It's been years since I played "Morrowind", but I wonder if the kwamas who thumped their tails on the ground were listening for the hollow sound of caverns below them (similar to geologists today searching for oil using sound, if I've heard right). Maybe they were scouting for areas to expand? Proweler, Adanorcil and others would know more than I about this.
Wow - I never thought of that!
http://www.uesp.net/wiki/Morrowind:Kwama
Scrib: The larval form of the Kwama which is not very aggressive but can paralyze anything that attacks it.
(Is there then a pupal(?) stage?)
Forager: The forager scouts land and caves, searching for new colonies and prey. Though agressive, the Forager is not particularily dangerous.
Worker: The primary source of labour in a Kwama colonies, digging tunnels and attending to the Queen and eggs. It is not agressive unless provoked.
Warrior: Aggressive Kwama which protect the nest from invaders. These may be Kwama; but they can be extremely dangerous to low to mid level characters.
Queen: The largest of the Kwama which produces all of the nest's eggs. There is one Kwama Queen in every Egg Mine. They are too large to move and their needs are attended to by Kwama Workers. They are not aggressive unless provoked.
They seem quite similar to ants or bees.