Stingrays....

[Holy Mackerel]

Figured it's a Bat ray, had a couple eat my bait in recent weeks.

http://en.wikipedia.org/wiki/Bat_ray

While the bat ray, like other stingrays, has a venomous spine in its tail (near the base), it is not considered dangerous and uses the spine only when attacked or frightened.

FWIW, I have been shaking the hook loose at boatside with that tail whipping around, now on second thought a hook will rust out.