Order Unionoida
The Unionoida (Order Unionoida) includes 3 species across 1 families and 2 genera in our directory.
About Unionoida
This is a smaller arthropod order with specialized ecological roles. Arthropods are the most diverse animal phylum, comprising over 80% of all known animal species with approximately 1.2 million described species globally.
Economic Impact
While this order has limited direct economic impact, arthropods collectively provide ecosystem services worth trillions of dollars annually through pollination, decomposition, pest control, and nutrient cycling.
Ecological Role
Members of this order contribute to broader arthropod ecosystem functions including decomposition, predation, and serving as food sources for vertebrates. Arthropod biodiversity is essential for ecosystem resilience.
Families in Unionoida (1)
Species in Unionoida (3)
Duck Mussel
Anodonta anatina
One of the largest of our freshwater bivalves, typically 75mm but up to 120mm in length. It has a thin shell and is generally slim when closed. Brown and yellow in colour. The hinge margin is notably angled from the mid-axis. The Swan Mussel, Anadont
Painter's Mussel
Unio pictorum
Typically 70-80mm long but can be over 100mm. Elongate with the length at least twice the height. The hinge is long, straight and horizontal. The shell is usually a yellow/olive colour with brown growth lines visible. It is only likely to be confused
Swan Mussel
Anodonta cygnea
This aquatic bivalve mollusc is a large species of freshwater mussel. The shell is thin but large (approximately 10 to 14cm when adult) and rather flat, even at the umbo. The shell colour is often pale greenish or brownish. Younger specimens can be d