The number of taxonomically defined animal species is around 1.5 million. These are classified into 32 phyla according to their distinct features. One of these is the phylum of Tardigrada.

These cute, tiny water creatures were discovered in 1773 by Johann August Ephraim Goeze. Despite being aquatic, these animals were called “water bears” because of their legs; and because of their resemblance to pandas, they were named “Tardigrada,” meaning “slow stepper,” by the Italian biologist Lazzaro Spallanzani. Tardigrades also look like dwarf rhinos and armadillos. There are about 1,000 different species in the Tardigrade phylum.

Tardigrades live in habitats with variable amounts of humidity, from high mountains to deep oceans, and from polar regions to the equator. They are especially found in lakes, freshwater springs, or on stone walls, mosses, lichens, leaves, and litter.

As cute, charismatic, miniature animals, tardigrades can be seen under a microscope. The length of adults can reach 1.5 mm, while the smallest ones are under 0.1 mm; their larval length is only around 0.05 milimeters. Their body is covered with a strong but elastic material.

Animals grow in two ways: via an increase of cell numbers or the enlargement of a single cell. In Tardigrades, generally the latter is observed. These animals possess a hard external skeleton, like insects, and this structure changes as they grow.

Their bodies are composed of five sections: a distinct head in addition to four body parts, each equipped with claws. They walk using the short, blunt feet under their bodies. Their clawed legs help them cling to sand particles or plant surfaces. Their hind legs are used for snatching and slow acrobatic movements. They have a sharp mouth, called a “stylet,” which enables them to consume plant cells, algae, small invertebrates, and even their own kind.

They are provided with anatomical and physiological features similar to larger animals, including a digestive track and system: a mouth, esophagus, stomach, small intestine, anus, well developed muscles, a pair of abdominal nervous systems, and a brain. The body lumen of Tardigrades are filled with a fluid that is in contact with every cell and this provides them with their necessary nutrition and gas exchanges without the need for a circulatory or respiratory system. Their respiration occurs throughout their body surfaces. Because of their physiology and ability to quickly reproduce, Tardigrades can be used as a model organism for education and research. The cell count of certain species of Tardigrades at birth never changes during their lives. While some species contain around 40,000 cells, some have fewer. Their reproduction can be sexual, but it also can occur via parthenogenesis (offspring development without the fertilization of the egg).

Tardigrades: Organisms of extreme conditions

Tardigrades are created with a resistance to a wide range of temperatures, pressures, and radiation. Therefore, they can live in environments where many living things die. They can survive a temperature of 150 C for minutes, and can also live at minus 200 C without suffering any damage for days; they can even stay alive at temperatures near absolute zero (−273 C).

Some Tardigrades can live at extreme low pressures, including situations approaching a vacuum, or at extreme high pressures, such as 600 times the normal atmospheric pressure. This pressure is six times the pressure present at the depths of the Mariana trench, the deepest part of the Earth’s oceans (roughly 11,000 meters). This was discovered when Tardigrades were taken to space and exposed to different pressures. When brought back to Earth, they were still alive.

They can also survive in environments with no humidity for 10 years, and they can stay alive in places where radiation is 1,000 times more (5000 Gy to 6200 Gy) than many organisms can endure (10 Gy is fatal for humans).

Hibernation – a dead phase

How does a Tardigrade stay alive in detrimental conditions?

When they are exposed to conditions unsuitable for life, they enter a semi-dead phase called Cryptobiosis. One of the most distinct changes during this state is that their metabolic speed slows down to near zero, and they experience programmed dehydration. In very low temperatures, Tardigrades’ water ratios drop from 85% to 3%. This way, damages that can occur by freezing are prevented. As is well-known, the main hazard during freezing is the cell membrane damage caused by the crystallization of cellular water.

During the dehydration stage, trehalose sugars are synthesized (this also happens when Tardigrades are faced with low temperatures). This sugar prevents possible damages to the cell membranes during freezing and water loss. This sugar is very intriguing for the pharmaceutical industry because of its potential use in the prevention of freezing-related damages in organ transplants.

Another benefit of dehydration is resistance to radiation. This is because reactive molecules generated in the cell by the effects of radiation cannot cause a reaction in a dehydrated medium; due to the low water concentration, the possibility of harmful reactions drops.

Cryptobiosis does not only take place during dehydration. It also happens during periods of low temperature (cryobiosis), high salinity (osmobiosis), and low oxygen. By being able to hibernate, Tardigrades are important for space research. Maybe during interplanetary trips, passengers could be hibernated by freezing.

