UNIO PICTORUM

 

Scientific name: Unio pictorum

Origin: Europe

Family: Unionidae

Sub-family: Unioninae

Size: 8 to 15 cm

Breething: aquatic, through gills

Temperature:  0 to 25°C

Utility: filters water

Remark:   big sized species, Unios and Anodonta, are only fit for major size aquaria or ponds.

Particularity: filters up to 2 liters of water per hour, consuming the organic particles suspended in water.

 

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, like Unios and Anodontes, 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 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.

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