Hope my actions suit the situation.
Since the tentacles latched on I figure they are in reach and so a full attack.
Otherwise I might be able to jump up (move action) and smack him one at +12, or even jump and grab a tentacle and hold on (improved grapple) so others can smack it in melee.
Checking out the synergy and movement bonuses it turns out I've got a +22 on jump, how high would I have to jump to hit it or to grab a tentacle?