Updated 07/27/09

A new theory about: Why insects have small bulks?

Before explanation of my new theory, I point out to those theories which have been presented before on this respect.

Exoskeleton theory:
Insects have exoskeleton and this theory point out that this skeleton isn't able to grow more actually, the insect is imprisoned inside this skeleton and isn't able to get larger. Defects of this theory: All of arthropod owns exoskeleton, and some of them like crabs are able to own rather large body which is discordant with this theory. On the contrary, there are some insects that own softer exoskeleton, but again aren't able to enlarge. Also in the past (250 million years ago), there were insects that owned big bodies (like dragonfly by length of 75 cm) and this theory can't explain the reason of their existence. Because they owned hard exoskeleton too but they were able to enlarger!

Respiratory system theory:
Insects respiratory system comprise thin and capillary tubes called tracheae that supplies oxygen directly through existent pores on the body, to all insect bodies interior cells. That means, opposite other animals, oxygen isn't been carried by blood. It flows through inside of tracheas by means of propagation phenomenon, and reaches cells.  This theory says that the propagation of oxygen inside the cells, is possible only in short intervals and if insects have large body, the length of tracheas will lengthen and oxygen can not reach cells. So insects are forced to own small body. About existence of large insects in the past, this theory predicts the existence of high percentage oxygen in earth's atmosphere. According to this theory, atmosphere's oxygen amount, 250 million years ago, was higher than the oxygen, would make it possible the propagation of it through the long tracheas of insects. Therefore insects at that time were able to be longer than present insects.

Defects of this theory:
250 million years ago, there were plants from the class of Horsetails and Club moss as the shape of very big trees. But today, the same plants exist only in very small size of some centimeters. Botanists believe that high consistency of atmosphere's carbon de oxide (CO2) is the reason of existence of giant Horsetails and Club moss at that time. You consider that entomologists predict a high consistency of oxygen and botanists predict a high consistency of CO2 for 250 million years ago. These two have confliction with each other.

This was a brief of theories existing in this respect. My new theory, in this respect:
Blood circulation system theory:
My theory is based on animals' blood circulation system. The theory compares the power and evolution of blood circulation system for animals and expresses the relation between bulk largeness and power of blood circulation system. According to this theory as much as blood circulation system is stronger and complete, animals' bulk can be larger (bigger). Insect's blood circulation system is too incomplete and there are no blood vessels. Insect's bodies, with lack of blood vessels, aren't able to supply blood consisting nutrition to remote cells, so their body are forced to be small. In this theory air pressure and gravity, are two physical factors that have impact on function of blood circulation system. The most effort of blood circulation system is used to conquest on gravity. As much blood circulation system is strong, is more able to conquest on gravity and send blood upper into animals' brain. Consequently, animal is able to enlarge more and taller. For example, elephants and giraffes, who own the most evoluted and strongest blood circulation system, are the largest and tallest ones among the animals.

For possibility of existence of insects whit big bodies and other big animals like dinosaurs and mammals in the past, this theory predicts a light gravity at that time. According to this theory, the amount of gravity in the past have been less than the present time, so blood circulatory system of animals was able to conquest better on it and enlarge animals body but along the time, gravity has been increasing and animals are forced to make smaller their body sizes.

As you know, there are some theories such as strike of meteorites or activity of volcanoes for extinction of dinosaurs, which each one has a lot of defects. It has been said ice ages for extinction of mammoths and a lot other theories for other extinctions. My new theory is able to answer all of these questions as a case of a theory and no need to state a different theory for each of these matters. This is my theory's name: "The relation between gravity and evolution" This theory is able to answer many questions about animals and plants and their extinction, which haven't been answered yet.

This theory is organized as cast of several articles that the sun of these articles now available as a book. The title of this book is "The theory of gravity increase". It's ISBN is 8-04-7061-964 in 1999 and have 120 page. It's English translation can be found on following site:

Ramin Amir Mardfar

Updated 10/10/07

Subscribed to Lepidoptera Genetics List Server, please click here

Updated 09/19/07

David: How well does the diet sold by Carolina Biological supply work for rearing Bombyx mori?
Chuck: I have not tried Carolina's diet but have heard that a specific mutation is responsible for acceptance of artificial diets. (Wikipedia's Bombyx mori page, referring to

Marian R. Goldsmith, Toru Shimada, and Hiroaki Abe

Thus, I'm not sure if Carolina's diet will work with all strains or just theirs.

Chuck Kristensen
Spider Pharm Inc.
PO Box 1090
Yarnell, AZ 85362
Telephone: 928-427-6589
Toll-Free (USA): 866-572-0023
Fax: 928-441-1727
Main Site:
Online Store:

David A. Schooley
Dept. of Biochemistry/330
Univ. of Nevada
Reno, NV 89557
Tel: (775) 784-4136; fax (775) 784-1419

*** Announcement: (09/17/07) ***
International Symposium on Insect Midgut Biology
7-11 April 2008, South China Normal University,
Guangzhou, China.

*** Development of an insect-inspired micro air vehicle (poster, 04/13/07) ***

*4th International Conference in Africa for Comparative Physiology & Biochemistry, Maasai Mara National Reserve, Kenya, East Africa, July 19-25: 2008 here.

*Announcement: Insect Physiology Course, University of Massachusetts click here.

*The attached pdf files contain the lecture notes of John G. Stoffolano, Professor of Entomology, University of Massachusetts. He provided Insect Physiology Online with a CD with the understanding that the files could be freely shared with anyone teaching insect physiology. He also gave permission for the files to be posted at IP Online.
Teachers of insect physiology may make free use of these materials. Many if not most of the illustrations were obtained from published sources, many of which can no longer be contacted, but should be considered to be the copyright owners.  Therefore, these materials may not be used for any purpose other than education; they may not be sold or represented as coming from any other source than Professor Stoffolano and his employer, the University of Massachusetts. A courtesy acknowledgement at each use would be professionally expected.
If other uses are contemplated, please check with Professor Stoffolano for permission.

(413) 545-1046
Some of the files are large. Creating pdf files reduced the size somewhat, but it will still take some time to download over slow internet connections.

*Radiation-based technology in crop improvement and pest prevention.

*Molecular biology of epidermal repair, see Integument page.

*Richard Lee's Website


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