Tardigrades could have other uses for medical purposes. Certain disease-causing microorganisms could be dehydrated without killing them via Cryptobiosis. This way, “weakened organisms” contained in vaccines get to be stored in a dry fashion, eliminating the need for freezers, making them easier to store and distribute. Similar technologies could also be employed for the conservation of seeds, sperms, blood, and various nutrients.

Water has a vital role in maintaining the life of the cell. For example, 70% of the human body consists of water; also, approximately 70% of the earth is formed of water. Chemical reactions happening inside cells take place in liquid environments; in other words, life activities have been made to depend on water.

While water has such a vital importance for creatures, is there any living being that can live without water? The answer to this question is yes. For example, the African Lungfish (Protopterus), which is created with this special quality, can live without water for four years in hard times.

It is well-known that bears go into hibernation as a result of a God-given instinct during the winter cold. Storing necessary energy as fat in their bodies in order not to freeze, decreasing their body metabolism to the minimum rate, and being guided to choose a place to be protected from the cold during winter hibernation are important features bestowed on these living beings.

Another special features bestowed on some animals is the capacity for summer hibernation. This sleep is a marvelous quality that enables some animals to be able to live in hot and dry climates. Summer hibernation is the process of spending very hot summer days between sleep and lethargy in order to handle hard circumstances. A kind of silence is felt in the whole of nature during the extremely hot months of summer. This silence is caused by animals being in their summer sleep. Lungfish is one of those animals. There are various types of lungfish around the world: Queensland Lungfish (Neoceratodus forsteri), which is as long as 6 feet and which lives in the Burnett and Mary rivers in Australia; African Lungfish living Central Africa; 6 feet long Protopterus aethiopicus; 4 feet long P.dolloi; P. amphibious, which is written to be longer than 13 feet in some records; and Lepidosiren paradoxa living in South America.

Quite a lot is known about the summer sleep of the lungfish in Africa (Dipnoi). When the river water which flows from the treasures of God’s mercy is withdrawn during the summer months, the lungfish, which sink into wet clay by God-given instict, wait for a drawn back of water in a state of lethargy with having very low metabolisms. The fishes open a hole for themselves on the mud (down rivers and lakes) when rivers and lakes start to dry. When the mud goes into a drying process, specially featured mucous membrane that are put onto fishes’ skins start to work fast and fishes’ bodies are covered by a secreted mucus-like adhesive substance like a water-resistant cocoon. Fishes can stay alive by sleeping about 7-8 months during deadly summer hots with the amount of accumulated water inside cocoons. Although many fishes obtain the necessary oxygen through their gills, lungfish are created with an interesting special feature. The thin membrane bladders (gas bladders) that are responsible for regulating water level in other fishes are organized into a kind of breathing organ in the lungfishes by equipping with large amount of blood vessels in order to perform like lungs. God the Almighty can make different organs (analog organ) perform similar tasks as He does make similar organs (homolog organ) perform different tasks. None of these organs, which are created as the manifestation of God’s eternal knowledge and omnipotence, are characterized as being developed by their own through coincidental mutations. In contrast, every organ is created in the most appropriate character and capability to ensure maintenance of animals’ lives in the best way. Otherwise, we had to imagine those fishes that could know dry season with every aspects and that have the capacity and knowledge to change their organs as they want.

How do the fishes living in a water-resistant and durable cocoon obtain the necessary oxygen for themselves? The hole kept inside mud is used to get oxygen when oxygen inside cocoon reduced. The cocoon’s membrane made from mucus protects the little amount of water around the fish in mud but does not block the oxygen transition. While the dried mud works like a turbot against sun lights, the hole on the wall is kept. The lungfishes shrink around 1 inch during the summer sleep, since they use (burn) some of their fat and muscle tissue. When rains start and water fills lakes and rivers, the mud turbot that keeps lungfish dissolves; and the lungfish starts to continue its normal life in water.

You would have thought them awake though they were asleep. We caused them to turn over to the right and the left, and their dog lay outstretching its two forelegs on the threshold. Had you come upon them unprepared, you would certainly have turned away from them in flight, and would certainly have been filled with awe of them. (Kahf 18:18)

Religion involves abstract concepts, including the belief in a Supreme Being that can intervene in human affairs. Such intervention can take the form of divine communication, which in its written form becomes scripture, the holy word that exceeds in quality and wisdom the literary achievements of mortal writers. These writings outline basic beliefs, and provide counsel that give humans certain guidance as they pursue their mortal pilgrimage in an uncertain world. Besides their profound impact on individuals, these guidelines help to form, and even transform, cultural and behavioral patterns that unify group thinking and social structure, that influence legal codes, that shape educational programs, and that influence life in innumerable ways. Religion, with its reliance on faith in the unseen, seems to clash with the scientific method, with its insistence on empirical data, on proof. Yet no such clash exists in true religion, which embraces all truth, visible or invisible, from whatever source. Faith and science, then, are merely different ways of knowing, two useful means of discerning truth.

