This diagram is a contribution to the public domain (provenance details after the "More").
A crabby ending:
The crabs story ran Friday, any concerns about tastelessness to the contrary.
Reader Mrtn (would that be Marten, Maarten, or Martin?):
Kees Moeliker sent me an email afterward to let me know that after the publicity, he has had a phone call from a public health regional office in Haarlem, offering him a sample crab louse.
All's well that ends well, I suppose.
Grobben, Karl - Lehrbuch der Zoologie – N.G. Elwertsche Verlagsbuchhandlung, Marburg, 1917, p. 617 And courtesy of the Rotterdam Natural History Museum.