World’s Cutest Parasite

Last week, I invited you to make nominations for the World’s Cutest Parasite. Here’s a compilation of all of the nominations that I received, in order that I received them. Look through, and then vote on your favorite!

(1) Euhaplorchis californiensis

(2) The adult, non-parasitic stages of botflies.


(3) Giardia was nominated several times (HT Dan Metz, Alex Lee, etc.)

(4) Transversotrema was another popular nomination (HT Kevin Lafferty, etc.; photo by RF Hechinger) 


(5) Water mites

(6) Fish tongue isopods



(7) Trypanorhynchs

(8) Here’s something crazy hoisted from an email nomination: “There are rust fungi that cause their host to form flowerlike structures (even with nectar) in order to attract insects by which they are dispersed.” (Photo from Wikipedia)



(9) Naegleria fowleri, the brain-eating amoeba, was a nomination pulled from the comments. I guess if you look very closely, like this, it’s cute?

(10) And finally, my nomination: Trichinella nativa. (Photo from Wikipedia)



So, which of these excellent nominations is the World’s Cutest Parasite?



Nominations for World’s Cutest Parasite

Yesterday morning, I was having one of “those” conversations at the dog park. You know, those conservation where a stranger asks what you study, and you tell them, and they get super grossed out, and you insist that, “No, really, parasites are cute,” and they still don’t believe you, so you use your phone to Google a photo of the World’s Cutest Parasite to prove it to them, and they totally agree that said parasite is pretty stinkin’ cute. I’m not going to tell you which parasite I Googled…yet. First, I want to hear your nominations for the World’s Cutest Parasite. You can send me your nominations on Twitter (@dinoverm #worldscutestparasite) or via email (dinoverm @ I’ll share your nominations next week!

Harry Potter, Cannibalism, and Parasites

I recently read this very interesting blog post about structuring your scientific talks like a Pixar movie. I thought it would be fun to structure some Parasite Ecology blog posts that way, so I’ve tried that for today’s post. I found it easier to model the post after a specific and well-loved story, so I’ve included the model story, too. If you want to follow along, the format is:

Once upon a time there was ___. Every day, ___. One day ___. Because of that, ___. Because of that, ___. Until finally ___.


Once upon a time, there was a pet animal who did not seem to be particularly important to the age-old struggle between good and evil wizards: Scabbers the Rat.

Scabbers was not a glamorous animal, and was perhaps even somewhat revolting or pathetic. But anyone who knew him would have said that he was quite harmless – except, perhaps, for the people who had nearly had their fingers bitten off by Scabbers.

Every day, people went around thinking that Scabbers couldn’t possibly be a significant source of upheaval in the struggle between good and evil wizards.

After all, there were very many animals in the world, but how many had anything to do with important wizarding affairs? Even if you searched very hard, you would only find a few reports of notable pet rats. In fact, it seemed impossible that animals could ever cause much of a stir, because the actions of single animal could never spread among wizards as fast as the ideas or actions of the wizards themselves.

One day, Harry, Ron, and Hermoine found out that their simplifying assumptions about Scabbers had blinded them to a vital detail: Scabbers was actually a key player in the war between good and evil wizards who was hiding in plain sight.

By assuming that Scabbers was an animal, the Hogwarts students had not realized that Scabbers was actually a man. And that man, Peter Pettigrew, had been hiding as a rat for years after betraying The Potters to The Dark Lord.

Because of that, Harry, Ron, and Hermoine became very interested in Scabbers, and scrutinized his history carefully.

They even listened to a supposed murderer who had dragged them into a creepy old shack while he explained all about the role of animals in the struggle between good and evil wizards.

Because of that, Harry, Ron, and Hermoine found out that it is actually quite common and entirely plausible for animals to be key players in the war between good and evil wizards.

A terrifying black dog turned out to be none other than Harry’s Godfather – a very good wizard. And a very scary werewolf was actually Remus Lupin, an excellent professor and a member of the Order of the Pheonix. Even Harry’s own father had been an animagus.

Until finally, Harry, Ron, Hermoine stopped ignoring the potential for animals to be important wizards.

Hermoine even realized that the rotten Daily Prophet reporter, Rita Skeeter, was able to sneak into Hogwarts to find juicy information because she was an unregistered animagus who could turn into a beetle.


Once upon a time, there was an ecological interaction that did not seem to be particularly important to parasite transmission: cannibalism. 

Cannibalism is not glamorous, and is perhaps even somewhat revolting – like when big male polar bears eat little baby polar bears. But as far as parasite transmission is concerned, ecologists generally assume that cannibalism is quite harmless (except, perhaps, for the ecologists who have nearly had their fingers bitten off by cannibals?).

Every day, parasite ecologists went around thinking that cannibalism couldn’t possibly be a significant source of parasite transmission.

After all, cannibalism is very common, but how many parasite systems use cannibalism as a main transmission route? Even when parasite ecologists searched very hard, they only found a few systems where cannibalism was notably important to transmission (Rudolf and Antonovics 2007, Sadeh et al. 2007). In fact, it seemed impossible that cannibalism could be broadly important, because most acts of predation seem to involve one predator eating one prey. In order for a parasite to actually spread in a cannibalistic population, multiple cannibals would need to feed on each victim.

One day, Sadeh et al. (2016) found out that ecologists’ simplifying assumptions about cannibals had blinded them to a vital detail: cannibalism can actually be a key mechanism in parasite transmission that is hiding in plain sight.

