Hurkles are happy-go-lucky animals, and on Lirht "The hurkle are highly regarded by the gwik as pets, in spite of the fact that a hurkle is so affectionate that it can have no loyalty." Hurkles have the valuable power, on Lirht, to "become invisible if frightened." These aspects of the hurkle are crucial to its behavior on earth; it is an animal that could itch humans to madness with its affection while remaining completely friendly, with no malice at all.

The characters of "The Hurkle Is a Happy Beast" are sketches; the humor and the theme are more important than character development. Even so, Sturgeon provides a detailed description of the hurkle kitten that has been transported to earth: It was blue—a truly beautiful blue. It had a small spherical head and an almost identical knob at the other end. There were...