Hexarthra mira (Hudson, 1871)
Most likely ID: n.a.
Synonym: Pedalia mira
Sampling location: Lake Constance, Hagstaffel pond, Mühlhalden pond, Pond of the waste disposal company Constance
Phylogenetic tree: Hexarthra mira
Diagnosis:
- body cone- or bell-shaped
- length 160–400 µm
- six arm-like rudders with delicately feathered bristles
- two eyespots
- two cylindrical appendages with cilia at distal end
- rotatory organ almost 8-shaped in apical view with inner and outer ciliated rim
- planktonic lifestyle
Hexarthra mira is a planktonic rotifer with a very complex shape. With the help of its 6 arms, which are all moved by strong muscles, it can perform fast jumps. Very often I find Hexarthra mira in the pond of the waste disposal company Constance, although it is heavily eutrophicated and has a high fish stocking. At the same time Hexarthra is also present in Lake Constance, which has drinking water quality. So the demands regarding water quality do not seem to be very high.
More images and information on Hexarthra mira: Michael Plewka-Freshwater life-Hexarthra mira
Fig. 1 a-c: Hexarthra mira. L = 200 µm (with arms). Different focal planes of a freely swimming specimen. Obj. 40 X.
Fig. 2 a-b: Hexarthra mira. L = 200 µm (with arms). Two focal planes of a lateral view from right. Note the complex arrangement of striated muscles (SM) to move the arms and the appendages with a tuft of cilia (CA) at the distal end. LA = lateral arm, VA = ventral arm. Obj. 60 X.
Fig. 3: Hexarthra mira. A specimen with a brownish resting egg (RE). The surface of the resting egg is covered with short tubes. Obj. 60 X.