Rat King Parasite appreciation day

Ever heard of rat kings (Rattenkönig)? It is a real, rare, and disturbing occurrence.

A rat king is a collection of rats whose tails are intertwined and bound together by one of several possible mechanisms, such as entangling material like hair or sticky substances like sap or gum or getting tied together. Historically, this alleged phenomenon is particularly associated with Germany. There are several specimens preserved in museums but very few instances of rat kings have been observed in modern times.

Source

Such  "rosette" ("little rose") shapes of rats are called "rat kings", because the king of rats would sit on top of the knot in the center, being carried around on its throne like a king.

This phenomenon has been reported extensively, so I will not do it. Read this article if you are interested.

The placenta wars

The border zone or transition zone or “ Umlagerungszone” marks the division between the fetal and maternal tissues. As might be expected it is not a sharp line, for it is in truth the fighting line where the conflict between the maternal cells and the invading trophoderm takes place, and it is strewn with such of the dead on both sides as have not already been carried off the field or otherwise disposed of. In the earlier stages there is even more evidence of the deadly nature of the conflict than in the later stages.

Johnstone, R. W. (1914). Contribution to the Study of the Early Human Ovum, page 258.

The placenta appears to be a ruthless parasitic organ existing solely for the maintenance and protection of the fetus, perhaps too often to the disregard of the maternal organism. 

Ernest W. Page. (1939). The relation between hydatid moles, relative ischemia of the gravid uterus, and the placental origin of eclampsia

The placenta is simply a neuroendocrine parasite.

P. J. Lowry (2008). 

Today we take a long, hard look at the human placenta, find out how it is similar to a parasite, a tumor, and a battlefield between the mother and the fetus, and how this makes pregnancy much more risky than it could have been.

To start our journey, think about this question: why is pregnancy so dangerous? The reason is that, in a pregnancy, there are two bodies, instead of one, and they have different interests. They cooperate, but they also fight each other.

The fetus is selfish: it wants itself to be strong. The mother is also selfish: it would rather not devote too much energy to the fetus, because if it does, it would not have enough energy to make another fetus. This is the secret war, taking place on the placenta.

Unless otherwise noted, I'm generally referring to Haig, David, ‘Genetic Conflicts in Human Pregnancy’, (1993).

The ignored placenta  

The placenta... the place where the embryo meets the mother, where the embryo receives the nutrients and the mother receives the waste products. It is a vital organ, but rarely given a thought at all. Think about all the vital organs: brain, heart, lung, stomach, guts, liver, skin, muscles, bones, hand, arm, feet, leg, ovary... each having its own rich implications in culture.

• "Screaming at the top of the lungs"
• "Brain of the team"
• "Right to bear arms"
• "Got guts"
• "Don't drink too much or your liver would complain"
• ...

But what about the ignored organs? The pancreas is all but forgotten, and we can't really blame that. It's small, and has been dismissed as merely a meaty cushion until about 19th century. Even now, its only claim to fame is that it makes insulin, which keeps us from becoming diabetic.

Genitalia, sperm, sex: evolutionary divergence.

Sometimes a good idea just keeps getting rediscovered. The eye has evolved many times independently, and parasitism has evolved for no less than 60 times. This is called convergent evolution. And of course, it has its evil twin... divergent evolution.

Consider this picture below, of the complex shapes of closely related species of Bombus (bumblebees). These species are so similar that the main way to distinguish them is by looking at their penises...

Source: The Evolution of Primary Sexual Characters in Animals, Figure 4.1

Let's read: Parasite of the Day, Part 3

https://dailyparasite.blogspot.com/2020/04/armillifer-armillatus.html
For a multistage parasite, it usually treats its final host well, but the intermediate host unwell. Here, a cheetah ate a snake and got infested by parasites that mistook it for an intermediate host. This resulted in severe infestation.

A male leopard at Kruger National Park, South Africa, which became heavily infected with tongue worm Armillifer armillatus. Researchers found hundreds of A. armillatus larvae throughout the leopard's body cavity, encysted or crawling through the liver, spleen, intestine, and lungs. 

the leopard might have eaten snakes which were infected with female tongue worms that were full of fertilised eggs. After the eggs were liberated from the adult tongue worm's body, they hatched and enter into the next stage of development - the nymphs.

Let's read: Parasite of the Day, Part 2

https://dailyparasite.blogspot.com/2016/12/leucochloridium-paradoxum-revisited.html

Hyperparasites, illustrated by gambling

Consider a gamble house. The ones running the gamble house are parasites upon the gamble addicts.

The moderate gamblers, those who gamble for a little fun, arguably derive more pleasure from the gambling experience than pain of losing money, so the gambling house and the moderate gamblers are mutualistic.

The professional gamblers, the card counters, those who can earn money from the gamble house, are the hyperparasites on the gambling house.

Then there are those hired by the gambling house to catch the card counters. Those are the hyperhyperparasites.

Thus we obtain an ecosystem with:

• Gamble addicts: the hosts.
• Gamble houses: the parasites
• Moderate gamblers: creatures that are mutualistic with the parasites.
• Professional gamblers: the hyperparasites.
• People hired to catch the professional gamblers: the hyperhyperparasites.

Hairworms are awesome

Today's post is ALL about hairworms. I never knew how awesome they are until now!

By default, diagrams are from Thorp and Covich’s Freshwater Invertebrates, Chapter 15 Phylum Nematomorpha.

The lifecycle of hairworms

For hairworms raised in the lab, the entire life cycle takes 4–8 weeks, depending on the species. 

A graphical summary of a typical hairworm lifecycle:

Figure 15.6

1. In water, an egg hatches into a hairworm larva.
2. The larva eats tiny food debris, swimming freely in water.
3. The larva gets eaten by a cricket larva. 
4. The hairworm larva leeches off the cricket and grows up.
5. The cricket is all grown up, and so is the hairworm. The hairworm hears the calling of the water.
6. The hairworm mind controls the cricket to jump into the water. Then in 30-60 seconds, the hairworm emerges and swims away. The cricket might survive this ordeal, feeling a deep emptiness inside.
7. The hairworms mate in water and lays eggs.

They can mind control crickets

This is their source of fame. They do it to make sure they won't dry out after they escape the cricket.

You can think about this in another way: the cricket is actually an intermediate host, and the water is the final host. The hairworm controls the cricket to get willingly eaten by the water, then the hairworms emerge and mate in the body of the water.

The water is an apex predator: it can eat all kinds of species, even humans, by suffocation.