the small ones as ‘cilia’, the large ones as ‘flagella’. Cilia are common in animal cells, for instance in our nasal passages, and they cover the surface of those protozoans called, not surprisingly, ciliates. Another traditionally recognised group of protozoans, the flagellates, have much longer, whip-like ‘flagella’ (singular ‘flagellum’ and, unlike cilia, they often are). Cilia and flagella share an identical ultrastructure. Both are like multi-stranded cables, and the strands have exactly the same signature pattern: nine pairs in a ring surrounding one central pair.
