Season 1: Episode 3- The Quiets

Film: A Quiet Place [2018]
Production Company: Platinum Dunes
Distributed By: Paramount Pictures
Monster: The Quiets
Featuring: Sam, Adam, David
Rating: Mature (for some offensive language and adult themes)

Episode 3- The Quiets Fact Sheet



Quiets- Physio 2
Paramount Pictures, 2018


Near the end of the film, one of the Quiets is seen on top of a midsize truck, allowing us to estimate the size. An average truck is around 17 feet long, and The Quiet looks to be approximately ½ the length of the truck when stretched out, therefore:

  • Final Height= 9 feet or 2.7 metres

The closest animal that resembles the body plan of The Quiet in nature appears to be a bat, without the tissue on the wings. I decided to scale up a vampire and ghost bat to try and get an average estimate of mass.  I also scaled up a rhino and a crustacean, in line with later discussions about animals with thick/bullet resilient skin. Like previous discussions, I will be using the square-cube law:

  • Average Common Vampire Bat Mass= 30 grams or 0.03 kg
    Average Common Vampire Bat Height= 9 cm or 0.09 metres
    Common Vampire Bat Ratio= 30 times bigger, Mass= (30^3)(0.03)= 810 kg
  • Average Ghost Bat Mass= 150 grams or 0.15 kg
    Average Ghost Bat Height= 12 cm or 0.12 m
    Ghost Bat Ratio= 22 times bigger, Mass= (22^3)(0.15 kg)= 1597 kg
  • Average White Rhino Mass= 2400 kg
    Average White Rhino Length= 4 metres
    White Rhino Ratio= 0.7 times bigger, Mass= (0.7^3)(2400 kg)= 823 kg
  • Average Dungeness Crab Mass= 2.5 pounds or 1.1 kg
    Average Dungeness Crab Length= 6 inches or 0.15 metres
    Dungeness Crab Ratio= 18 times smaller, Mass= (18^3)(1.1 kg)= 6415 kg

Total Mass- Final Thoughts
There is a wide variation in the possible weight predictions. The Quiets will most likely have an exoskeleton that will give them weight similar to what is seen in a crab. However, if The Quiets weighed as much as the Dungeness Crab prediction they would crush the truck by walking on it (average force to crush a car is 6,000 kg). Furthermore, if there are too heavy they would not be able to move at the speeds seen in the film. Based on this information, I was more comfortable placing The Quiets’ weight between that of an enlarged Ghost Bat or reduced Rhino (~1000 kg).


We can use the Ghost Bat as an example species whose BMR we can scale up. This is because the Ghost Bat eats small mice and other live animals. It also sleeps for long periods of the day, like what we assumed the Quiets do in the Ecology section.

  • Ghost Bat Average BMR= 13 kJ/day
    BMR = (a)M^⅔
    13 kcal/day= (a)(0.15 kg^⅔)
    a= 46
    Predicted Quiet BMR= (46)(1000^⅔)= 4600 kcal/day

Final Thoughts- Metabolic Rate
It is predicted that The Quiets BMR would be around 4600 kcal/day. Based on their activity level within the film, I am also comfortable saying that their DER would be the same as long periods of their day seem to be at rest or on patrol. Only exerting themselves for the kill. However, if their activity is greater than what is seen outside of the farm, it could increase up to ~9000 kcal/day.


In order for The Quiets to survive travel through space they would need to adopt strategies similar to Tardigrades or Brine Shrimp. In the event of a planetary explosion in another solar system, it would take tens of thousands of years for any form of meteor to reach earth. No intact organism could survive the destruction of their planet and travel through space for thousands of years. However, it might be possible for dehydrated eggs to make the journey.

Brine shrimp eggs are one of the most resistant organisms on the planet. They are laid by Brine Shrimp and dehydrated during droughts or other extreme environmental activities. Current research indicates that in their dehydrated state they can be rehydrated after 10,000 years and still hatch and their outer limit still remains unknown. When dehydrated they can be set on fire, dissolved in alcohol, deprived of oxygen, zapped with UV radiation, boiled, and frozen. They can survive in the vacuum of space or at pressures comparable to the bottom of the ocean.

Final Thoughts- Hibernation
In order for the Quiets to survive the destruction of their planet and travel through space to earth they will need to lay eggs. As we will discuss in the ecology section, we theorize that the Quiets evolved in caves on a planet with extreme surface temperatures. Like the Brine shrimp, we expect that they will lay their eggs on their homeplanet and dehydrate them due to extreme environmental circumstances. These eggs would be the only thing capable of surviving the trip through space and through the atmosphere. Upon arrival through the atmosphere, contact with water would allow the eggs to hatch and for the Quiets to develop on Earth. However, it should be noted that only a limited number of eggs will hatch to produce viable, non-deformed offspring.


It is mentioned in multiple aspects of the film that the Quiets are nearly indestructible. Reports in newspaper clippings within the film indicate that the Quiets are able to withstand gunfire and assaults by the army. In order to have some of these incredible resistances, they will need to posses a few physiological adaptations. The obvious answer to this problem is to have their tissue composed of a structure not seen on earth. However, as the organisms are surviving on earth and appear to be able to build themselves out of substances found on our planet they will likely have mechanisms similar to terrestrial organisms.

