Not all important changes are necessarily visible, as one can verify from any textbook of comparative physiology.

Heinrich is distinguished by his research work in the comparative physiology and behavior of insects.

"I've started making some notes for a reference book I've been considering writing, on comparative alien physiology."

A number of scientific societies feature sections on comparative physiology, including:

It is closely related to comparative physiology and evolutionary physiology.

Unity in Diversity: A perspective on the methods, contributions, and future of comparative physiology.

His "baby" from the zoology years was General and Comparative Physiology.

Functional differences between mitochondria from different species are studied by respirometry as an aspect of comparative physiology.

His study was published recently in The Journal of Comparative Physiology.

A systematic treatise on comparative physiology, introductory to the Physiology of man.