Conochilus hippocrepis Schrank 1830
Conochilus hippocrepis, a pelagic rotifer. The arrow points to the two lateral antennas which are separated from each other, which separates this species from Conochilus unicornis. Colony from (3).
Conochilus hippocrepis, colony from (2).
Conochilus hippocrepis, excerpt from colony from (2).
Conochilus hippocrepis, corona of specimen from (3). In contrast to the corona of the flosculariid rotifers Beauchampia, Floscularia, Limnias, Ptygura, Sinantherina, which have a closed circular corona, the corona of the Conochilidae is open, i.e.: horseshoe-like (see image below). The outer ciliated ring is the trochus; the inner ciliated ring widens in the middle to the buccal field of the oral cavity.

Conochilus hippocrepis, corona of specimen from (4). In contrast to all other rotifers observed up to now (where the metachonous beating of the trochal cilia is counter-clockwise) the apparent "turning of the wheel" i.e. the metachronous movement of the trochal cilia of this species (genus??) is clockwise (orange arrows). What causes this different direction is not known. The whole "circle" (actually the ciliary wreath is interrupted at the ventral side) seems to be divided into 24 wave packets (some of which are marked by arrowheads).

Maybe this is also the reason for the "reverse" swimming of single specimens of Conochilus: foot is front; corona is back while swimming.

aF: apical field; bF: buccal field; Ci: cingulum; Tr: trochus.

Conochilus hippocrepis, ventral view; in contrast to Conochilus unicornis this species has two more or less separated lateral antennas (2).
Conochilus hippocrepis, dorsal view; focus plane on the red eyespots.(2)
Conochilus hippocrepis, dorsal view; snapshot of the metachronous beating of the trochal cilia. 6 of the 24 wave packets are in focus here. From observations with footage recorded at 180 fps it can be calculated that the speed of "rotation" is ≈ 40 rpm. Also visible is the dorsal antenna (arrowhead) (4)
Conochilus hippocrepis, juvenile specimen, hatched 4 minutes before (4)
Conochilus hippocrepis, juvenile specimen (hatched 15 minutes before this image was photographed), lateral view, showing the position of the right lateral antenna in relation to the right eyespot. (4)
Conochilus hippocrepis, same juvenile specimen, dorsoventral view. The cilia of the corona seem to be stil covered with a membrane from the egg shell. (4)
Conochilus hippocrepis, to aspects of the malleoramate trophi, different focal planes (3)
Conochilus hippocrepis, colony from (1)
Location (4); : Henrichsteich, Hattingen, NRW, Germany, pond
Habitat (4); : plankton-sample with algae and detritus (click image to enlarge >>>)
Date (4): 24.07.2022
Location: NSG Schwalm, Venekoten-See (1); NSG Heiliges Meer; Großes Heiliges Meer (2); Glör-Talsperre, NRW, Germany (3)
Habitat: Plankton (1;2); Plankton / between plants (3)
Date: 03.09.2011 (12); 21.04.2017 (2); 21.05.2021 (3)
freshwater life
marine life