Science and religion are so intertwined that some church names announce the connection: Church of Scientology, and Church of Christ, Scientist. Some of the great scientists do not feel there is a science-only limit on their research, and perceive themselves as much more than narrowly-focused scholars. For example, Dr. Francis H. C. Crick (1916–2004), the co-discoverer of the current DNA double helix model, researched the human spirit;¹ Dr. Henry D. Eyring (1901–1981), world famous for his work on reaction rates in chemistry, saw no conflict between authentic religion and accurate science.² These and innumerable scientists have affirmed belief in the existence of the human spirit and life after death.

The claim that the Holy Qur’an is scripture sent by the Creator Himself should be easily verifiable in any stage of human civilization, according to the degree of knowledge a society has at a specific time. Muslims believe that the Qur’an is the last and final revelation of God, the miracle of miracles. It is the ultimate book of guidance and warning for the whole of humanity, a merciful message for mankind sent by God through the Prophet Muhammad (may peace be upon him). Therefore, Muslims critically investigate the veracity of its claims, and analyze them scientifically; they find every aspect of it to be true according to well established scientific facts. It is pertinent to mention that we are only talking about well-established scientific facts, not theories or hypotheses, which are numerous and prone to change.³ Modern humans, however, too often have sold themselves short by limiting the quest for truth to empirical logic and reason, by granting science supremacy over scripture. This is not to say that the scientific quest is fruitless, simply that it is unduly limited. Islam has made reason the ultimate judge in everything; in the Qur’an, God links disbelief to the refusal to use reason: “Those who disbelieve simply do not use their reason and neither do they understand” (Baqara 2:171). Reason and understanding, then, are meant to buttress belief, to fortify faith. Otherwise, one incurs the merited displeasure of God, who not only compares the disbeliever to one “who hears the sounds of a call but does not distinguish any word or idea,” but also teaches that to converse with such a person “is like talking to the deaf, dumb, and blind” (Baqara 2:171). In the Holy Qur’an, God calls upon humans to look into the universe and discover its construction and structure. He commands them to do so in the conviction that their investigation of the organization of the universe will lead them to the discovery of God and His Unity: “In the creation of the heavens and the earth, in the succession of day and night, in the phenomena of ships sailing across the seas with goods for the welfare of human beings, in the fall of rain water from sky to quicken a dead earth, in populating the earth with all species of animals, in ordering of winds and clouds between sky and earth – in all these there are signs and pieces of evidence for those who reason” (Baqara 2:164).

According to the Qur’an, any scripture claiming to be a divine revelation must also be acceptable on the strength of its own reason and logic. The Qur’an is not a book of science but one of signs (each verse in the Qur’an is called aayaat which also means “sign”). Nevertheless, it conveys scientific knowledge; of the 6,000 or more verses in the Qur’an, over 1,000 of them deal with core scientific facts. For example, Anbiya 21:30 suggests that the discovery of an expanding universe, commonly called the Big Bang theory, was revealed by illuminating inspiration long before it was discovered by such scientific luminaries as Edwin Hubble and Alan Guth: “Do not the Unbelievers see that the heavens and the earth were joined together (as one unit of Creation), before We clove them asunder?” The Holy Qur’an is full of scientific explications, including tantalizing intellectual nuggets that describe the spherical nature of planets, the nature of their orbits, human embryology, and the fundamental role water plays in life on planet Earth.⁴

In this article, we would like to point out a yet another scientific secret that apparently has not been analyzed by Qur’anic scholars. The verse with which this article begins (Kahf 18:18) invites discussion of two important topics that are of interest to modern physicians and others: hibernation, and the prevention of bedsores that may afflict humans during times of extended immobility, as in hibernation or serious paralytic or other illness. In the Qur’anic story of the “people of the cave,” two signs appear: an instance of long-term sleep (hibernation) and a simple method to prevent bedsores.

The chapter state that a small group of youth, believers in One God who were fleeing their own family for fear of persecution, took refuge, and sought divine grace in a large remote cave, for which they are known as the “people of the cave.” They were overtaken by sleep in the cave, which was away from sunlight and is mentioned as one of the Signs of God.

These youth slept in the cave with their dog for an exceptionally long time (309 years according to the verse 18:25), during their slumber their physical position was periodically changed, and the cave was away from direct sunlight.

