Margaritifera margaritifera

 

Scientific name: Margaritifera margaritifera

Common name: Freshwater pearly mussel

Origin: Europe

Family: Margaritiferidae

Genus: Margaritifera

Size: 8 to 15 cm

Breething: aquatic, through gills

Temperature:  0 to 25°C

Utility: filters water

Remark:   big sized species are only fit for major size aquaria or ponds. Indicator of water quality, populations are presently tending to decrease.

Particularity: filters up to 2 liters of water per hour, consuming the organic particles suspended in water. Shell is long, slightly swelled, color is dark brown to black. The  Apex is often corrugated. Cardinal tooth of the right valve is thick and toothed.  Posterior edges of the mantle are not welded in order to form a separated anal aperture.

 

Lamellibranches have gills in the shape of thin blades and their shell is composed of two valves that are approximately symetric.  These are very apathic animals, that react to light by closing their valves when the light source is intercepted.  Some remain almost completely dug in into silt, and only leave out their posterior extremity that corresponds to the longer part of the shell.

The reproduction mode is quite interesting as Unios, Anodonta and Margaritifera are gonochoristic.  Eggs are very numerous and tiny; these are fertilized and incubated in females palleal cavity.  When they hatch, the larvae - called glochidia - are expelled and must find a host in order to continue their development. They must be swallowed by a fish; they will then attach to its gills and remain there in a cyst until their morphology is similar to adults. this doesn't harm the fish in any way, and when the young bivalve has acquired its final aspect it will simply drop to the bottom.  Aquarists report success in the reproduction without a need for glochidia  hosts.

Blades opening - Zoom on the mantle. One might think they are showing their tongue ?! In fact this is the foot searching for a surface in order for the mussel to switch position.

Summary