Steenstrup

Steenstrup turned his attention from flukes to the worms that Aristotle had seen living in cysts embedded in pig tongues.

Parasite Rex Carl Zimmer 2009

When Steenstrup pulled the cercariae out of these shelters, he found that they had become flukes.

Parasite Rex Carl Zimmer 2009

Steenstrup scooped up some ditch water, complete with snails and cercariae, and kept it in a warm room.

Parasite Rex Carl Zimmer 2009

Like the flukes Steenstrup had studied, these were shed by snails and swam through water looking for human skin.

Parasite Rex Carl Zimmer 2009

Steenstrup knew that flukes were extraordinary animals, but little more than that.

Parasite Rex Carl Zimmer 2009

The first scientist to realize this was a Danish zoologist, Johann Steenstrup.

Parasite Rex Carl Zimmer 2009

They should have borne in mind the words of Steenstrup, the biologist who had first shown that parasites were unlike anything else on Earth.

Parasite Rex Carl Zimmer 2009

Steenstrup had it right in 1845 when he wrote, “I believe that I have given only the first rough outlines of a province of a great terra incognita which lies unexplored before us and the exploration of which promises a return such as we can at present scarcely appreciate.”

Parasite Rex Carl Zimmer 2009

Looking at all these organisms swimming through the water and through the snails—organisms that in many cases had been given their own Latin species names—Steenstrup made an outrageous suggestion.

Parasite Rex Carl Zimmer 2009

And Steenstrup even found another flukelike creature swimming free, this one not using a missile-shaped tail but instead hundreds of fine hairs that covered its body.

Parasite Rex Carl Zimmer 2009