Nocturnality is a behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is " nocturnal ", versus diurnal meaning the opposite.
82-413: See text Aardvarks ( / ˈ ɑːr d v ɑːr k / ARD -vark ; Orycteropus afer ) are medium-sized, burrowing, nocturnal mammals native to Africa. They have a long snout, similar to that of a pig, which is used to sniff out food. Aardvarks are the only living species of the order Tubulidentata , although other prehistoric species and genera of Tubulidentata are known. They are afrotheres ,
164-501: A clade that also includes elephants , manatees , and hyraxes . They are found over much of the southern two-thirds of the African continent, avoiding areas that are mainly rocky. Nocturnal feeders, aardvarks subsist on ants and termites by using their sharp claws and powerful legs to dig the insects out of their hills. Aardvarks also dig to create burrows in which to live and rear their young. Aardvarks are listed as "least concern" by
246-444: A claw and a hoof. Whereas the aardvark is considered digitigrade , it appears at times to be plantigrade . This confusion happens because when it squats it stands on its soles. A contributing characteristic to the burrow digging capabilities of aardvarks is an endosteal tissue called compacted coarse cancellous bone (CCCB). The stress and strain resistance provided by CCCB allows aardvarks to create their burrows, ultimately leading to
328-422: A charm from the heart, skin, forehead, and nails of the aardvark, which they then proceed to pound together with the root of a certain tree. Wrapped in a piece of skin and worn on the chest, the charm is said to give the owner the ability to pass through walls or roofs at night. The charm is said to be used by burglars and those seeking to visit young girls without their parents' permission. Also, some tribes, such as
410-540: A common ancestor who evolved to function as a nocturnal species, decreasing their eyesight in favor of a better sense of smell. The anomaly to this theory were anthropoids , who appeared to have the most divergence from nocturnality of all organisms examined. While most mammals did not exhibit the morphological characteristics expected of a nocturnal creature, reptiles and birds fit in perfectly. A larger cornea and pupil correlated well with whether these two classes of organisms were nocturnal or not. Being active at night
492-485: A decrease in mate calls and continued to move around instead of waiting for a potential mate to arrive. This hurts the overall fitness of the species, which is concerning considering the overall decrease in amphibian populations. Predation Some nocturnal predator-prey relationships are interrupted by artificial lighting. Bats that are fast-moving are often at an advantage with insects being drawn to light; they are fast enough to escape any predators also attracted to
574-471: A drought. Aardvarks that survive droughts can take long periods of time to regain health and optimal thermoregulatory physiology, reducing the reproductive potential of the species. Aardvarks handle captivity well. The first zoo to have one was London Zoo in 1869, which had an animal from South Africa . In African folklore , the aardvark is much admired because of its diligent quest for food and its fearless response to soldier ants . Hausa magicians make
656-427: A favourable environment for plants and a variety of animals. Digging is also facilitated by its forearm's unusually stout ulna and radius. An aardvark's weight is typically between 60 and 80 kilograms (130–180 lb). An aardvark's length is usually between 105 and 130 centimetres (3.44–4.27 ft), and can reach lengths of 2.2 metres (7 ft 3 in) when its tail (which can be up to 70 centimetres (28 in))
738-418: A major effect on nocturnal animals, as well as diurnal species. The causes of these can be traced to distinct, sometimes overlapping areas: light pollution and spatial disturbance. Light pollution is a major issue for nocturnal species, and the impact continues to increase as electricity reaches parts of the world that previously had no access. Species in the tropics are generally more affected by this due to
820-441: A means to explore their location. When a concentration of ants or termites is detected, the aardvark digs into it with its powerful front legs, keeping its long ears upright to listen for predators, and takes up an astonishing number of insects with its long, sticky tongue—as many as 50,000 in one night have been recorded. Its claws enable it to dig through the extremely hard crust of a termite or ant mound quickly. It avoids inhaling
902-435: A muscular pyloric area that acts as a gizzard to grind swallowed food up, thereby rendering chewing unnecessary. Its cecum is large. Both sexes emit a strong smelling secretion from an anal gland. Its salivary glands are highly developed and almost completely ring the neck; their output is what causes the tongue to maintain its tackiness. The female has two pairs of teats in the inguinal region. Genetically speaking,
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#1732848002440984-454: A night. Aardvarks shift their circadian rhythms to more diurnal activity patterns in response to a reduced food supply. This survival tactic may signify an increased risk of imminent mortality. The aardvark is a rather quiet animal. However, it does make soft grunting sounds as it forages and loud grunts as it makes for its tunnel entrance. It makes a bleating sound if frightened. When it is threatened it will make for one of its burrows. If one
1066-495: A number of threats to the different endangered species. Adults are likely to stay away from artificially lit beaches that they might prefer to lay eggs on, as there is less cover against predators. Additionally, baby sea turtles that hatch from eggs on artificially lit beaches often get lost, heading towards the light sources as opposed to the ocean. Rhythmic behaviors are affected by light pollution both seasonally and daily patterns. Migrating birds or mammals might have issues with
