels suffocate.

What do they eat?

Mussels suck in water, filter food particles then spit the water out. It is this action that cleans our rivers and lakes for us. However, if the water is very polluted the mussel will die from 'eating' too many chemicals.

A large adult mussel can filter 38 litres (8 gallons) of water a day!

Do they taste good?

NO! - Many freshwater mussels grow quite large and are therefore too chewy for us to enjoy eating.

YES! - Many animals such as otters and racoons would disagree! They crack open the shells and feed on some mussels.

How do we get baby mussels?

  • Male releases his sperm
  • Female inhales it and mixes it with her eggs
  • Glochidia (larval mussels) are released into the water...
  • ...and attach to a certain type of fish
  • After growing for a while on the fish the baby mussel drops off and buries in the sediment where it lives for the rest of its life.

This complex lifecycle relies on a healthy fish population!

Why are they dying out?

Because mussels filter the water they live in they are sensitive to changes in pollution levels of rivers and lakes. Too many chemicals kill them.

A small amount of mussels produce pearls, so they have been killed to obtain their treasure.

Changes to the river, such as damming, stop fish swimming upstream. Mussels cannot breed then, because they need fish for part of their lifecycle.

Why should we care?

A healthy mussel population shows that the water they live in and the surrounding land is healthy and free from too many chemicals. This makes them good environmental indicators and therefore very good for us to keep around!

Mussels filter out bacteria and other particles from the water, cleaning it for us.

A healthy mussel bed can stabilise rivers and lakes because large numbers of them together hold the sediment in place.

Help to improve our environment, save our mussels and they will do the same for us!

Article Date: 24 July 2007

11 comments

clammy on 19 February 2012, 16:36

Is it common for freshwater mussels to be in Buckinghamshire, England. Because my family and I just found two and we want to know if it natural.

Amgueddfa Cymru on 8 September 2011, 12:27

Dear Chris Baines,
In some species of fish the larger the fish the more parasites they will carry. Many species of Anodonta and Unio glochidia (larvae) are not fussy about which species of fish they use as a host and Sticklebacks have been found infested with Anodonta glochidia. The larvae latch on to the gills or fins and drop off when they are able to fend for themselves, not harming the fish in the process.

Do you know what species of mussel you have? It will be one of two genera: Anodonta or Unio. If you are unsure and you would like to know then take a photo and email anna.holmes@museumwales.ac.uk so that I can identify it for you.

Here is a list taken from a paper published 14 years ago of fish that have been found to have freshwater mussel glochidia attached to them.

Best wishes

Anna Holmes
Curator (Bivalves)
Amgueddfa Cymru - National Museum Wales

Chris Baines on 7 September 2011, 15:43

I have introduced a few fresh water mussels to my garden pond from a local polluted canal, and they are thriving. I understand that they need fish as part of their reproductive cycle. i have avoided fish so far, but wonder if sticklebacks can serve as the host for the mussel offspring, or if a larger fish species is necessary.

Amgueddfa Cymru on 15 September 2009, 11:05

Thank you for your comments. We have posted up some identification information to help if you want to try and identify the species of freshwater mussel you have found:
ID 1
ID 2

orford on 18 August 2009, 08:50

we think we have found fresh water mussels in our pond what should we do ?

carol coulter on 11 August 2009, 14:31

I bought two mussels 5 years ago, and have them in a small wild life pond. ( no fish) and now I have hundreds of baby mussels.

Rosemary mackley on 22 January 2009, 17:49

Thousands were eaten --by birds--when the brecon canal was drained.Some up to 6 inches across. I presume these are NOT the pearl mussel Margaritifera margaritifera

liza on 3 November 2008, 12:14

i love this website!!!it has soooooo much info and i am using it for a huge project and it has helped so much.

user comment on 3 November 2008, 12:14

I have Tiny mussels in my pond how do I identify them, I live in Cardiff?

Amgueddfa Cymru on 3 November 2008, 12:14

Hi, Thank you for your comment,
If you would like to collect some mussels from your pond, you can bring them into the Glanely Discovery Gallery at the National Museum Cardiff where you will be able to view them under a microscope and ask staff to help you identify them. Different mussels like different places to live - two common mussels found in still ponds around the UK are called Sphaerium [the European fingernail clam] or Pisidium [the Pea Cockle] - you can try and find out if your mussels are either of these if you bring them into the Glanely Discovery Gallery.
Look forward to seeing you at the Museum!

Keith on 3 November 2008, 12:14

The lake in New York state I've been going to for over 30 years has always had a large healthy population of freshwater mussels. The lake is spring fed on top a mountain and the water seems to get good turnover.

This year for the first time ever I've seen empty mussel shells everywhere with the soft bodies floating around. it seems to be a sudden mass extinction... motorboat traffic has been about the same over the years. I'm wondering if it's people's septic leaching or resident using fertilizers on the now popular "look at me" lawns... where can i get more info so i can make some flyers to make the residents of this private lake aware of the situation? Thanks

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