We all know the feeling – you’re so hungry you could eat a horse. But have you ever been so hungry you’ve actually considered eating yourself? Believe it or not, there are some animals out there that will resort to self-cannibalism when food is scarce.
If you’re searching for a quick answer, here it is: The only animal known to eat itself due to extreme hunger is the Arabian camel.
In this article, we’ll take a deep dive into the curious and unsettling phenomenon of animals that feast on their own flesh and blood to survive. Which species is driven to this gruesome act of self-preservation? How do they go about consuming their own bodies?
What biological mechanisms allow them to live through the process? Read on as we explore the macabre science behind animals that eat themselves when hungry.
The Extreme Diet of the Arabian Camel
The Humps Provide Sustenance
The Arabian camel is truly a marvel of biological engineering. These hardy desert dwellers can go for extended periods of time with little or no food and water – an ability enabled by the curious humps on their backs.
As it turns out, these humps function as natural food storage units, packed with dense nutritious fat that can be metabolized when food sources are scarce (1).
During times of plenty, the Arabian camel packs away surplus calories into their hump “pantry”, enabling the tissue to swell up to 80 pounds. But when pickings are slim, the humps provide a vital supply line of concentrated energy to keep the camel going.
As the fat store gets burned through, the hump shrinks and flops to the side. An 800-pound camel whose hump is depleted can lose up to a quarter of its body weight, becoming extremely gaunt until conditions improve (2). Talk about peak physical fitness!
Eating Muscle and Fat Reserves
If drought and famine drag on, camels can take their self-cannibalization to the next level. Scientists found that under desperate conditions with no food available, camels will start breaking down non-essential muscle and fat reserves to survive (3).
As a last resort, an emaciated camel will even start catabolizing proteins from vital organs like the heart and liver. Why go to such extremes? Well as the old adage goes – “it’s not crazy if it works!” For the tenacious Arabian camel, extreme fasting enables survival in unforgiving desert climes.
Researchers noted that this ability to essentially self-digest is unique to camels in the animal kingdom (4). No other mammal can maintain normal body temperature and physical activity for so long without food.
Truly, millennia of evolution have turned the Arabian camel into the undisputed heavy-weight champion of harsh desert environments!
While extreme, the Arabian camel’s ability to tap into hump fat stores and bodily tissues helps ensure survival in the unforgiving desert landscape where food sources can be extremely scarce. Clearly, this creature offers a fascinating glimpse of just how far biological adaptation can be pushed!
Other Animals Known to Self-Cannibalize
Mantis Shrimp
Mantis shrimp, also known as stomatopods, are marine crustaceans that occasionally display cannibalistic behavior, especially when they are hungry and can’t find other prey. They have powerful raptorial claws that they use to strike and smash prey with incredible speed and force.
When food is scarce, they may attack each other, with larger adults preying on smaller juveniles of their own kind.
According to a 2021 study, cannibalism rates in mantis shrimp can reach up to 30% in deprived conditions in captivity. In the wild, encounters between mantis shrimp may also sometimes lead to fatal attacks, including cannibalism.
Factors like population density in their habitats can impact how often this occurs when they compete for limited resources.
Chinese Softshell Turtles
The Chinese softshell turtle is an aggressive omnivore that will eat anything it can capture and swallow whole with its sharp beak. According to wildlife experts, when these aquatic turtles are sharing tight living quarters, especially in artificial ponds or tanks, cases of cannibalism may occur between juveniles or between an adult and juvenile turtle.
For example, researchers from Zhejiang University recorded observations of an adult male Chinese softshell turtle attacking and eating two juvenile turtles in a small pond over the course of a few days.
The experts speculated that due to the high stocking density and lack of food resources, the adult turtle resorted to cannibalism for sustenance.
Hamsters
Pet hamsters like Syrian or Roborovski hamsters are typically perceived as cute, harmless pets. However, various incidents and reports indicate that when kept in inadequate conditions, hamsters may attack and consume infant hamsters in their litter, essentially resorting to cannibalism and infanticide.
Reasons range from the stress of captivity, confusion over scent signals, or simply to eliminate resource competition in cramped quarters. According to veterinary experts, providing nursing female hamsters extra protein sources and more spacious housing can curb such harmful tendencies.
The Biological Process of Autophagy
Breaking Down Cells for Fuel
Autophagy is an amazing biological process that allows cells to essentially eat themselves for energy. When a cell is starved or stressed, it can activate the autophagy pathway to break down unnecessary or damaged components into reusable parts.
This provides fuel to keep the cell running during tough times. It’s like cellular recycling!
Here’s how it works: first, a double membrane structure called the autophagosome forms around the cellular junk that needs to be removed. This could include old or defective proteins, viruses, or even whole organelles like mitochondria!
The autophagosome then fuses with a lysosome, which contains enzymes that can break down all the cellular contents into their building blocks. Those amino acids, fatty acids, and other goodies are released back into the cell to be used for energy production and new protein synthesis.
Some cool facts about autophagy:
- It was first discovered in the 1960s when scientists saw unusual vesicles of”self-eating” in cells.
- Yoshinori Ohsumi won the 2016 Nobel Prize in Medicine for his groundbreaking work elucidating the autophagy machinery.
- Many neurodegenerative diseases like Alzheimer’s and Parkinson’s are associated with disrupted autophagy.
An Evolutionary Adaptation
Autophagy likely evolved in primitive single-celled organisms as a way to survive starvation and other environmental stresses. The ability to quickly mobilize reserves of energy and raw materials from their own cytoplasm would have provided a critical survival advantage.
