Despite there being ‘ between 10 and 35 million of them covering every hard surface’ in the waters of Cardiff Bay, I’d never heard of the Zebra mussel (Dreissena polymorpha) until I posted a photo on Twitter back in March, asking what this Coot was eating (The Coot and the Zebra mussels, 11 March). Since then, I’ve noticed Coots eating these mussels on a regular basis but, even with the hundreds of Coots in Cardiff Bay, I doubt they’ll make much of a dent on those Zebra mussel numbers.