Neotropical Dragons are a breed that originate in rainforests. They are fun-loving and enjoy lounging on tree branches, eating whatever fruit they find. They are also often found sunning themselves on rocks, using their large wings to soak up the rays. In the summer, males compete for mates by showing off their striped wings and gliding in spirals down the tree trunks. It is said that the larger the wings, the more likely the male will attract a suitable mate.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Physiology is defined as the science of the functioning of living systems. Physiology, however, is more of a scientist. She wants to learn everything that there is to know about the tropical rainforest that she loves and the cave where she lives. She is generally kind to the other cave dragons, but Littletooth holds a special place in her heart. She loves to fly, and often takes the little mint out on flights.

It is reputed that Physiology has "more-than-a-friend" feelings for Littletooth, but she denies this.