This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For a blue mussel, a good meal does not come entirely without risk. Blue mussels feed by filtering microscopic algae from seawater.
But some unwelcome guests can slip in along with their food. Tiny parasite larvae can hitch a ride as the mussel pumps water in and out. New research from Aarhus University shows that blue mussels have a defense.
When they detect the risk posed by certain parasites, they simply reduce their filtration. And when things get particularly risky, they can even close their shells completely. This leaves the mussel with something of a dilemma: If it stops filtering, it stops eating.
But there is more at stake than the mussel's own dinner. A single large blue mussel can filter up to 100 liters (26 gallons) of seawater a day, and millions of mussels can congregate in large beds. Here, they act as ecosystem engineers.
By filtering microalgae from the water, mussels affect water clarity and nutrient cycling. The beds themselves also form a landscape of shells, gaps and crevices that provide habitats for small animals, fish and plants. So when fear of parasites causes mussels to cut back on one of their most important activities, the effects could potentially be felt on a much larger scale.
"That is what makes this response so interesting. We are looking at something that happens in an individual mussel, but because blue mussels play such an important role in coastal ecosystems, even small changes in their behavior could potentially matter on a much larger scale," says Ph.D. student Pernille Kibak, one of the researchers behind the study, which has just been published in the Journal of Helminthology. The researchers explored the phenomenon in a series of laboratory experiments in which they exposed blue mussels to larvae from three different species of parasitic flatworm.
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