Grévy's zebra
The Grévy's zebra is the largest of all wild equines. It is from head to tail with a tail, and stands high at the withers. These zebras weigh . Grévy's zebra differs from the other two zebras in its more primitive characteristics. It is particularly mule-like in appearance; the head is large, long, and narrow with elongated nostril openings; the ears are very large, rounded, and conical and the neck is short but thick. The zebra's muzzle is ash-grey to black in colour with the lips having whiskers. The mane is tall and erect; juveniles have a mane that extends to the length of the back and shortens as they reach adulthood.
Zebra mussel
The vast majority of the organisms that are natural enemies in Europe are not present in North America. Ecologically similar species do exist, but these species are unlikely to be able to eliminate those mussels already established and will have a limited role in their control.
Crayfish could have a significant impact on the densities of 1- to 5-mm-long zebra mussels. An adult crayfish consumes around 105 zebra mussels every day, or about 6000 mussels in a season. Predation rates are significantly reduced at lower water temperatures.
Fish do not seem to limit the densities of zebra mussels in European lakes. Smallmouth bass are a predator in the zebra mussels' adopted North American Great Lakes habitat.