User:RandomCitizen27/Apparent death

Lead
Apparent death, colloquially known as playing dead, feigning death, or playing possum, is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a wide range of animals from insects and crustaceans to mammals, birds, reptiles, amphibians, and fish. Apparent death is also referred to as thanatosis, animal hypnosis, immobilization catatonia, or tonic immobility, the latter of which is preferred in the scientific literature on the subject.

Apparent death is a form of animal deception considered to be an anti-predator strategy, but it can also be used as a form of aggressive mimicry. When induced by humans, the state is sometimes colloquially called animal hypnosis. The earliest written record of "animal hypnosis" dates back to the year 1646 in a report by Athanasius Kircher, in which he subdued chickens.

Tonic immobility
I will keep the introduction section that is already in the paper but add that:

"Tonic immobility is preferred in the literature because it has neutral connotations compared to 'thanatosis' which has a strong association with death. "

I will also add that "Tonic immobility (also known as the act of feigning death, or exhibiting thanatosis) is most generally used as an anti-predator response, but can also be used by predators to attract prey, or to facilitate reproduction."

Tonic immobility vs. freezing
Tonic immobility (and therefore "feigning death") is different from the "freezing" response in animals. A deer in headlights and a possum "playing dead" are common examples of an animal freezing and playing dead, respectively. Freezing occurs early during a predator-prey interaction when the prey detects and identifies the threat, but the predator has not yet seen the prey. Because freezing occurs before detection and is used to better camouflage the prey and prevent the predator from attacking, it is considered a primary defense mechanism.

Tonic immobility occurs after the predator has detected and or made contact with the prey, and is likely used to prevent further attack by the predator or consumption of the prey. Because tonic immobility occurs so late in the predator attack sequence, it is considered a secondary defense mechanism and is therefore distinct from freezing. Although freezing animals become rigid, they often stay upright and do not change their posture while frozen whereas during tonic immobility, animals often become rigid and change their posture.

Freezing behavior and and tonic immobility are similar in that both may induce bradycardia (slowing of the heart rate), but the freezing response may instead be accompanied by rapid or increased breathing rate, increased heart rate, increased blood pressure and inhibition of digestion, depending on whether the sympathetic or parasympathetic nervous system is engaged. In contrast, along with bradycardia, vertebrates in tonic immobility often reduce their breathing rate or protrude their tongue, further distinguishing this behavior from the freezing response.

Tonic immobility in invertebrates
Tonic immobility is widespread throughout phylum Arthropoda and has been demonstrated to occur in beetles, moths, mantids, cicadas, crickets, spiders, wasps, bees, and ants.

Tonic immobility in vertebrates
Tonic immobility has been observed in a large number of vertebrate taxa, including mammals, birds, amphibians, and reptiles.

Tonic immobility in ducks
Tonic immobility has been observed in several species of ducks as an effective anti-predatory response. A study by Sargeant and Eberhardt (1975) determined that ducks who feigned death had a better chance at surviving a fox attack than those who resisted and struggled. Despite being immobile the ducks remained conscious and were aware of opportunities for escape. Although the researchers concluded that tonic immobility was an effective anti-predator response, they conceded that it would not be useful against predators that kill or fatally injure prey immediately after capture.

Tonic immobility in chickens
Tonic immobility can be induced in chickens, but the behavior is more colloquially referred to as hypnosis. See chicken hypnotism for more information on tonic immobility in chickens.

Tonic immobility can be induced in chickens though several means, including by gently restraining them on their side, stomach, or back for a short period of time, or by using chalk to draw a line on the ground away from the chicken's beak while restraining them with their head down. Chickens have been used in several studies to elucidate the genetic basis of tonic immobility. While early studies focused on determining whether tonic immobility was influenced by genetics, a study in 2019 identified five genes that potentially control tonic immobility in white leghorn chickens and red junglefowl.

Tonic immobility in rabbits
Tonic immobility occurs in both domestic and wild species of rabbit and can be induced by placing and restraining the animal for a short period of time. As in other prey animals, tonic immobility is considered to be an antipredator behavior in rabbits. Studies on tonic immobility in rabbits focus on the European rabbit Oryctolagus cuniculus, but other species of rabbit have been studied. A laboratory experiment by Ewell, Cullen, and Woodruff (1981) provided support to the hypothesis that European rabbits use tonic immobility as an anti-predator response. The study found that how quickly the rabbits "righted" themselves (i.e. how quickly they came out of tonic immobility) depended on how far a predator was away from the rabbit, and how close the rabbit was to their home cage. Rabbits that were closer to their home cage righted themselves more quickly than those that were farther from their home cage. Conversely, when predators were closer to the rabbits, they took longer to right themselves. These results were consistent with those found in studies on chickens, lizards, and blue crabs at the time, and provided support that rabbits use tonic immobility as an antipredator response.

