Flea correspondence

Here is the text of an interesting e-mail I received, along with the reply (sender's name deleted):


xxxx@xxxx.xxx wrote:

Dr. Janovy,

I am trying to find out the answer to a question posed. Does a flea have a heart? Of the anatomy of a flea sites that I went to, none located a heart. What say you? Thank you.

Sincerely,

Ms. S_____

Ms. S___ -

Yes, all arthropods have hearts, although not in the sense that we usually think of as a "heart." Arthropods have an open circulatory system, so that the heart is actually a contractile tube lying in the dorsal haemocoel, above the gut, and [in insects] extending through the thorax and much of the abdomen.

The question of whether fleas have a heart in the metaphorical sense, e.g. whether they feel any sympathy for the dogs, cats, rats, mice, and people they bite, is an open question, but my guess is that the answer is "no." Parasites, if they have any capacity at all for opinions, feelings, or attitudes, probably tend to look at us rather neutrally, as food, rather than victims.

Take care.

JJ
John Janovy, Jr.
http://bsweb.unl.edu/labs/janovy

Terry and Scott -

I'm still trying to figure out how to get the figures up; it will (WILL!) happen, I promise! - JJ

Let's Talk Parasites

Among all the conversations I've had with various people, perhaps the most interesting ones are about parasites--real parasites, social parasites, imaginary parasites, metaphorical parasites, and memes that act like parasites. So feel free to join this conversation!!