1148-597: A person to enter. The aardvark changes the layout of its home burrow regularly, and periodically moves on and makes a new one. The old burrows are an important part of the African wildlife scene. As they are vacated, then they are inhabited by smaller animals like the African wild dog , ant-eating chat , Nycteris thebaica and warthogs . Other animals that use them are hares, mongooses, hyenas, owls, pythons, and lizards. Without these refuges many animals would die during wildfire season. Only mothers and young share burrows; however,
1230-470: A relatively similar spatial habitat as they did before. In comparison, herbivorous prey tend to stay in areas where human disturbance is low, limiting both resources and their spatial habitat. This leads to an imbalance in favor of predators, who increase in population and come out more often at night. In zoos , nocturnal animals are usually kept in special night-illumination enclosures to invert their normal sleep-wake cycle and to keep them active during
1312-1053: A very low level employing ordnance that could penetrate deep into the ground. In the US Navy, the squadron VF-114 was nicknamed the Aardvarks, flying F-4s and then F-14s . The squadron mascot was adapted from the animal in the comic strip B.C. , which the F-4 was said to resemble. Cerebus the Aardvark is a 300-issue comic book series by Dave Sim. Nocturnal Nocturnal creatures generally have highly developed senses of hearing , smell , and specially adapted eyesight . Some animals, such as cats and ferrets , have eyes that can adapt to both low-level and bright day levels of illumination (see metaturnal ). Others, such as bushbabies and (some) bats , can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison with their body size to compensate for
1394-421: Is nocturnal and is a solitary creature that feeds almost exclusively on ants and termites ( myrmecophagy ); the only fruit eaten by aardvarks is the aardvark cucumber . In fact, the cucumber and the aardvark have a symbiotic relationship as they eat the subterranean fruit, then defecate the seeds near their burrows, which then grow rapidly due to the loose soil and fertile nature of the area. The time spent in
1476-698: Is pollination - nocturnal pollinators such as moths, beetles, thrips, and bats have a lower risk of being seen by predators, and the plants evolved temporal scent production and ambient heat to attract nocturnal pollination. Like with predators hunting the same prey, some plants such as apples can be pollinated both during the day and at night. Nocturnality is a form of crypsis , an adaptation to avoid or enhance predation . Although lions are cathemeral , and may be active at any time of day or night, they prefer to hunt at night because many of their prey species ( zebra , antelope , impala, wildebeest , etc.) have poor night vision . Many species of small rodents, such as
1558-424: Is a mammal belonging to any species within the afrotherian family Tenrecidae , which is endemic to Madagascar . Tenrecs are a very diverse group; as a result of convergent evolution , some resemble hedgehogs , shrews , opossums , rats , and mice . They occupy aquatic , arboreal , terrestrial , and fossorial environments. Some of these species, including the greater hedgehog tenrec , can be found in
1640-450: Is a form of niche differentiation , where a species' niche is partitioned not by the amount of resources but by the amount of time (i.e. temporal division of the ecological niche ). Hawks and owls can hunt the same field or meadow for the same rodents without conflict because hawks are diurnal and owls are nocturnal. This means they are not in competition for each other's prey. Another niche that being nocturnal lessens competition within
1722-417: Is able to leave the burrow to accompany its mother after only two weeks and eats termites at 9 weeks, and is weaned between three months and 16 weeks. At six months of age, it is able to dig its own burrows, but it will often remain with the mother until the next mating season , and is sexually mature from approximately two years of age. Aardvarks were thought to have declining numbers, however, this
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#17328480024401804-410: Is avoiding the heat of the day. This is especially true in arid biomes like deserts , where nocturnal behavior prevents creatures from losing precious water during the hot, dry daytime. This is an adaptation that enhances osmoregulation . One of the reasons that ( cathemeral ) lions prefer to hunt at night is to conserve water. Hamiltons Frog , found on Stephens and Maud islands, stays hidden for
1886-554: Is borrowed, via French , from the Malagasy word tandraka (variant of trandraka ), which refers to the tailless tenrec ( Tenrec ecaudatus ); it has been speculated that the Malagasy word is related to Malay : landak , lit. ' porcupine '. Tenrecs are believed to have evolved from a single species that colonized Madagascar between 42 and 25 million years ago. The question of how this family reached Madagascar
1968-485: Is difficult to obtain (as it is not sold in shops or markets) and difficult to prepare correctly. The lesser hedgehog tenrec ( Echinops telfairi ) is one of 16 mammalian species that will have its genome sequenced as part of the Mammalian Genome Project . It is increasingly popular in the pet trade, and in the future may serve as an important model organism in biomedicine, as it is only distantly related to
2050-412: Is made up of more turbinate bones than any other mammal, with between 9 and 11, compared to dogs with 4 to 5. With a large quantity of turbinate bones, the aardvark has more space for the moist epithelium , which is the location of the olfactory bulb. The nose contains nine olfactory bulbs , more than any other mammal. Its keen sense of smell is not just from the quantity of bulbs in the nose but also in
