Something is brewing in the open sea and yet the sailor dindnt fear me

I have six legs, wings and make a buzzing sound and though I'm small, I'm known near and afar. I'm a tiny creature. What am I?

Three letters make up my name, I twist, I slide and slither all the same. In rivers or oceans I wriggle with ease, What am I that moves as I please?

Up and down, top and side. Not big but small, rolling right along

I guard the fields with a prickly stare, Purple crowns upon my hair. Ignored by hands, yet bold and brave, I flourish where the wild things wave. Touch me wrong and you’ll soon see- What thorny symbol could I be? Want it harder, shorter, or with a mythicalhsymbolic twist?