"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

January 14, 2011

Arthurhumesia canadiensis

Parasites come in all kinds of bizarre shapes and you don't get much more bizarre than today's parasite - Arthurhumesia canadiensis. This species is a parasitic copepod that lives inside the intestine of the compound ascidian (sea squirt) Aplidium solidum. The diagram shows a female specimen, with a pair of lobe-like egg sacs attached. And if you are wondering "what's the weird little blob the arrow is pointing at?", well that's the male copepod. This weird little crustacean is named after Arthur Humes - a very prolific taxonomist. Over the course of 60 years, he was responsible for describing over 700 new species of parasitic copepods. So it's only right that a copepod named after him would appear on a blog which is about parasite biodiversity!

Bresciani, J. and López-González, P.J. 2001. Arthurhumesia canadiensis, new genus and species of a highly transformed parasitic copepod (Crustacea) associated with an ascidian from British Columbia. Journal of Crustacean Biology 21(1): 90-95.

Contributed by Tommy Leung.


  1. I just found your blog tonight. I like the idea of featuring a parasite each day.

  2. Thanks, Tracy - we did a parasite every day during 2010, to celebrate the International Year of Biodiversity. This year, we are posting just from time to time.

  3. I found your blog a while ago, and have loved it since. I've just learned how to follow blogs, so here I am. Good work on shedding some light on a neglected science. WOO SCIENCE!

  4. Parasites? A topic least talked upon. Thanks for shedding some light on the same. Bookmarked your blog to read more from you.