You would have seen the sun, when it rose, moving away from their Cave to the right, and when it set, turning away from them to the left, while they lay in a spacious hollow in the Cave. That was one of God’s signs. (Kahf 18:17)

Let us now discuss these topics: the hibernation or a state of sleep in which they thought they were awake-a hypnogogic state, the repeated turning over, and the avoidance of sunlight in the cave. First, let us examine hibernation, which is defined as a state in which mammals, and some non-mammals, experience depressed metabolic activity characterized by exceptionally slow breathing and lower body temperature during an extended period of inactivity. A means of rest and energy conservation, hibernation reduces the need for food by relying on fats already present in the body itself. Bears are perhaps best known for their hibernation during winter, when food is more difficult to acquire, but squirrels, bats and rodents also hibernate. The Common Poorwill, a bird found in North America, hibernates, as does the Western Diamondback rattlesnake, and the Dwarf Lemur, which hibernates more than half the year (sometimes in warm temperatures). It should be noted that in the Qur’an the hibernation is described as a hypnogogic state, a state when a person believes that he or she is kind of awake.

Scientists and others are currently intrigued by the potential that hibernation offers to humans. Could induced hibernation save a seriously injured person until appropriate medical help arrives? Could hibernation reduce the demands on the heart and other organs of seriously ill patients? Could life be extended through this means? Would persons suffering from clinical depression benefit from some “time off” with no stress? What about astronauts, who would benefit from hibernation during long flights to distant locations in space?⁵ The Qur’an seems to suggest the possibility of space travel, as allowed by God: “O company of jinn and men, if you have power to penetrate (all) regions of the heavens and the earth; then penetrate (them)! You will never penetrate them save with (Our) sanction. Then, which of the favors of your Lord will you deny?” (Rahman 55:33–34)

Is there any evidence of human hibernation in recent years?

Of course, the story of the believers mentioned in the Qur’an relates to a miracle that occurred long ago and it is mentioned to show the power of belief, and as one of the small signs denoting God’s existence and His mercy. However, documented occurrences of human hibernation in recent years have been highly publicized.

For instance, in 1991, Brittany Eichelberger, a West Virginia three-year-old, was rescued from a late December snowdrift, on a night when temperatures fell to –3 C. She survived, lost only a portion of one toe, and suffered a little from a weak arm and some minor pneumonia. A decade later, thirteen-month-old toddler Erika Nordby seemed to have frozen to death after crawling into the cold one night in Edmonton, Canada in February 2001. Although clinically dead, she came back after serious treatment by doctors who dealt with frostbite issues and were astounded to find that she suffered no major brain or other physical injuries that would be expected for one who had been outside for perhaps three to four hours. Although the brain had been deprived of oxygen for an extended time period, apparently the decreased body temperature and the resultant metabolism slowdown reduced the need for normal brain activity and blood flow. These “miracles” have prompted increased interest in whether similar miracles could be intentionally performed to prolong life. Karlee Kosolofski, a two-year-old, survived a six-hour ordeal in Rouleau, Saskatchewan, Canada on a night so cold (–22 C) that her body temperature plummeted to a documented 14.16 C (which placed her in the Guinness Book of World Records). A physician who helped her survive likened her badly-frozen legs to ice blocks. She lost a leg, had another severely scarred, and required grafts and surgeries. Ironically, Krista Rempel, the paramedic who was first on the scene in Rouleau later arrived first in Edmonton, to rescue Erika Nordby.⁶

To religious observers aware of the dual-rescue “coincidence,” it seemed apparent that the same paramedic was assigned to serve by God again to witness another miracle.

Cryogenics, which deals with the changes in materials when frozen, has helped humans (including astronauts and heart patients) by improving materials that help propel spacecrafts or that make open heart surgery safer. But what about the branch of cryogenics called cryonics, which deals directly with people, specifically frozen people? Could people be intentionally frozen until specialized help arrives within a few hours? What about within a few decades? Could patients be placed in suspended animation until a surgical procedure is improved or until genetic engineering becomes more advanced? So far, cryonicists have not succeeded in freezing and then reviving humans.

