The gooba is a benevolent creature that yields an excelent source of food, leather and bone.
Eup are more of a plant-like species that carry their own eco-system with them. The pile of dirt contained in the Eups pouch often yields rock, metal or wood. Eup are not particularly susceptible to poison.
The smard is a tough beast that can withstand quite a few arrows before he'll drop. Bringing down a smard will usually yield a good amount of food, leather and bone.
The female reemen, identifiable by a green iris and green toned skin, is easily frightened. Try not to get too close as she will dispense a dose of toxin causing your body to expel vital resources in the effort to combat the poison. The toxin can be cured immediately by ingesting a dose of antidote often found from the male reemen which can be indentified by a blue iris and grey toned skin.
Reemen are immune to poison.
Like gooba meloch are a good source of food, bone and leather, however; meloch are quite aggressive and will attempt to maul you. Try to take out meloch from a good distance, aim for the head if you're looking for a quick kill.