Scientists believe autophagy originated at least 2 billion years ago.
As multicellular organisms evolved, autophagy took on additional housekeeping roles within the body. It allows cells to destroy and recycle damaged structures and proteins that could be harmful. It also plays a key role in cellular differentiation, immunity, and preventing cancer.
Mice studies have found that deleting essential autophagy genes is lethal at birth.
Some interesting evolutionary facts about autophagy:
- Ancient genes involved in autophagy are highly conserved across eukaryotes from yeast to humans.
- Plants also utilize autophagy, allowing them to recycle nutrients from leaves before winter.
- Autophagy may have facilitated the evolution of multicellular organisms by preventing accumulation of toxins.
Is Self-Cannibalism Safe for Animals?
Risks of Nutrient Imbalances
Self-cannibalism or autosarcophagy carries significant health risks for animals who engage in it. Consuming one’s own tissues can lead to dangerous nutritional imbalances if not done carefully. For example, an animal eating its own muscles would get plenty of protein but not enough fat or carbohydrates.
This could potentially lead to protein toxicity, nutrient deficiencies, and even death if the practice continues unchecked. Some level of self-cannibalism may be sustainable if balanced by consuming other food sources.
However, relying solely on self-cannibalism is extremely risky except in desperate situations with no other food available.
Excessive self-cannibalism can also deprive an animal of essential vitamins, minerals, and micronutrients normally obtained through a varied diet. Consuming their own nutrient-rich organs like liver may help offset this, but likely not completely.
For instance, vitamin C is not stored in tissues and must be continually replenished through food. Self-cannibalism to the exclusion of other nutritious foods could quickly lead to deficiency. Without a balanced intake of all necessary nutrients, animals engaging in autosarcophagy long-term are prone to illness, immunodeficiency, and developmental issues.
Infections and Diseases
Eating one’s own flesh also carries considerable risk of transmitting infectious diseases. Wounds inflicted during self-cannibalism create an entry point for dangerous pathogens to invade the bloodstream. Consuming infected tissue would then pass parasites, bacteria, or viruses back into the body.
This can initiate a harmful cycle of reinfection. Prion diseases like mad cow are particularly concerning, as prions can linger in nerve and brain tissue even after cooking.
Beyond transmission of preexisting infections, self-inflicted wounds also raise the chance of sepsis from invasive opportunistic microbes. Anaerobic bacteria thriving in the oxygen-deprived intestines may migrate through the GI tract to proliferate in necrotic flesh or open wounds.
Necrotizing fasciitis and gas gangrene are grave threats if such invasive infections are not quickly controlled. Proper wound care and disinfection are essential for animals practicing self-cannibalism to avoid these severe complications.
In short, autosarcophagy can endanger animals through nutritional imbalance, deficiencies, and disease transmission if not approached cautiously. While it may serve as an emergency survival mechanism, chronic self-cannibalism is physiologically taxing.
A diverse, well-balanced diet is far safer and healthier long-term. Care should be taken to minimize risks if self-cannibalism cannot be avoided.
Other Extreme Survival Strategies
Hibernation and Torpor
Some animals have evolved amazing abilities to survive long periods without food by lowering their metabolic rate and body temperature through hibernation or torpor. Bears are well known for hibernating through the winter months in dens.
Their body temperature drops only slightly, but their metabolism can slow down by up to 75%, allowing them to conserve energy. Rodents like ground squirrels also hibernate, with their body temperature plummeting nearly to freezing.
This dramatic drop in body temperature allows them to survive for months without eating.
Other animals like bats and hummingbirds use daily torpor to conserve energy. Their body temperature and metabolism drops for a few hours each day, allowing them to endure periods when food is scarce. For example, the common poorwill, a small bird, can lower its body temperature to nearly ambient temperature at night and reduce its metabolism by 99%.
This allows it to survive without eating for extended periods during migration. By using torpor and hibernation, animals can dramatically reduce their energy requirements to survive extreme conditions.
Liquid Diets
Some animals can prolong survival without food by switching to liquid-only diets. For example, camels can lose more than 30% of their body weight as fat and water stores before death. They are specially adapted to endure weight loss and dehydration in the desert.
Camels can go for over a week without water in the heat and survive on the fluids stored in their hump. Vampire bats can survive long fasts by switching to a liquid diet of blood alone. Their digestive system is adapted for this liquid food source.
By restricting themselves to liquid-only diets, animals can prolong survival without solid food.
Lowering Metabolic Rates
Some animals have very low metabolic rates, allowing them to endure amazingly long fasts. The metabolic rates of pythons drop by up to 72% after eating a large meal. This slows their digestion and allows them to survive for months without eating again.
Land snails are champions at lowering their metabolism and can survive over 5 years without food. By entering estivation, their metabolic rate drops to just 1-5% of normal. With extremely slowed metabolisms, some animals can endure months or even years of fasting.
Conclusion
While self-cannibalism is an exceedingly rare survival strategy, its existence reveals the incredible capacity of some species to adapt when facing starvation. By studying animals that resort to eating themselves for sustenance, we gain insight into the evolutionary forces that drive such radical self-preservation behaviors.
However, we must be mindful that autocannibalism can carry health risks and should not be glorified. Ultimately, the best way to prevent animals from needing to eat themselves is to provide adequate food, water, and care.
The next time you complain of being hungry enough to eat your arm, remember the peculiar animals that actually do! Self-cannibalism remains one of the strangest adaptations in the animal kingdom, but it speaks volumes about the powerful will to endure against all odds.