> Comb jellies are ancient marine predators whose hairlike extensions known as cilia refract light as they swim, giving them an iridescent shimmer. They are the largest animals known to use cilia for movement, ...
I've long wondered: What is the difference between cilia and flagella? I've found no authoritative source that differentiates them or that says they are the same (except one paper from decades ago that strongly implies they are the same). It seems like something insiders know implicitly and never bother explaining.
Because a clear distinction is lacking, I don't trust non-expert sources like Wikipedia to be consistent, tor to not confuse them or miss any nuance.
> What is the difference between cilia and flagella?
Broadly and generally:
• cilia come in large groups, in rows or in sheets; flagella come singly or in pairs (occasionally more)
• cilia are short, and they beat backwards and forwards in a coordinated way, like a Mexican wave; flagellae are long, and in prokaryotes, they spin around their axis.
(Eukaryote flagella -- e.g. spermatozoan "tails" -- are a different structure that just resembles the ones in prokaryotes. Prokaryotes are bacteria and archaea -- no cell nucleus. Eukaryotas have cell nuclei and other organelles, such as mitochondria and chloroplasts. Their flagellae bend and flap, they don't spin.)
Take 1 cell. Can you count the moving hair things? Then they're flagella. Is the beastie covered in lots of them, countless, like fur? Then they're cilia.
Thank you very much.
> in prokaryotes, they spin around their axis.
I read earlier this year about Berg's and Samuel et al.'s (and maybe others') amazing flagellar motor discoveries. I didn't realize they were only prokaryotes; the motor seems like a sophisticated mechanism.
> What is the difference between cilia and flagella?
There are clear structural differences at microscopic level. they are fueled differently. In short, cilia are like eyebrow hairs, short, weak and simple. They appear in groups of tens or thousands, while flagella are like head hairs, unique or double, rarely more than three, and much longer, thicker and more potent, so faster. Structurally more complex also.
They move in a different way also. Lets say that cilia move like a pendulum and flagella moves like the ribbons in rhythmic Gymnastics
Thanks!