Monday, July 14, 2008

Flea correspondence

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

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.
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.

John Janovy, Jr.

No comments: