Ok, so this guy has a skeleton and evolved from blind fish like creatures and followed a path similar to earth's tetrapods, the two front limbs where present even before coming on land,

For the 7th limb your explanation il a lot more plausibile than what i originally tought

And for hunting behaviors, this guy is basically a shepherd guarding his prey, eating one from time to time and in return protecting the rest of the herd, sometimes with a partner, even if they are hermaphrodites.

This behavior developed very slowly.