While they are not intelligent, they are naturally cunning and fierce creatures with a large appetite. They seem to be particularly fond of Spathi meat, but aren't very interested in humans. They will still ferociously attack humans if they come too close though.
These creatures appeared in large numbers on Spathiwa, seemingly out of nowhere "as though they had arrived suddenly on the surface of our planet transported there by some unknown agency". While it isn't explicitly stated, this sounds an awful lot like an Umgah joke.
Their appearance caused the Spathi to advance from bronze age to atomic technology in less than a century, until they reached the technological level to leave their home world for their inhospitable moon, where they have lived for three hundred years at the start of the Star Control II game. Curiously, despite their rapid advancement of technology, the Spathi imply that they never developed anything capable of overcoming the Evil Ones (although they may have simply lacked the courage). The Captain has the option of neutralizing these creatures, thereby allowing the Spathi to return to their homeworld and laying the foundation for an alliance between humans and Spathi.