"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift
August 14, 2010
August 14 - Fahrenholzia pinnata
Fahrenholzia pinnata is a species of louse that is found sucking blood on kangaroo or jumping mice in the western U.S. The name of this genus is in honor of Heinrich Fahrenholz, who was a German entomologist who studied lice. The pattern that the evolutionary trees of parasites tend to mirror those of their hosts is now called "Fahrenholz's Rule" (though was coined by Eichler, not by Fahrenholz himself). And, lice are almost always the textbook example of this rule. This is because lice spend almost their whole lives on their hosts and become adapted to clinging to their hair to avoid being groomed away. The only time they have an opportunity to transfer from one host to another is via direct contact - which, if you're a rodent, is likely to only occur between members of the same species. This phenomenon is especially true in gophers. See the post from July 16 for more information on gopher lice.