By assuming that cannibalism occurs in homogeneous populations, ecologists had missed something important: age or stage structure may mediate the influence of cannibalism on parasite transmission.

Because of that, Sadeh et al. (2016) became very interested in cannibalism, and scrutinized the roles of cannibalism versus other modes of parasite transmission carefully.

In structured populations where older hosts are less susceptible to direct contact parasite transmission, cannibalism on younger hosts by older hosts can be an important mode of transmission, where parasites are moved from susceptible, young hosts who are experience high mortality risk to older hosts who may be more infectious when infected.

Because of that, ecologists found out that it is actually entirely plausible for cannibalism to be important to parasite transmission.

Age- or stage-structured populations are very common, and in many of the known examples of parasite transmission via cannibalism, the host population has age or stage structure. So the conditions required for cannibalism to be an important transmission route may occur in many systems.

Until finally, the person writing this blog post stopped ignoring the potential for cannibalism to be important to parasite transmission.

I can’t speak for everyone, but I think transmission-by-cannibalism is worthy of more attention by parasite ecologists. Because surely there are even more cool examples than the ones we already know about.

Parasites affect ecosystems: the case of the not-so-boring isopods

One day, I’m going to make a list of all of the cool examples of parasites that substantially alter their host’s morphology. Today is not that day. But I do have a really neat example to add to the future list: FASCINATING BORING ISOPODS.

Mangroves are salt-tolerant trees that are important sources of coastal habitat and erosion control. Many species live in, on, and amongst mangrove roots, including a cute little isopod: Sphaeroma terebrans. The mangroves probably don’t think the isopods are all that cute, though, because the isopods bore into mangrove root tips. It has long been hypothesized that this naughty boring behavior might have big effects on root growth, and a recent field experiment confirmed this suspicion. When isopods were excluded from roots using mesh cages, roots grew 2.5-19 times more than they would have without isopod-excluding cages (Davidson et al. 2016). Protected and control roots were also morphologically distinct in metrics other than total length, and you should see Figure 4 in the open access PDF for a nice visual of that.

During the field experiment, 15% of the protected roots became anchored, while 0% of the control roots became anchored. So it looks like isopods really affect the rate of formation of mangrove habitats and the structure of those habitats! That might have far-reaching impacts on the invertebrate and fish communities that rely on the mangroves.

There are many other parasites in many other habitat-forming host species around the world (e.g., corals, Acacia trees, kelp), which makes one wonder how much global habitat distributions and structure are controlled by our Parasite Overlords…or perhaps that’s just me, writing this blog post at 11:50pm.



Davidson, T. M., G. M. Ruiz, and M. E. Torchin. 2016. Boring crustaceans shape the land–sea interface in brackish Caribbean mangroves. Ecosphere 7(8):e01430. 10.1002/ecs2.1430

Everything you thought you knew about keystone sea stars is wrong

…ok, maybe not everything. I’m just getting into the clickbait title fad. But you probably are incorrectly citing Paine (1966), so you’ll be glad you clicked!

Bob Paine, a giant in ecology, recently passed away. He left behind an incredible legacy of ideas and students, and one insanely famous paper: “Food web complexity and species diversity.” If you’re an ecologist, you know that in the experiment described in that paper, Paine removed sea stars from the rocky intertidal and then recorded what happened. In particular, when sea stars were removed, he found that mussels (a favorite delicacy of sea stars) took over more of the primary substrate, crowding out other space-holding species and thus reducing the total number of space-holding species.

According to a recent paper by Lafferty and Suchanek (2016)(PDF link), ecologists usually cite Paine (1966) when they say something like, “predators increase biodiversity by fostering co-existence among competitors.” Most papers never specify which components of biodiversity actually increase when sea stars are present (i.e., primary space-holders). But it turns out that it is important to be specific, because in the rocky intertidal, sea stars actually greatly reduce biodiversity! By eating mussels, sea stars reduce the surface area of an important 3D habitat full of epibionts and parasites and tiny free-living organisms that live among the mussel shells. So, when you cite Paine (1966), you should specify that sea stars increase primary space-holder biodiversity, but reduce total community diversity.

As a side note, my favorite quote from this paper was: “Whelks are like little wolves in slow motion.” Go read it!


Those purple things are mussels. You get the cartoons you pay for on this blog.😛


Lafferty, K.D., and T.H. Suchanek. 2016. Revisiting Paine’s 1966 Sea Star Removal Experiment, the Most-Cited Empirical Article in the American Naturalist. The American Naturalist.

ESA 2016 Parasite Ecology

ESA 2016 was rather small (and hot), but that didn’t stop a lot of excellent parasite ecology talks from happening! I was consistently impressed with the caliber of the talks: very thorough studies, huge datasets, and so much pretty math!

So uh, you might remember how I was supposed to run an unofficial ESA 2016 Parasite Cartoon Contest. Well, I did, but then I left my notes in the hotel, and I can’t remember all of the cartoons without them. Oops! But based on what I do remember, here are my chosen winners:

Honorable Mention:

One morning, I dragged myself out of bed in time to see an 8:00am talk by Alex Strauss. I was not disappointed by his cartoon performance! Consistent with his excellent use of cartoons in 2014 and 2015, he used cartoons to make some very complex hypotheses regarding the dilution effect very clear for the audience. I could even follow his talk before drinking any coffee!


Noam Ross had a few (adorable) cartoons in his talk. But I’m choosing him as the winner not just for his cute bat cartoon, but because all of his slides were so beautiful. You can go look at them here.