Zebra mussel
(Dreissena polymorpha)Relationsship and features of typical shells (taxonomy)
Zebra mussel left valve |
Zebra mussel dorsal view |
Zebra mussel right valve |
Zebra mussel ventral view |
Appearance
Angular pointed, triangular shell with umbo situated on the pointed anterior end (shell shaped like that of the marine mussel Mytilus edulis). Total length: 25 - 40 mm. The two valves are V-shaped with the dorsal side flattened. The insertion forms a marked ridge on the outside throughout the shell length. Juveniles have a distinct zig-zag pattern in colour from brown to darker brown on a light background. The pattern becomes not so distinct among adults, which are a darker brown colour all over.Biology
The species is abundant in lakes as well as rivers and streams. It attaches by its byssus to anything solid. Local mass appearance is not uncommon. Before the nineteenth century it was restricted to the region of the Black and Caspian Seas, but spread rapidly, largely by sea treading, westwards in the first half of the century. It appeared into Lake Mîlaren of Sweden around 1920. Distribution
Locally common. So far it has been found in the Lake Mälaren and Lake Hjälmaren and rivers and streams connected with them. It is also appears scattered in the archipelago belonging to the Baltic Sea.Photo: Håkan Holmberg
Scientific basis: Ted von Proschwitz
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