This video shows the characteristic "falling leaf" motility of Giardia. I really like how you can see the shape of the trophozoite in this video. Note in the still shots below that is somewhat flattened laterally and therefore looks like a leaf. It helps explain the pattern of motility that we see.
It is only when the troph turns to show its ventral-dorsal aspect that we see the classic piriform (pear) or 'kite' shape of the trophozoite:
And now our poem from Blaine Mathison!
Giardiasis has often been referred to as Beaver Fever
Not to be confused with the phenomenon about a certain singer
And this parasite has much better dancing moves
as it winds through your lumen to a flagellar groove
And with no annoying ‘pooparazzi’ life couldn’t be sweeter!
(For those of you who aren't up on the latest pop culture [like me], Blaine is referring to Justin Bieber and the bewildering phenomenon of Bieber Fever - yes folks, that really is a thing)