Q31: Pam Pollister writes: What color is the blood of a cockroach?

A: Pam, The long answer: Cockroach blood is not red because they do not use hemoglobin to carry oxygen. In fact their bloodstream is not used to carry oxygen either. They use a system of pipes called tracheae to bring the oxygen and remove carbon dioxide from their tissues.As a result other factors determine the blood color. Male cockroaches have relatively colorless blood. Larval females have colorless blood. Only adult females which are producing eggs have a slightly orange blood because of the protein vitellogenin which is made in the cockroach liver (its fat body) and transported through the blood to the ovary. This protein like chicken yolk is orange because it carries a carotenoid, which is a vitamin A like molecule needed by embryos to develop normally.

The short answer: Cockroach female adult blood is occasionally orange. All other cockroach blood is colorless.¹

Insect blood is actually called hemolymph, or haemolymph for those of you who are not American. But I digress. Let’s back up a little bit.

I have known my friend Steve the longest of any of the friends that I currently have. We haven’t heard each other’s voices in at least 10 years — I’m hoping that he’ll correct me if I’m wrong. The black magic of facebook has kept us connected though.

Our friendship started in high school. Every one of his friends, except for me, were weird and strange and not very popular. He made fun of me, influenced me to attend a university that almost caused me to commit suicide, and gave me shit for talking too much in class. He’s much brighter than I. He’s been on a televised game show and he’s shaken hands with a former prime minister of Canada (Pierre E. Trudeau). He was my lab partner in BIO110.

BIO110 was one of those first-year courses at the University of Toronto that was meant to weed out the people that wanted to go to med school but weren’t academically capable. The sheer volume of information that we had to regurgitate for that course was unbelievable. If I had entertained thoughts about medical school, they were dramatically diminished after I finished this course. The remainder of any potential ideas for medical school were blasted away after organic chemistry in second year. I’m lucky that my life’s path took me to dentistry — which I do immensely enjoy. Hey, if it weren’t for dentistry, I wouldn’t have met that hormonal person who can’t speak english but still likes to comment on my blog. If it weren’t for dentistry, I wouldn’t have met my wife. But I digress yet again.

As I was finishing my degree I really didn’t know what I wanted to spend my life doing so I majored in physiology, got a minor in economics, and took enough courses that I could have received minors in geology and computer science. Computer science is where I met my other buddy Rudy, whose blog you might peruse every so often. We used to play netrek and otherwise waste time that should have been used for studying. Looking back, I was in school for oh so long. My bachelor’s degree took me 5 years, my dental degree 4, my internship 1, my specialisation 2. Good thing Steve and I skipped a year in high school. Actually he might have skipped 2 years, but I can’t remember that far back too well. I’m digressing again.

In BIO110, Steve and I learned about mushrooms, arachnids, women, and cockroaches. Cockroaches are invertebrates. Women are vertebrates and there was this one polish girl that I specifically attended class to check out. She smelled kind of strange, but I really, really liked her–even after I found out that she was engaged.

It is of the experiment in BIO110 in which we learned about cockroach hemolymph (haemolymph if you’re not from the States) that I draw your attention. In my undergraduate university days I became more intimate with a cockroach than I ever thought possible…

Coming Soon: Carcinogenic Concoctions.

1. http://boards.9thwonders.com/lofiversion/index.php/t58015.html [↩]