Hibernation induction (inducement) triggers (HIT)

Scientists have good reason to hope that induced hibernation can work on humans because it has worked on animals. For example, when HIT-hibernation induction (inducement) trigger-is extracted from the blood of a hibernating squirrel in winter and injected into an active squirrel in the spring, this second squirrel goes into hibernation. HIT can even be shown to induced short-term hibernation in a monkey, which normally does not hibernate.⁷ HIT, which a bear’s body releases when the temperature decreases, is thought be a type of opiate that is similar to morphine in its chemical makeup (http://www.sciencemadesimple.com/animals.html). Could HIT help terminally ill patients, such as cancer patients who take morphine? Could it lengthen the time that animal or human organs can remain independent in transplant operations? Studies have shown that a synthetic substitute called DADLE, can dramatically “increase the time animal organs can survive in the laboratory from 8 hours to 46 hours by using an opiate-like compound in combination with a preservation method that keeps a number of organs from the same donor animal linked with connecting veins.”⁸

In the Qur’an we do not find mention of the hibernation inducing agents that may be present in the cave, but it is intriguing to consider that various kinds of gases, including carbon monoxide and hydrogen sulfide, are found in dark caves. Called oxygen-mimetic gases, these have a molecular similarity to oxygen. Because they mimic oxygen in their binding capacity, these gases can inhibit the body’s capacity to utilize oxygen (known as oxidative phosphorylation). This inhibition is important because it can reduce metabolic activity to the point that a state like sleep or even hibernation can ensue. Later, revival occurs as organisms are again placed in regular air. The cave story in the Qur’an suggests that the cave was intentionally deprived of sunlight and kept cool.

With regard to the second sign, the Holy Qur’an mentions a state of “a very long sleep” in a group of believers and their dog. One of the most interesting aspects of this miraculous sleep is that God says, “We caused them to turn over to the right and the left.” As any health care professional is well aware, a human being cannot lie down on a bed or on the ground for a long time without developing bedsores unless they change positions periodically. It is continual, unrelenting pressure that damages skin and other tissue and causes bedsores (pressure sores), especially when this pressure is applied to areas of skin that cover areas in which bones or cartilage are prominent. The parallel between the modern remedy for bedsores and the universal wisdom of the Qur’an is impressive.

There are numerous secrets in the Qur’an that we see the world has ignored due to apathy, ignorance, or arrogance. Muslims, as well as others who seek for truth wherever it exists, would do well to pay closer attention to the Qur’an and to the aayaat or signs of God. As this article demonstrates, faith complements science at its best, and true science becomes a subset of true religion. Together, the two function more like an intertwined double-helix in DNA than like two geometric rays pointed in different directions.

Notes

1. See Astonishing Hypothesis: The Scientific Search for the Soul, 1994.

2. See The Faith of a Scientist, 1969.

3. See Thomas S. Kuhn, The Structure of Scientific Revolutions,1962.

4. These and many other subjects have been explored by many authors-notably Dr. Maurice Bucaille, The Bible, the Qu’ran and Science: The Holy Scriptures Examined in the Light of Modern Knowledge (1990), but also by such scholars as A. Abd-Allah, The Qur’an, Knowledge, and Science (USC-MSA Compendium of Muslim Texts. University of Soutern California. Internet. <http://www.usc.edu/dept/MSA/quran/scislam.html>. Accessed 30 May 2008.), and Dr. Zakir Adbul Karim Naik, Qur’an and Modern Science – Compatible or Incompatible? (2003; see also http://www.irf.net/irf/drzakirnaik/dznindex.htm (download of text), http://www.irf.net/irf/ drzakirnaik/index.htm, and http://www.islamicvoice.com/may.2000/religion.htm).

5. Tariq Malik, “A Sleepy Science: Will Humans Hibernate Their Way Through Space?”, Science 12 October 2004. Internet. http://www.space.com/scienceastronomy/ scitues_hibernation_041012.html.

6. CBC News Online, “Hypothermia.” Indepth: Health. 16 July 2004. Internet. http://www.cbc.ca/news/background/health/hypothermia.html. See also, Robert Roy Britt, “New Hibernation Technique Might Work on Humans.” 21 April 2005. Internet. http://www.livescience.com/health/050421_hibernation.html, John Harlow, “Race to be first to ‘hibernate’ human beings.” The Sunday Times. TimesOnline. 27 May 2007. http://www.timesonline.co.uk/tol/news/uk/science/article1845294.ece

