Biodiversity Fact File: Mighty Horse Mussels

Thursday 27th April 2017

Horse Mussel Reef © Rohan Holt

Horse mussels are some of the smaller marine creatures around our coast, but that doesn’t make them any less mighty! We've put together some interesting facts about this important marine species.

Horse mussels differ from the blue coloured edible mussel, which we often see coating rocks and pier structures around the Island. They are much larger, measuring 10-20cm long with glossy brown shells. The bivalve which lives inside has pale coloured lips rimming the shell and can survive in depths of five- to as deep as 70 metres.

Horse mussels also live for quite a long time, up to 50 years in some cases. That is, if they can avoid being eaten by their main predators, starfish and crabs. If they are able to grow to 6cm they have a greater chance of surviving. These creatures are filter feeders and survive in strong currents, which are prevalent at Point of Ayre and you can clearly see this area has strong currents if you watch the bubbling sea surface here.

Horse Mussels © Rohan Holt

What makes these muscles so mighty is their ability to band together to form very important habitats. The mussels attach themselves to the seabed by strong hair like threads called byssus threads, you can see these also on the edible mussels you may find along the shore line. Because of this strong hold on the sea floor, they can help stabilise the soft sediments of the sea bed. Over time, the empty shells along with the living mussels can build up extensive reefs .

Shark eggs on Horse Mussel Reef © Phil and Caroline Roriston

These reefs form an important habitat for a variety of marine life. The nooks and crevasses between the horse mussel shells provide hiding places for young fish, whilst on the shells themselves barnacles, tube worms, and sea mats can colonise, so they provide an excellent underwater habitat.

In fact they support such a varied sea life that they are listed as one of the priority habitats in the UK biodiversity action plans. This species also has its own protection zone in the Ramsey Marine Nature Reserve. A fascinating world which we can’t see, but never the less is of great importance to us with coastal erosion issues and impacts on the scallop and fishing industry.

As you can see, the Isle of Man really does have a very diverse variety of life which we are learning more about every day. Why not come to one of our many events which will help introduce you to our biodiversity and is a great way to meet likeminded people. Find our events on the What's On page or keep up to date with us via our Facebook page.

Tagged with: Biodiversity, Habitats, Horse mussels, Living Seas, Marine