2. her grandfather, whom she called “Pop” (A. popi)
3. James Rodman at the National Science Foundation (A. rodmani)
4. Jim Romanow, who took care of the microscopes Fyler used (A. romanowi).
I’m still grateful for Fyler’s gesture, and I still can’t help but feel some vaguely paternal pleasure at seeing how A. zimmeri helps scientists learn a little bit more about the diversity of life and how that diversity evolved. Fyler and her colleagues compared A. zimmeri’s DNA to other Acanthobothrium species and discovered something interesting: the five Acanthobothrium species that they found dwelling in the single whip ray were not closely related to one another. Instead, their closest relatives live in other species of whip rays. Somehow their ancestors must have made the leap from one host to another, and somehow they must have made a place for themselves in the crowded ecosystem that is the inside of a whip ray’s gut.
For now, that leap remains almost entirely a mystery. Scientists have no idea what sort of life cycle A. zimmeri and its relatives have—what happens to the eggs that the tapeworms release from the whip rays, or what other hosts they may have to invade first before finally ending up in another whip ray. Like its whip ray host, A. zimmeri’s intermediate hosts probably have yet to get names of their own.
I hope some day scientists do figure out my namesake’s life cycle, but I also worry that their time may be running out. Whip rays, like many other rays and sharks, are in serious trouble these days thanks to reckless overfishing. And whenever one species becomes extinct, it can take other species with it. Switching host species is an exquisitely rare event, and so it’s likely that A. zimmeri can only live in one species of whip ray. When its host goes, it may disappear as well.
Now, more than ever, I feel my existence intertwined with that of parasites. Long after I’m dead, I hope that there will be whip rays swimming the Arafura Sea infested with tapeworms that bear my name.
Glossary
Antibody: A protein created by the immune system that can attach to antigens and neutralize them.
Antigen: A foreign substance that stimulates an immune response.
B celclass="underline" A type of immune cell that produces antibodies.
Blood fluke: One of several species of flukes that live in the bloodstream of vertebrates. The best studied are schistosomes, such as Schistosoma mansoni, which cause the disease schistisomiasis.
Chloroplast: A compartment in plants and algae where photosynthesis takes place. Originated as a free-living bacteria, which was engulfed by a eukaryote.
Complement: Blood-borne molecules that attack antigens, either on their own or in conjunction with antibodies.
Copepod: an aquatic crustacean that serves as an intermediate host to many parasites.
Cotesia congregata: A species of parasitic wasp that makes the tobacco hornworm its host.
Elephantiasis: A disease caused by filarial worms. The worms reside in the lymph channels, and the reaction of the immune system creates obstructions that trap lymph fluid in limbs or genitalia.
Flukes: Parasitic flatworms belonging to the class Trematoda.
Guinea worm: A parasitic nematode that lives in the abdomen of humans. After mating, the female emerges from her host’s leg and releases larvae, which take up residence in a copepod.
Hookworm: A parasitic nematode that lives in the soil as a larva and as an adult in the human intestines. Consumes blood and causes anemia.
Macrophage: An immune cell that kills foreign organisms either by engulfing them or by releasing poisons.
Malaria: A disease characterized by high fever, caused by the protozoan Plasmodium.
Mast celclass="underline" Immune cell in linings of the intestines and nose; the cell can suddenly trigger allergic reactions.
Plasmodium: The protozoan that causes malaria.
River blindness: A disease caused by Onchocerca volvulus, a parasitic nematode. Blindness is caused by scarring triggered as the parasite crawls across the eyes.
Sacculina: A parasitic barnacle that lives in crabs.
Schistosomiasis: Also known as bilharzia. Disease caused by schistosomes, blood flukes that live in snails and humans. Its most serious symptom is liver damage caused by the immune system’s reaction to schistosome eggs.
Sleeping sickness: Disease caused by the protozoan Trypanosoma brucei, and transmitted by the tsetse fly. Causes disorientation and coma. Fatal if not treated.
T celclass="underline" Immune cell that can recognize specific antigens. Killer T cells destroy cells infected with viruses and other pathogens. Inflammatory T cells organize attacks by macrophages. Helper T cells work with B cells to produce antibodies.
Toxoplasma gondii: Protozoan that normally makes cats and their prey its hosts. Usually harmless in humans, except for pregnant women and people with compromised immune systems.
Trichinella: Parasitic nematode that lives in muscle cells.
Trypanosomes: Parasitic protozoa belonging to the genus Trypanosoma. Cause sleeping sickness (T. brucei), Chagas disease (T. cruzi), and other diseases.
Notes
Prologue: A Vein Is a River
xiv “Trypanosoma brucei has many enchanting features …”: Borst et al., 1997, p. 121.
xvi Over 1.4 billion people carry the snakelike roundworm: These statistics come from Crompton, 1999.
1. Nature’s Criminals
1 “Nature is not without a parallel …”: Brown, 1898.
2 Eventually the parasite became a standard character: Damon, 1997.
2 Aristotle, for instance, recognized creatures: Grove, 1990.
2 two serpents wound around a staff: Roberts and Janovy, 2000.
3 “The substance in question cannot be a worm …”: Quoted in Grove, 1990, p. 121.
4 “Some shoot forth horns …”: Quoted in Wilson, 1995, p. 160.
5 The mysterious nature of parasites: See Farley, 1972.
6 “arches over them like a small, closely shut watch glass.”: Quoted from Steenstrup 1845, pp. 57–58.
7 “An animal bears young …”: Quoted from Steenstrup, 1845, p. 132.
8 “It would be contrary to the wise arrangement of Nature …”: Quoted in Farley, 1972, p.120. For more details on the discovery of tapeworm life cycles, see also Grove, 1990, and Foster, 1965.
11 By 1900, bacteria were rarely called parasites anymore: Worboys, 1996.
11 When Leeuwenhoek had looked at his own feces: Roberts and Janovy, 2000.
13 When Napoleon took his army to Egypt: Nelson, 1990.
14 in the words of one scientist at the time, “medical zoology.”: Worboys, 1983.
14 “It is derogatory that the Creator …”: Quoted in Desmond and Moore, 1991, p. 293.
15 “I cannot persuade myself that a beneficent and omnipotent God …”: Quoted in Desmond and Moore, 1991, p. 479.
15 To their mind, orthogenesis brought a purpose: Bowler, 1983.