Flagellate
Posted: Wed Jul 01, 2020 6:48 am
I found a relatively large flagellate in a pond sample. No clue about the name:
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Peranemids are "anterior gliders," which means they have a long, thick anterior flagellum, used for "gliding motility" (forward motion is produced on the surface of the flagellum, without the need for any movement). The single emergent flagellum we see here is short, fine, and moving very energetically. We don't see gliding motility. The cell is very metabolic (showing euglenoid movement), and non-photosynthetic (a heterotroph). It seems to lack an eyespot. So: Astasia seems likely. Some traditional Astasia species have been moved to Euglena and similar euglenoids are often placed in Khawkinea, but I think the lack of an eyespot rules those out. However, I'm not particularly sharp at euglenoid identification.
See what you mean about the flagellum, does seem a little short and overly energetic :)Bruce Taylor wrote: ↑Wed Jul 01, 2020 2:40 pmPeranemids are "anterior gliders," which means they have a long, thick anterior flagellum, used for "gliding motility" (forward motion is produced on the surface of the flagellum, without the need for any movement). The single emergent flagellum we see here is short, fine, and moving very energetically. We don't see gliding motility. The cell is very metabolic (showing euglenoid movement), and non-photosynthetic (a heterotroph). It seems to lack an eyespot. So: Astasia seems likely. Some traditional Astasia species have been moved to Euglena and similar euglenoids are often placed in Khawkinea, but I think the lack of an eyespot rules those out. However, I'm not particularly sharp at euglenoid identification. :)
Yes, in locomotion peranemids hold the flagellum stiffly forward, as shown in your image. The bent tip beats and twitches, but doesn't really contribute to forward movement (if it is chemically immobilized, the cell can still glide forward). When a peranemid is squirming in place, the flagellum relaxes and may thrash about, but it is fairly thick and the movements are somewhat languid.