Mussel of the

Page last updated
2 November 2005

Mussel of the Month

The November 2005 Mussel of the Month is Unio crassus. U. crassus looks like quite a plain-Jane mussel from Europe, but it has a truly bizarre spurting behavior.

Unio crassus
ANSP 48340. Scania, Sweden. B. Walker "Dr. Bods".

We have already had a species of Unio as the Mussel of the Month, Unio pictorum in October of 2003. Given the number of mussel genera that we haven't done yet, it might seem odd to come back to Unio so soon, but the news recently published by Heinrich Vicentini of this mussel's "spurting" behavior has earned it a spot in the limelight. Check out these pictures, courtesy of Dr. Vicentini:

Unio crassus spurting Unio crassus spurting

U. crassus crawls up to the edge of the water, exposing its excurrent aperture, and then lets loose a stream of water. The fountain of water often contains glochidia, and Dr. Vicentini suggests that this spurting behavior may facilitate dispersal of mussel larvae. This makes us wonder what other sorts of mussel behaviors are waiting to be discovered — especially among the species that are not as well-known as Unio crassus!


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily Unionoidea Rafinesque, 1820

Family Unionidae s.s.
Subfamily Unioninae s.s.
Tribe Unionini

Genus Unio Philipsson in Retzius, 1788

Species Unio crassus Philipsson in Retzius, 1788

For more information on the spurting behavior of Unio crassus, check out the following:
  • Vicentini, H. 2005. Unusual spurting behavior of the freshwater mussel Unio crassus. Journal of Molluscan Studies 71: 409-410.
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