Answer:
My days are numbered.
I grow up while growing down
I am long and slim works in light. Has but one eye and an awful bite.
With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?
Fatherless and Motherless, born without sin. Roared when it entered the world, And never spoke again.
If you can spot one of these eastern warriors, it means they're not doing their job right.