Relevant notes and citations provided to TED by Ed Yong.
Sadly and unavoidably, that’s the wrong species of tapeworm in the picture. It’s a dog tapeworm; I couldn’t find a picture of the exact species that targets Artemia.
Nicolas O. Rode et al., "Why join groups? Lessons from parasite-manipulated Artemia," Ecology Letters, April 2013
Here’s the full story about the tapeworm, Artemia and the greater flamingo, and above is the original paper. While I’ve focused on the tapeworm for the sake of simplicity, a second parasite — a microsporidian fungus — is also involved in making the shrimps shoal.
A few people asked me after the talk if other animal groups might be caused by parasites. There’s at least one other similar example: Sticklebacks are more likely to shoal if they are infected with a microsporidian fungus, and the infected fish are more likely to take up pole positions.
David Biron et al., "'Suicide' of crickets harbouring hairworms: A proteomics investigation," Insect Molecular Biology, December 2006
A lot of the key research on Gordian worms and crickets was done by Frédéric Thomas and David Biron. Here’s the paper in which they discovered the proteins that drive the crickets to suicide.
Gordian worms are also called horsehair worms or nematomorphs. They belong to their own phylum, which contains a few hundred species. All of them are parasites.
I’ve written about several other manipulative parasites that I didn’t get a chance to cover in the talk, including a worm that has inspired medical tape, a wasp that turns ladybirds into bodyguards, and a liquefying virus that makes caterpillars climb. Other favorites include the worm that turns ants into berries, the wasp that turns spiders into construction workers, the parasitic barnacle that turns crabs into inadvertent nurseries, the killer fungus that zombifies ants and the killer fungus that targets the killer fungus that zombifies ants.
Wanda Wesolowska and Tomas Wesolowski, "Do Leucochloridium sporocysts manipulate the behaviour of their snail hosts?," Journal of Zoology, March 2014
This is the first example of parasitic manipulation that crossed my path — the flatworm Leucochloridium, which turns snails into throbbing billboards for birds. The parasite’s behavior was first described in 1835 and was featured in David Attenborough’s Trials of Life many years ago. But astonishingly, scientists only conclusively proved that it really does manipulate its host in late 2013 — a good reminder that scientific hypotheses need to be checked before they enter the textbooks.
Amir H. Grosman et al., "Parasitoid increases survival of its pupae by inducing hosts to fight predators," PLOS ONE, June 4, 2008
The caterpillar is Thyrinteina leucocerae and its parasite is a Glyptapanteles wasp. Here’s their story, as discovered by Amir Grosman; the open-access paper that originally described it is above.
Armand M. Kuris et al., "Ecosystem energetic implications of parasite and free-living biomass in three estuaries," Nature, July 2008
Takuya Sato et al., "Nematomorph parasites drive energy flow through a riparian ecosystem," Ecology, January 2011
Here’s Takuya Sato’s study on Gordian worms, crickets and (endangered) trout. Note: I mispronounced Sato's name as Takuya Soto. I sincerely regret the error.
Parasites are so common and important that some parasites specialize in parasitizing other parasites.
Carl Zimmer: Parasite tales: The jewel wasp's zombie slave, TEDYouth 2012
Wendy Marie Ingram et al., "Mice infected with low-virulence strains of Toxoplasma gondii lose their innate aversion to cat urine, even after extensive parasite clearance," arXiv, July 2013
Jaroslav Flegr et al., "Increased incidence of traffic accidents in Toxoplasma-infected military drivers and protective effect RhD molecule revealed by a large-scale prospective cohort study," BMC Infectious Diseases, May 2009
Here’s a study linking Toxo to car accidents, and an Atlantic profile of Jaroslav Flegr, who has done much of the work on Toxo and personality traits.
After the talk, lots of people asked if Toxo explains the "crazy cat lady" idea. It's not totally implausible; unlike mice and rats, we don't have any innate fear of cats for Toxo to tweak, but during our evolutionary past, our ancestors probably did encounter large predatory cats. Then again, there is no actual evidence to support the idea that Toxo could affect our attitude towards cats. And the main route through which humans are infected by Toxo is contaminated meat, not cat ownership.
Charles Darwin, On the Origin of Species, Emporia Books, 2011
The full Darwin quote, from On the Origin of Species: "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."