what's a simple way to describe "anguilliform" undulatory movement of lampreys? and what's ondullatory mean?

Answer 1

I guess to be "eel-like" having no legs, being aquatic and posses functional or vestigial or reduced fins. Lamprey move by moving their bodies back and forth, to create propulsin, this is undulatory. Sinusoidal movement is what snakes use, it is side to side "S" movements, where as eels and lamprey use more of an up and down movement, like a mountain chain (several mountains side by side) they say the undulating mountains.

hope this helps!

Answer 2

To undulate is to move back and forth slowly and smoothly.