Tough Earth Organisms
No terrestrial animals are bulletproof. For example, a rhinos skin is around 1.5 – 5 centimetres thick and is formed from layers of collagen (the main protein of connective tissue in animals and the most abundant protein in mammals), positioned in a lattice structure (crisscrossed framework). This gives the rhino the ability to resist small calibre fire if the bullet trajectory is correct, but they are not bullet resilient not bulletproof.

Based on the observation in the film, I think that the Quiets would likely possess a hard exoskeleton like a crab. Crabs build their shell asa a natural composite consisting of highly mineralized chitin–protein fibers arranged in a twisted plywood or Bouligand pattern. Their claws are 3-4 times harder than the rest of their shell or those of their walking legs. The arthropod exoskeleton is multifunctional: it supports the body, resists mechanical loads, and provides environmental protection and resistance to dehydration.

Final Thoughts- Integument
The Quiets would likely possess an exoskeleton. This would allow for control of the interconnected plates that seem to open and close throughout the film. It would also give a degree of protection against gunfire and other attacks. It is possible that they would build their carapace in a way that is not seen in other organisms to protect themselves from more aggressive military attacks. However, it is more likely that they will not be completely bullet proof. The weight of the plates will need to be kept to a minimum to allow for quick movement and an endoskeleton the quiet would also need to possess an complex musculoskeletal system to open and close the plates.


Animals with exoskeletons attach their muscle system directly to outer shells and use contractions to move these plates in a similar fashion to how me move our internal skeleton (endoskeleton). In order for the Quiets to open and close their face plates for hearing and exposure of their underlying tissues they would need to posses a complex system of muscles. However, because of their size, the Quiets would most likely be required to also possess an internal or endoskeleton to support their weight and rapid movement on land.


The Quiets would likely have an internal endoskeleton for support along with an exoskeleton for protection. In order to keep their weight down and allow for faster movement they might need to employ techniques similar to bats. Although their bones would remain vascularized, they would be reduced in size. However, their density and strength would still remain relatively the same.


The Quiets would employ teeth similar to what is seen in other top level predators. The teeth in the film are sharp and completely carnivorous. They might exist in rows and fall out similar to sharks.


They will need a heart in order to move blood through their system. Unlike smaller arthropods, they will not be able to use spiracles to directly bathe their tissues in oxygen. Other crustaceans traditionally use a hemolymph solution to oxygenate their tissues, but as this substance carries less oxygen, it would not be sufficient for The Quiets high metabolic needs on land. They would likely need to use a substance similar to hemoglobin. Terrestrial crabs do have a heart and a modified cardiovascular system that works in a similar fashion to what is seen in mammals.


Within the film, we see that The Quiets are breathing, and we hear them moving air in and out of their thorax. However, we don’t see obvious signs of respiration like their chest moving up and down. This fits with them possessing an exoskeleton like a crab.

Crabs have respiratory specializations that allow for gas exchange using a modified internal gill structure. They also have ventilatory mechanisms that permit effective pumping of air into the thorax for the purposes of exchange in a method that is similar to continuously breathing. This exchange takes place within brachial chambers, and pumping occurs using an organ called a scaphognathites. The lining of these structures and the modified chambers are usually kept moist, are highly convoluted, and have mechanisms to filter air coming in.

Final Decisions- Respiratory
The Quiets will likely have modifications similar to a crab. Air will be pulled continuously into their a brachial chamber within their carapace using some form of pumping organs. Lungs would work but using them within an animals with an exoskeleton would be physiologically very difficult.


We know that the Quiets are blind, and appear not to have any developed form of smell. The do have an incredible sense of hearing though. Throughout the film we hear a high pitch clicking noise when the Quiets are near. I suspect that this sound is the Quiets performing echolocation. Bats have an ultrasonic hearing range from 20 to 200 kilohertz. Using their larynx and nostrils they generate a series of sounds within this frequency range. Humans can only hear the noises generate at the lower end (~20 kilohertz). The sounds generated by the bat bounce off objects in their environment and return to them where they are interpreted. In order to avoid deafening themselves, the bats middle ear contracts when generating their noises. A few milliseconds after making a cry, the middle ear relaxes so the bat can receive the echo.

Final Thoughts- Auditory System
The Quiets will likely employ an auditory system similar to what is seen in bats. We will expect that they will have a very developed and sensitive inner ear, which is what we see exposed during the film. We expect that the reason that the outer scales are able to rotate and shift is to allow for improve localization of sound, in a similar way to how rabbits or cats and turn their ears to hear certain sounds better. Furthermore, we expect that their ears will be in slightly different positions or offset on the skull to allow for better three-dimensional hearing, similar to what is seen in an owl. The ultrasonic frequencies they use to echolocate will be their primary means to make their way through the world. However, their echolocation will also work against them. The high frequency picked up by the daughters cochlear implant seems to hurt the Quiet, potentially generating some form of resonance frequency that the quiet has no means of combating. Furthermore, their new arrival on Earth will mean that they will still have difficulty interpreting the sound waves that return to them. They will have no frame of reference regarding what is prey or not. This could explain their violent outbursts at all forms of sound and their difficulty detecting humans when they are not moving.


