Monday, September 7, 2015



Understanding the story of animal evolution is very dependent on knowledge of invertebrates.  Vertebrates are recent (ok, the last half billion years), but very important, contributors to understanding the evolutionary history of animals.  Darwin mostly used vertebrate examples in explaining his understanding of natural selection, Darwin's finches being the primary example.  His studies of domestication of vertebrates also helped.   But he also contributed to our understanding of invertebrates such as coral reefs, barnacles, and earthworms.

What make invertebrate zoology so useful?

There are many species representing different parts of the evolutionary tree of life.  They provide steps along the transition from simple to complex structure and diversity.  As research subjects many of them have the advantages of
1 short life cycles
2 small size
Together it greatly simplifies getting adequate data in studying many phenomena.  It keeps costs down for care of subjects and allows varied approaches to be used in a short time.  The ethical problems of care of subject animals seems less, but should not be ignored.
3 abundant numbers are usually available in nature for field observation.
4 many extinct species have left fossils; their small size often providing intact fossils.

Examples of contributions of invertebrate zoologists

E. O. Wilson observed social behavior of ants and other insects and conceived the sub-discipline of ecology and/or animal behavior termed SOCIOBIOLOGY.

Paul Ehrlich developed his understanding of population ecology, in part, from his studies of lepidopterous insect populations, and applied it to his concerns for overpopulation by humans in an influential book, The Population Bomb.

Alfred Kinsey transferred from years of studying wasps to studies of human sexuality.

Libbie Hyman [ ] studied hydras and planarians and stayed mostly an invertebrate zoologist of great breadth.

Robert Pennak was my hero for his excellent book on aquatic invertebrates of the United States.  It has an excellent introductory discussion of the the transition of marine groups to fresh water.

Robert Barnes wrote an excellent invertebrate zoology text, especially in coverage of his specialty, polychaete worms.  If he had put insects and parasites in his first edition I would probably never have undertaken the revision of Hegner's invertebrate zoology text.  Meglitsch produced an impressive invertebrate zoology text that never received the recognition of Barnes' text which had largely been adopted by invertebrate zoologists.

A two volume text by Beklemishev (translated from the Russian) was a remarkable comparative anatomy of invertebrates.  Its value as a reference is somewhat marred by his belief that animals should be grouped according to the extent of their segmentation.

As invertebrate zoology becomes a minor part of biological education in today's universities, it is unlikely that it will attract authors to update the subject to the extent it was done in the past.  The digital age has made it unlikely that many will read the specialty journals and be exposed serendipitously to insights inspired by seemingly unconnected topics.  On the other hand, I have seen some weird results produced by search engines, so maybe there is hope.

Why did I become an invertebrate zoologist?

The reasons are somewhat lost in time.  But my first application for graduate school was to a botany department.  I had actually had more interest in invertebrates from using Hegner's Invertebrate Zoology text.  The variety was amazing, there were so many species, I thought maybe I could become the world's expert in some obscure group (I don't think I was very competitive).  I had been a little put off by the extreme need for grades motivating pre-Med student friends.  Plants were soon eliminated along with vertebrates due to sneezing and wheezing triggered by pollen and animal dander, factors seldom a problem with aquatic animals.

I had some vague notion that I might make some momentous discovery studying an obscure invertebrate.  I knew that was unrealistic.  Even so, dabbling in varied topics, I seem to be the only zoologist who realizes the abandoned annelid theory should be reinstated with modification to include the role of the pogonophorans as a central part of the theory.  The evidence that abyssal animals can live extremely long lives [ ] and provide reason molecular phylogenies need reworking is something I hope to make others understand.

Joseph G. Engemann      Kalamazoo, Michigan     September 7, 2015

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