Complex sentence: They want Frisby to add to their collection of specimens from other planets--they accept his exaggerated tales at face value, and Frisby appears to have the widest range of experience and widest education amongst humans (they've heard him claim eight doctoral degrees).
Split into simpler sentences: They want Frisby to add to their collection of specimens from other planets. The aliens accept his exaggerated tales at face value, and Frisby appears to have the widest range of experience and widest education amongst humans (they've heard him claim eight doctoral degrees).