Quiets- Ecology 1
Paramount Pictures, 2018


Because the quiets are an invasive and truly alien species from another planet, we can’t say too much about an evolutionary timeline. What we can do is use our knowledge of evolutionary processes to “build” the quiets.


The quiets don’t have any eyes, hunt by sound, and have long forelimbs tipped with claws. As far as Earth animals go, they look a lot like a weird and gigantic bat. For them to get the way they are now, they would have to have come from a either a dark planet or would have existed within an extensive cave system. Their ability to maintain such a high level of energy on a very dark planet (which would likely be extremely cold) is questionable, so we favour the cave explanation. The resemblance to a bat favours this evolutionary history as well.

The quiets ancestor was probably a small, bat-like organism that flew and used echolocation to hunt for prey. Some mutation developed that made the skin of the ancestor harder, conveying an advantage over the non-armoured ancestors, and if this trait was heritable the offspring of this mutant outcompeted the other ancestors. Over time, this armor became thicker and harder, also making the ancestor heavier and less able to fly. Eventually, the heavier mutants lost the ability to fly completely and had to crawl around the caves that they called home.

After losing the ability to fly, the selection against being heavy was removed, and now the organisms could grow larger and larger. If they went deeper into the cave system and used their echolocation for navigation and hunting, the organisms would have lost their eyes completely, as they are costly organs to maintain and are a waste in caves without light. Their final size probably indicates that the caves systems they inhabit are vast and spacious, with high levels of connectivity.


In the movie we never see the quiets attempt to remain quiet themselves, meaning that they are likely the top predator on their home planet as well. They do seem to have territory, as they don’t interact with one another. Because of this, we are going to say that part of the reason the quiets have this impenetrable armor is to protect themselves from other quiets.

Although the armor may have been advantageous while the ancestors were still small and prey, now that these organisms are so large and predatory the only benefit it is serving is to protect them from other members of their own species. The only thing that can kill a quiet is another quiet, but due to the armor and natural weapons of a quiet this would be an incredibly costly endeavor. So unless the quiet in question is old, injured, sick, or otherwise incapacitated it is not likely to be vulnerable to predation by another quiet.


As large apex predators with sharp, dagger-like teeth the quiets are obligate carnivores and have to eat a lot of meat to survive. No animal on Earth is adapted to avoid predators that hunt exclusively with sound, so all small mammals are vulnerable to them (seen in the film when a racoon is killed). Humans, though large animals in our own right, are very much vulnerable to them, both in the wild and within structures such as houses or farms.

The only organisms that are likely to avoid severe predation are aquatic and marine animals, as well as birds. We see the quiet swimming in the movie, but this is shallow water and the massive quiet can easily stand in it. Because the quiets use sound to see and hunt, they can’t “see” fish or other aquatic animals below the water’s surface. One thing they could do is hunt for fish by echolocating the ripples on the surface, like the fisherman bat (Noctillo leporinus), but this behavior isn’t likely to evolve as there are plenty of prey items available on land.

Non ground-dwelling birds will also likely be safe, though some species will also be preyed upon.


The quiets’ invasion and subsequent domination of Earth is a perfect example of an invasive species with no natural competitors wiping out the native species. This is a massive problem we deal with today, due to non-native species being introduced to new environments (accidentally or otherwise).

Because they are in an environment that isn’t prepared to handle them, they easily wipe out the native species that may have been competitors, in addition to decimating prey species populations. This can be seen in Australia where introduced cats wiped out marsupial populations, or when humans killed off the dodos that didn’t have any natural predators.

The general trend of successful invasive species is that they establish themselves, and their population increases and range spreads until they hit a certain point, at which point they stabilise before eventually decreasing somewhat. At the point of the movie they do not seem to have hit a ‘carrying capacity’, and their ranges are probably expanding to areas that would normally be beyond their natural habitat. Once populations grow too large, competition within the species itself will likely drive the population down to a more stable level, and prey species will become more scarce.


As a large mammal-equivalent, these organisms are going to reproduce sexually. Larger organisms on Earth don’t breed as often as smaller ones, with gestation times ranging from less than a year to a year and a half or so.

For these territorial organisms to interact and reproduce, they are likely to follow some of the same patterns as large territorial animals on Earth. The males probably hold and defend territory from other males, with females either holding territory of their own and/or seeking out male territory when they are ready to mate. After mating, the females either raise and care for their young for a short period of time, or the young come out ready to fend for themselves. This is more likely, as these organisms are coming from an environment with such intense competition that they need to be ready at all times.


Po-Yu Chen, Albert Yu-Min Lin, Joanna McKittrick, Marc Andre Meyers. Structure and mechanical properties of crab exoskeletons. Acta Biomaterialia. Volume 4, Issue 3, May 2008, Pages 587-596


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