Flagellate

Flagellates are single-celleded protists with one or more flagella, whip-like organelles often used for propulsion. Originally they were grouped together as the class or phylum Mastigophora, but the different lines do not appear particularly closely related. These include:

• Retortamonads
• Diplomonads
• Oxymonads
• Parabasalia
• Jakobids
• Heterolobosea (amoeboflagellates, etc)
• Euglenozoa (kinetoplastids, euglenids, etc)
• Ebriids
• Ellobiopsids
• Dinoflagellates
• Haptophytes
• Stramenopiles (golden algae, bicosoecids, etc)
• Cryptomonads
• Green algae
• Choanoflagellates

It is quite possible the ancestral eukaryote was a flagellate, and if not they appeared fairly early on in their development. The animals, fungi, and plants are all derived from various lines of flagellates - something reflected in the presence of flagellate cells in most forms, whose ultrastructure is a useful guide to determining relationships.