7. Great Moments in Science, ABC, http://www.abc.net.au/science/k2/moments/s1038546.htm.

8. (Neil Swan, “Hibernation-Triggering Opioid Extends Life of Organs for Transplantation.” NIDA Notes, Research Advances. Vol. 11, no. 1 Jan–Feb. 1996, See also Chien, S.; Oeltgen, P.R.; Diana, J.N.; Salley, R.K.; and Su, T.-P. Extension of tissue survival time in multiorgan block preparation with a delta opioid DADLE. Journal of Thoracic and Cardiovascular Surgery 107:965–67, 1994; Oeltgen, P.R.; Horton, N.D.; Bolling, S.F.; and Su, T.-P. Extended lung preservation with the use of hibernation trigger factors. Annals of Thoracic Surgery; Oeltgen, P.R.; Nuchols, P.A.; Nilekani, S.P.; Spurrier, W.A.; and Su, T.-P. Further studies on opioids and hibernation: Delta opioid receptor ligand selectively induced hibernation in summer-active ground squirrels. Life Sciences 43:1565–1574, 1988; Charles F. Schwartz, MD, Anthony J. Georges, MD, Marsha A. Gallagher, Le Yu, Kenneth S. Kilgore, PhD, Steven F. Bolling, MD, “Delta opioid receptors and low temperature myocardial protection.” Annals of Thoracic Surgery. 1999;68:2089–2092. Internet. http://ats.ctsnetjournals.org/cgi/content/abstract/68/6/2089.

For example, a hibernating woodchuck’s heart rate slows from 80 beats per minute to 4, and its temperature drops from 98 F (36.6 C) to as low as 38 F (3.3 C). If its body heat falls too low, it will awaken slightly and shiver to warm up a bit. If an animal lives in an area where the winter is mild, it may hibernate only briefly, or not at all.

Why hibernation-why do some animals sleep through the winter?

When the cold temperatures and ice of winter arrive, food becomes scarce for animals in the wild. Hibernation is a survival strategy, given by the Lord of all creatures; it is a technique that can be very successful in environments where food is scarce or just difficult to find during a long, cold winter season. Hibernation not only eliminates the need for food-gathering in the winter, but also lets an animal conserve its body energy by slowing down its heart rate and breathing. During the winter we are unable to see some animals, such as bears, in their usual habitat; they have retired to their dens. Since these kinds of animals have little chance to find food in their regions during that period, dropping into deep hibernation or into a torpid state allows them to use their bodies’ energy reserves at a slower rate than they would if they were maintaining themselves at their typical basal metabolic rate. Some ecologists refer to hibernation as “time migration.” Hibernation allows the animal to skip over the cold, stressful seasons and only expend itself fully in those months of abundant food and moderate climatic conditions.

How do animals know it is time to hibernate?

Although there are some apparent signs that indicate the period of hibernation is approaching, this is still a subject of research. In the weeks before hibernation or dormancy, animals prepare their winter beds.

Hibernating animals have something in their blood called HIT, or Hibernation Inducement Trigger; this works something like a clock. Recent research suggests that it is some kind of opiate, chemically related to morphine. As the days get shorter, the temperature changes, and food becomes scarce, HIT triggers hibernation. How and why it happens is still a mystery waiting to be explored.

Are all “hibernators” the same?

Not exactly. Some animals are classified as “deep hibernators,” such as chipmunks, woodchucks, box turtles, black snakes, garter snakes, and toads. Deep hibernation is a state in which an animal is inactive for many days or weeks. In deep hibernation the animal’s body temperature drops to around 41 F (5 C). Deep hibernation is also called “true hibernation.”

Other animals exhibit a less profound inactive state, called “torpor hibernation”; animals such as deer mice, black bears, skunks, and raccoons are examples of such animals. Torpor may be very short-term (during the cold hours of the night, for example) and involves a drop in the animal’s body temperature of no less than 59 F (15 C). An animal in torpor is also capable of relatively quick arousal. While some animals are given the ability of hibernation to survive, some are given other tools by our God. For example, birds do not hibernate, but most species migrate to warmer regions. Fish do not hibernate, but withdraw to deeper waters and their body processes slow down to the point where their food and oxygen requirements are a tiny fraction of the needs during the summer months. Aquatic insects do not hibernate. Most land insects die, leaving behind them their descendants in the egg, larva or pupa stages. Some insects, though, for instance

certain species of mosquito, hibernate in basements, cisterns and such protected places

Do hibernators have to hibernate?

Some hibernators display what is called “predictive dormancy.” These animals go into a hibernative state usually in response to the decreasing length of day, in anticipation of the approaching winter. “Diapause” in insects is an example of this “hardwired” hibernation response. Some poikilothermic (“cold blooded”) animals (like some reptiles and amphibians) also display obligatory hibernative responses as the day length decreases. The reliance of these animals upon warmth from their environment to maintain their body heat necessitates that they anticipate the onset of cold conditions and not be caught out of their hibernaculae by potentially lethal cold temperatures.