A more recent study on European rabbits monitored their heart rate during tonic immobility and found a several physiological changes to the cardiovascular system during this state, including a decrease in heart rate.

What I will put in the talk page once I delete the "in rabbits" paragraph and replace it with new information.

I removed the disputed section and replaced it with new (hopefully less contentious) material for several reasons that I will detail in this paragraph. The resource they sited only led me to conference proceedings, not a peer reviewed paper where the researchers scientifically reported their methods, data, results, conclusions, etc.. The article was about how TI in rabbits induces a stress response, which makes sense when you remember that TI is usually induced because of attack by predators. The article was also very neutral in its wording, unlike whoever wrote the rabbit paragraph. I think whoever wrote this section in the wiki article was referring more to the consequences of the work (e.g., the proceedings were supposedly cited to support the notion that rabbits "hate what they appear to enjoy"), rather than what the authors actually concluded and were trying to report in their work, so what was written wasn't an accurate (or neutral) interpretation of the study. The proceedings said nothing about rabbits "hating" being put in tonic immobility, just that it causes a stress response in them. Furthermore, I couldn't locate any articles (scientific or otherwise) that cited this article to advance or perPETuate (haha) the idea that rabbits "hate what they appear to enjoy." The wiki paragraph also did not provide a citation for rabbits "sometimes sleeping on their backs" but uses that statement as a basis for refuting the meaning that they inferred from this article. Finally, language such as "a single study in rabbits" and "failed to explore" is not neutral which violates the Wikipedia rules for articles. That combined with the rest of the paragraph that extrapolates the meaning of the article, I decided to remove this paragraph and start anew.

Tonic immobility in amphibians and reptiles
Tonic immobility can be found in several families of anurans (frogs and toads). In anurans, tonic immobility is demonstrated by most often with open eyes and the limbs sprawled and easy to move, but some species keep their eyes closed. Some species also protrude their tongue.

Tonic immobility has also been observed in several species of lizards and snakes. The most common example of tonic immobility in snakes is the American hog-nose snake, but it has also been observed in grass snakes.

General reconstructions
I will get rid of the "thanatosis" subsection because thanatosis and tonic immobility are the exact same thing. I will keep the introduction to tonic immobility and get rid of the thanatosis introduction.

I will place the "for reproduction, for defense," and "for predation" sections directly below the introductory paragraph of the tonic immobility subsection. This is so that the more broad categories (for predation, reproduction and defense" go before the more specific examples of tonic immobility in specific groups of animals.

I will also put whatever is in the current tonic immobility section into a new subsection called "examples of tonic immobility in animals."

I am removing the image of the common swift because I cannot find any reputable literature confirming that common swifts exhibit thanatosis.

Article Outline (peer reviewers: please ignore this section! It was my outline :)
=== Note: things in bold that aren't a section/subsection heading are just main objectives: short summaries of what I will do. They're kind of like a goal on a checklist, just integrated into a paragraph. ===

Lead
Currently this lead section is misLEADing. It doesn't do a very good job of distinguishing between thanatosis, tonic immobility, and apparent death. I plan to make the distinctions between them more clear by explicitly stating the differences between them. (nevermind, they're all the same thing so I'll re-write it so that it makes it obvious that they are all synonyms. The current lead paragraph also doesn't do a great job of introducing everything that's in the article, so I will address this. This will include adding how both thanatosis and tonic immobility are exhibited in several animals from invertebrates to vertebrates and ways it is used (for example for defense, predation, reproduction, etc.). This will have to be done after the article is done, of course!

Someone in the talk page (in 2020! See bottom-most reply of "Cannot merge") put it succinctly by saying that the lead introduces tonic immobility and thanatosis as synonyms, but in reality it doesn't seem like they are!! Thank you random stranger for validating my thoughts.

Article body
As someone pointed out in the talk page in 2021 (see "purpose and intent") there are some sections in the article where intention is assigned to the behavior, such as "Cichlids of the genus Nimbochromis express thanatosis as a form of aggressive mimicry, playing dead to attract prey." Another example is "the Virginia opossum, which is famous for pretending to be dead when threatened ." The connotation of the word "pretending" or "playing dead" implies the animal has conscious intent behind its actions, whereas in reality (as the other user points out) these are instincts that can have functions and potential effects (such as obtaining food), but we cant infer the purpose of the behavior because it is an instinct. I will try to address the points that the other user brought up (the sentences quoted above) and look for similar issues as well. I will need to be careful to not assign intent while writing this article but will take practice (and probably some help form the prof/TA's. What are some alternatives to "playing dead" or "pretending?" There must be a better way than just putting these words into quotations.

Tonic immobility
Flesh out the sections on tonic immobility in chickens and ducks by locating sources and adding information on both. I may group these into a "tonic immobility in birds" section just to increase organization of the article. If I can find examples of tonic immobility in other birds I'll add these as well.

