Spasm

Sudden involuntary muscle contraction

Be Symmetrical

Exhibit symmetry, have corresponding or harmonious arrangement

hiss

Animal noise similar to a growl

crawl / slither

Movement verb(s) for snakes, bugs, and animal generally low to the ground

nod

A simple nod for yes, a nod at/toward something (or as a direct object). Related words could include shaking head for no, tilting head questioningly,…

Look at / stare

We have legh for see, but we don't have a word for actively directing the eyes

blackmail

extort money or benefits from someone in return for not revealing compromising information

wink

To close and open one eye.