Other animals enter their hibernative state only after being exposed to adversely cold conditions. These animals display “consequential dormancy.” The disadvantage of consequential dormancy is that the organism is exposed to potentially damaging environmental conditions (poikilotherms in particular are especially vulnerable to the stresses of consequential dormancy). If, however, the hibernative response occurs immediately after the cold stress, then damaging exposure is minimized. A major advantage of consequential dormancy is that the animal is capable of activity right up until the time that winter conditions become excessively stressful; this means that the animal can possibly even be active all winter long if the season is particularly mild. This flexibility is especially advantageous for species living in fluctuating, unpredictable environments or in species that are expanding their ranges into either higher or lower latitudes.

Is hibernation seen only in cold regions?

Unexpectedly, not. While observing nature and learning about the world, one is astounded by the wonderful work of God Almighty. Although it is often viewed as a phenomenon of colder climates, hibernation also occurs in the desert. A classic hibernator is the desert tortoise, which heads underground into burrows with the onset of cold. In a suspended state, it drastically reduces its metabolic rate, digestion, urination, and defecation. Although some move only slightly during winter, others may take advantage of warm days and head out to bask.

Gall moth caterpillars, insects which most of us have never even heard of, typify the second group. They avoid freezing at all costs. Despite what most of us think, water can remain liquid down to -40 F (-40 C), provided that it is free of impurities, so these caterpillars purify what little water is contained in their bodies by emptying their guts of foreign food particles and bacteria.

In addition, they produce an antifreeze, much like that used in cars, but different than that used by freeze-tolerant animals, to lower the temperature at which ice forms. The combination of these two methods allows gall moth caterpillars to survive winter temperatures as low as -36 F (-38 C).

Survival during hibernation

The hibernating animal is quite defenseless when it is in a deep hibernative or even torpid state. They need to prepare a very secure hibernating den (the “hibernaculum”) to protect themselves as they are now an inactive animal. It is interesting that it is possible for an animal to live after six or seven months without eating, drinking, or passing wastes. For example, less than 1 percent of black bears die in their dens. The main threats to their lives are flooding and predators (wolves, dogs, active bears, and humans). Bears do not usually die of starvation in dens. Most deaths from starvation are before or after hibernation and involve primarily cubs and yearlings. Over-wintering black bears do other extraordinary things.For example, snoozing bears are able to gain all the sustenance they need entirely from within their own bodies. Fat tissues break down and supply water and up to 4,000 calories a day; muscle and organ tissues break down and supply protein. Bears’ bodies are somehow able to take urea-a chief component of urine that is produced during tissue breakdown and that, if left to build up, becomes toxic-and use the nitrogen in it to build new protein.

Hibernating bears also have what would seem to be dangerously high cholesterol levels.Because they live off their own fat, their cholesterol levels are more than twice what they are in summer (and more than two times higher than those of most people). But bears evince no signs of hardening of the arteries or the formation of cholesterol gallstones. Research has shown that hibernating bears generate a form of bile acid that, when administered to people, dissolves gallstones, eliminating the need for surgery. Despite being cooped up in a space about the size of a doghouse, hibernating black bears also appear to avoid muscle cramping and degenerative bone loss. How they accomplish this remains a mystery. Even though a hibernating bear drinks no water, it does not become dehydrated. If we can learn how this metabolic feat works we can use the information to help treat people suffering from chronic kidney failure. During this time, the amount of urine entering the kidneys drops by 95%. Disease is uncommon in hibernating animals. Most parasites of bears are adapted to their host’s hibernation cycle and reduce their demands in winter. Medical researchers are studying black bear hibernation to learn how bears cope with conditions that are problematical for people. The findings are aiding studies of human kidney disease, gallstones, obesity, anorexia nervosa, and other problems. Researchers hope that knowledge of bear hibernation may someday even aid space travel. Another mystery goes by the name of delayed implantation.A female will carry a fertilized egg in her womb for many months.The egg is ready to attach itself to the uterine wall and begin developing into a fetus.But it does not do so until the female’s body gives a signal; it is still unknown precisely what this signal is.This adaptation allows bears to time the birth of their cubs, so they’re not born too early or too late. It also gives the mother a way out if food is scarce. If she has not accumulated enough fat by the time she settles into her den to hibernate, the egg will spontaneously abort. Some biologists see this neat trick as a natural mechanism to control the population. Evidence is mounting that hormone-like substances in hibernating bears may control all these physiological tricks.When injected into other species, both those that hibernate and those that do not, these substances engender hibernation-like effects. In conclusion, we can say that what we know about hibernation may not contain even one half of what is to be known. Hibernation is a sign of the Lord’s existence in the world and His ceaseless protection of creatures.We know that hibernators do not decide to hibernate at will; they are put in that position by their All-Merciful Protector. And all of them are doing their job as actors in a great scenario in the World Theater of God.

