Crossing paths with the endangered freshwater pearl mussel (Margaritifera margaritifera)

in nature •  4 months ago

It's not all that common to actually randomly stumble across an endangered species of animal, especially here in Norway where we have a rather low biodiversity compared to warmer regions closer to the equator. Still, it does happen from time to time, and two days ago I actually found a population of freshwater pearl mussels (Margaritifera margaritifera) when I was going for a swim.

DSC_0220 – Kopi.JPG

It's certainly not the best photograph ever taken of this species, but I did the best I could. The water was not all that clear, and I have neither equipment nor experience when it comes to underwater photography, so I just did my best to shoot it from above the water.

This invertebrate is actually pretty rare these days, but they are still found in several rivers in most of Europe and in parts of North America. Like you would guess from its name, it can create a pearl, so the species faced a huge hunting pressure during the 19th and 20th century where poor people could be lucky and find a pearl, which was very valuable at the time.

These days the mussel is protected in all European countries, but it's still facing a population decline in almost all rivers, due to its sensitivity to pollutants such as heavy metals that we humans tend to throw away into nature. The species can actually be used as an indicator species, and its presence will tell us that the river is rather healthy. This is a very nice and easy way to get a good indication of the health of the river without having to run chemical tests. Just keep in mind that it does not work the other way around; the absence of this species does not necessarily indicate an unhealthy river.

While searching the small area close to where me and my family were swimming, I found around 10 individuals, but I would assume that there are many more that were hidden from my view (which was rather limited).

A small funfact about these is that they used to be called Elveperlemusling in Norwegian, which directly translated to "River pearl mussel". This gave away the "secret" that they could contain a pearl, so the official name was changed to Elvemusling, meaning "River mussel". So these days you will have to do some research to learn that these do indeed contain pearls.

The chance of it containing a pearl is extremely low though! A typical saying is that one in a thousand has a pearl, and only one in thousand pearls are actually worth anything. On average you would then have to kill and open 1,000,000 (one million) mussels to get a pearl that was actually worth something.

Anyway, I do realize that it's really difficult to tell exactly what it is you're looking at from my photo, so here's another photo taken by a much more skilled photographer:

This photo is taken by Joel Berglund, and is posted under the Creative Commons Attribution-Share Alike 3.0 Unported license. It shows a group of the freshwater pearl mussels in Sweden, and you can clearly see them filtering water to search for small particles of nutrients.

Thanks for stopping by and checking out my post and photo of the freshwater pearl mussel. I hope you enjoyed it, and maybe even learned something about this invertebrate.

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Great and amazing photography @valth. I really liked your post. I appreciate your work. Wish you all the best.

Thanks for sharing this post. ☺💚


Thanks! I'm glad you liked it :)

Ohhh... So you have found a healthy population elvemuslings.... That is great...
And the heavy metals like Cr, Pb and As are really a problem... Dangerous to everyone...


Yep, the heavy metals you listed will serious damage all life that comes into contact with it. These filter feeders are probably the first ones who die from it, which is why they are such good indicators. I would feel confident drinking water from this river since these mussels are doing fine here :)

That must have been a very interesting encounter :) I also like wild swimming (in our lakes and rivers) but the only mussel species I have seen here in the Czech Repulic is this one:

Btw the underwater photo you took looks pretty cool ;)


Yeah, it sure was :) That's a nice species to come across as well, but luckily the swan mussel is not that threatened. We have it in Norway as well, but it's only been registered in three different lakes, so I don't expect to stumble across that one any time soon.

I see that you have the freshwater pearl mussel in the Czech Repulic too, but it's considered Critically Endangered there, so I bet it's rare to find.


Man, you never fail to educate me :) It is embarrassing for someone who consider himself a nature lover like me but I didnt even know we have the pearl mussel in my country! I just checked some Czech articles on this topic and you are 100% correct. It only lives in two little rivers in the south-western part of the country. Thank you for broadening my horizons again :)


Hehe, don't worry about it. It's impossible to know every single species you have in your own county! It's just too many of them :P


Swan mussel
The swan mussel, Anodonta cygnea, is a large species of freshwater mussel, an aquatic bivalve mollusc in the family Unionidae, the river mussels.
Because of its morphological variability and its wide range of distribution, there are over 500 synonyms for this species.

A good find! I was pleased to see that oysters have returned to the coast around Ramsgate following the huge cleanup of the beaches. I'm not sure whether these ever have pearls but they are sought after as a food along with a natural coastal vegetable, samphire. The oysters seem to survive, though, and colonies are thriving. Their shells are very beautiful and I often collect those when I am visiting.


Thanks! I'm glad to hear that the oysters are back in that area. It's a great source of gourmet food as well, so I can totally see why you love to pick them when you are in the area ;)

Oe, so if the river has pearl shells in it, that means healthy river water.
Oa, is this pearl shell edible?
Have a good day @valth


I don't even know. But it's protected, so it would be illegal to eat it.


Oe, yes, because the pearl shells are rare now. So the goverment must protect them.


Yes, that's correct :)

Nice what is this


It's a freshwater pearl mussel.


OK thanks for appreciate my work

You have a minor misspelling in the following sentence:

It's not all that common to actually randomly stumble accross an endangered species of animal, especially here in Norway where we have a rather low biodiversity compared to warmer regions closer to the equator.
It should be across instead of accross.


Thank you for letting me know! Good bot :)

This is very adorable. I read about this pearl producing species when was a kid. I thought that I would find like this one day and become rich :p
But i couldn't find one because they are actually not found in my country.
Hope you find for yourself:D


Hehe, that's a cool story!

Virginia’s unique natural heritage
includes aquatic communities and
ecosystems such as in tidal and
nontidal wetlands, the Chesapeake Bay
estuary, the Atlantic Ocean coast and 49,000
miles of rivers. These marvelous natural
environments are home to more than 10,000
animal species and thousands of plant
species – some of which are endangered or


Yes, that's true, but has nothing to do with this post :P

@valth very beautiful photography. loved to see


Thank you :)

This photography is a remarkable occasion for a beauty seeker who has an aesthetic thirst for poetic feeling.....


Thank you.