Look into the example in the photo of a "black house ant attacking a green headed ant which has gone into tonic immobility." Is the ant really in tonic immobility, or is it feigning death? (i.e. was its state induced by an external threat or was it not?). If it IS in tonic immobility then I will generate and add it into a section on tonic immobility in invertebrates. Likewise, I will look into more examples of tonic immobility invertebrates as well.

Add section on tonic immobility in rodents. Later the article mentions how tonic immobility has been used as a scientific tool in mice, gerbils, guinea pigs, and rats, but doesn't offer any explanations or elaboration. I will add this and place it into its own section on rodents, and add the section that is already written on tonic immobility in rabbits as well.

I will try my best to address the neutrality of the "In rabbits" section.

I will likely add a sub section on tonic immobility in pigs and any other animals I come across.

I am hesitant to add or change anything in the "in humans" section. I would have to be very careful about how I write such a section and I really don't feel comfortable reading articles relating to traumatic events.

Compared to thanatosis, I think it will be difficult to find research on "what function does tonic immobility serve" or what is the advantage to it or why it has evolved, but I will try to look into these questions (or others like them) so that this section isn't just "what animals exhibit tonic immobility!?" ALTHOUGH, I could try to find research on why tonic immobility occurs, i.e. what are the mechanisms behind why animals stop moving. I feel like there will be research out there on this.

Thanatosis
Will likely rearrange the article so this section is before tonic immobility because it is closer to what feigning death actually is.

For my own curiosity (I'm really interested in genetics), I will search for studies on the genes for thanatosis in animals. If some exist I will summarize their findings and add them to the article under a new subsection.

I could maybe research if thanatosis is adaptive? Or maybe see if there are any times where it is mal adaptive? (such as the opossums becoming road kill themselves in one of the paragraphs). I think this would be interesting.

Defense subsection
I will break this into "vertebrates" and "invertebrates," as there are several examples of this behavior in each. For invertebrates, I will elaborate more on the wasp and cricket examples given in the article (Nasonia vitripennis and Gryllus bimaculatus, respectively). I will also look to see if there are more examples of this in invertebrates!

I can add the "fire-bellied toad" as an example of using thanatosis for defense. This frog has a very red underbelly, so when it plays dead it goes belly up, showing predators that it has toxins in its skin.

Reproduction subsection
Add more examples for use of thanatosis for reproduction!

Predation subsection
Add hyperlink to the aggressive mimicry page.

Add more examples for use of thanatosis for predation. Also elaborate more on the "similar strategy" mentioned in other cichlid fish ("African cichlid Lamprologus lemairii from Lake Tanganyika and in the Central American yellowjacket cichlid Parachromis friedrichsthalii. ") Could honestly make an entire subsection in predation dedicated to cichlid fish at that point. Also consider looking into if its seen in other, non-cichlid fish.

Check if other animals use color changing during thanatosis as well or if it's just those Nimbochromis cichlid fish. Speaking of this, I should stay on the lookout for the different strategies animals use during thanatosis to portray death, like for example how the hog-nosed snake releases a foul smelling ooze compared to the possum that just looks dead.

The sentence "'Playing possum' can also mean simply pretending to be injured, unconscious, asleep, or otherwise vulnerable, often to lure an opponent into a vulnerable position him or herself " should probably be moved from the defense subsection into the predation subsection. If I can find examples of these it will tie in nicely to the examples of predation.

General notes
If I can, I will add or rearrange the photos or edit their descriptions as necessary to make them more relevant to what each section is talking about. For example, it is unclear whether "Burmeister's leaf frog" is exhibiting thanatosis or tonic immobility; same with the photo of the young common swift. I will add text about the animal into the main body of the article where appropriate e.g. write a paragraph on tonic immobility in the common swift in the tonic immobility section. I will also do this with the brown widow spider because there is a photo of it in thanatosis but no written explanation.

The advice in the article on brown bears is questionable and I'll probably end up removing it or changing its wording because I'm not sure if it counts as thanatosis, or if the actions are meant to resemble thanatosis.

Are fainting goats an example of thanatosis? I don't think I don't think they use it as a defense mechanism. The fainting kind of just happens because of their physiology. I'll look into this.

"Tickling trout" may be an example of tonic immobility. More of a behavior done by humans to trout than a behavior of trout themselves, but isn't this true of all tonic immobility cases? I'll investigate this and probably ask the prof if it would really count.

Just a related question that I'd like to look in to: What's the difference between feigning death and freezing in fear? (like deer in headlights?). Freezing in headlights doesn't really look like death. I could add the distinction into the article! (I don't really know if it's a necessary distinction though).

I think I'd like to change the name of the page for the album "Playing possum" to "Playing Possum (Album)" because its somewhat confusing that "playing possum" can take you here or to a music album, but I would need to go to the playing possum (album) page and mention it on the talk page, because I feel like that's a major change.

Can add a section on the challenges of studying thanatosis in animals.