Hibernators are intensely active in summer. A part of that activity is building temporary burrows for summer use only. Ground squirrels, (Spermophilus citellus) for example, can build hundreds of such temporary shelters over a single summer, on average 15 shelters in a 10m2 area of open field. These shelters have only the one nest compartment, usally between 30 and 50cm below ground level. By contrast, their shelters for hibernation, sometimes as much as 3m below ground level, are intended for long, repeated use and contain a number of compartments-one for storing large quantites of food (usally dry seeds), one for use as a ‘toilet’, and a third for sleeping.

Before hibernation, animals prepare themselves for the hardship of the very long period of cold by storing up large amounts of fat in adipose tissue under the skin, up to some 40 % of total body weight. These fats are composed of fatty acids which typically have ten or fewer than ten carbon atoms and are consturcted with some double bonds between the carbon atoms of the chain and their esters with glycerides. These compounds provide the ideal energy source needed during hibernation because lipids yield twice the energy yielded by carbohydrates and proteins. Moreover, these fatty acids need very little oxygen in their degradation/conversion to energy.

Blood circulation and homeostasis during hibernation are not well understood. The animal steadies body temperature at around 2°C to 5°C: in mammals the body temperature remains about 1°C above environmental temperature. Usally, when body temperature falls to this level, metabolic rate is increased or the animal awakes, but during hibernation this does not happen. Metabolic rate at 5°C is usually 2-5% of the rate at normal body temperature. For example, the active heart rate of the genus Myotis of bats is between 500 and 700 beats per minute. During hibernation the rate goes down to 20 beats per minute at 5°C, and 8 beats at -7°C. Two consistent and characteristic changes are found in blood during hibernation: an increased production of herapin, which may be contributing to a reduction in the risk of blood clotting during very slow circulation, and an increase in serum magnesium, for which there is no explanation as yet.

Many different types of respiratory patterns have been observed during the state of hibernation. We will mention only one example here: The hedgehog, at a body temperature of 5°C, does not breathe at all for an amazing 56 minutes.

In controlled observations, it has been found that animals which hibernate show improved retention of learned behaviour compared to non-hibernating animals. Again, it is not at all clear why this should be so.

Hibernation is not a prolonged period of constant torpor. There are periodic arousals during winter caused by the accumulation of metabolic end products or having a full bladder. The awakening process is often assisted by shivering, especially when the body temperature is very low. Awakening is a costly process because it takes as much energy to wake up as it does to stay in hibernation for ten days. The ground squirrel, Spermophilus citellus gains around 150-200 g of fat before hibernation. That is more than enough for the energy being used up during sleep; the excess is needed for the wakening up intervals which occur fortnightly.

A number of hypotheses have sought to explain how hibernation is triggered-changes in weather and climate, temperature, humidity and change of diet are among the suggestions. Apart from these causes, a protein was isolated from the blood of a hibernator bear in the USA in the 1980s which, when injected into rats appeared to induce sleeping behaviour in summer. Today it remains uncertain if this protein is the only stimulator of hibernation. If it is, we still need to know what other conditions are related to the protein level and its effect and how the level of protein is maintained at the right level during the animal’s life cycle.

What is already securely known about hibernation establishes it as a truly amazing physiological phenomenon. It tells us that the body temperature of some hibernators will passively adjust ambient tempeature from between 2°C to 32°C without causing awakening. The inevitable question is what advantage such behaviour affords the hibernating animals. Some small animals, because of their high metabolic rates are faced with an acute need for a continuously available supply of food and water. Controlled investigations show that dormant animals at cool temperatures lose much less weight than the non-dormant ones. It has also been shown that small animals can survive for at least a hundred days on the energy derived from ten grams of fat. Hibernation is, in other words, a survival technique, an adaptation to the conditions of poor or non-existent food supply during the winter months.

That is, however, something of a mechanical explanation which, even as a mechanical explanation, is far from satisfactory. The secondary question immediately arises of why this particular adaptation and not another-why not migration, for example, to areas where winter does not affect food supply so drastically? There are many birds and other animals which take this option.

A more satisfying explanation must surely consider what adaptability itself is, how it relates to the variety of life-forms, to the individuation of species and kinds, and to the overwhelming intution (which must touch any truly objective observer) that, at levels of subtlety and intricacy which defy comprehension, the survival and provision of each and every living form is minutely arranged and co-ordinated to create a whole that is thoroughly interconnected. The value of that whole is manifested in many different aspects-beauty, variety, efficiency, the rich warmth of life. Is it not impossible to resist the impression of a wonderful generosity within and behind the world of living forms?