2132-443: Is negatively affecting tenrec species that inhabit forests. Five of the six threatened Tenrec species are dependent on forest habitats. As of 2022, conservation of the tenrec population is not being prioritized. Because most tenrecs are dependent on forest habitats, conservation efforts would need to include a focus on reduction in deforestation on Madagascar as well as habitat restoration. Current conservation efforts include that of
2214-701: Is not close it will dig a new one rapidly. This new one will be short and require the aardvark to back out when the coast is clear. The aardvark is known to be a good swimmer and has been witnessed successfully swimming in strong currents. It can dig a yard of tunnel in about five minutes, but otherwise moves fairly slowly. When leaving the burrow at night, they pause at the entrance for about ten minutes, sniffing and listening. After this period of watchfulness, it will bound out and within seconds it will be 10 metres (33 ft) away. It will then pause, prick its ears, twisting its head to listen, then jump and move off to start foraging. Aside from digging out ants and termites,
2296-484: Is not closely related to the South American anteater , despite sharing some characteristics and a superficial resemblance. The similarities are the outcome of convergent evolution . The closest living relatives of the aardvark are the elephant shrews , tenrecidae , and golden moles . Along with sirenians , hyraxes , elephants , and their extinct relatives, these animals form the superorder Afrotheria . Studies of
2378-429: Is not needed anymore due to the evolution of compensatory sensory systems, such as a heightened sense of smell and more astute auditory systems. In a recent study, recently extinct elephant birds and modern day nocturnal kiwi bird skulls were examined to recreate their likely brain and skull formation. They indicated that olfactory bulbs were much larger in comparison to their optic lobes , indicating they both have
2460-514: Is possibly because they are not readily seen. There are no definitive counts because of their nocturnal and secretive habits; however, their numbers seem to be stable overall. They are not considered common anywhere in Africa, but due to their large range, they maintain sufficient numbers. There may be a slight decrease in numbers in eastern, northern, and western Africa. Southern African numbers are not decreasing. It has received an official designation from
2542-496: Is still unresolved, but the leading hypothesis suggests a small number of individuals may have found themselves on floating vegetation and crossed the Mozambique Channel , which separates Madagascar from southeastern Africa. The Tenrecidae family is one of only four extant terrestrial mammal lineages to have colonized and diversified on Madagascar. Once established on Madagascar, tenrecs diversified to occupy various niches on
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2624-472: Is taken into account. It is 60 centimetres (24 in) tall at the shoulder, and has a girth of about 100 centimetres (3.3 ft). It is the largest member of the proposed clade Afroinsectiphilia . The aardvark is pale yellowish-grey in colour and often stained reddish-brown by soil . The aardvark's coat is thin, and the animal's primary protection is its tough skin. Its hair is short on its head and tail; however its legs tend to have longer hair. The hair on
2706-476: Is usually depicted with the head of an unidentified animal , whose similarity to an aardvark has been noted in scholarship. The titular character and his families from Arthur , an animated television series for children based on a book series and produced by WGBH , shown in more than 180 countries, is an aardvark. In the first book of the series, Arthur's Nose (1976), he has a long, aardvark-like nose, but in later books, his face becomes more rounded. Otis
2788-447: Is vaguely pig-like in appearance. Its body is stout with a prominently arched back and is sparsely covered with coarse hairs. The limbs are of moderate length, with the rear legs being longer than the forelegs. The front feet have lost the pollex (or 'thumb'), resulting in four toes, while the rear feet have all five toes. Each toe bears a large, robust nail which is somewhat flattened and shovel-like, and appears to be intermediate between
2870-651: The IUCN , although their numbers are decreasing. The aardvark is sometimes colloquially called the "African ant bear", "anteater" (not to be confused with the South American anteaters ), or the "Cape anteater" after the Cape of Good Hope . The name "aardvark" is Afrikaans ( pronounced [ˈɑːrtfark] ) and comes from earlier Afrikaans erdvark . It means "earth pig " or "ground pig" ( aarde : ' earth ' , vark : ' pig, young pig ' ), because of its burrowing habits. The name Orycteropus means "burrowing foot", and
2952-471: The Large Japanese Field Mouse , are active at night because most of the dozen or so birds of prey that hunt them are diurnal. There are many diurnal species that exhibit some nocturnal behaviors. For example, many seabirds and sea turtles only gather at breeding sites or colonies at night to reduce the risk of predation to themselves and/or their offspring. Nocturnal species take advantage of
3034-455: The Madagascar dry deciduous forests . However, the speciation rate in this group has been higher in humid forests . All tenrecs are believed to descend from a common ancestor that lived 29–37 million years ago after rafting over from Africa . The split from their closest relatives, African otter shrews , is estimated to have occurred about 47–53 million years ago. The word tenrec
3116-506: The Margbetu , Ayanda , and Logo , will use aardvark teeth to make bracelets, which are regarded as good luck charms. The meat, which has a resemblance to pork, is eaten in certain cultures. In the mythology of the Dagbon people of Ghana, the aardvark is believed to possess superpowers. The Dagombas believe this animal can transfigure into and interact with humans. The ancient Egyptian god Set
3198-459: The Mesozoic , many ancestors of modern-day mammals evolved nocturnal characteristics in order to avoid contact with the numerous diurnal predators. A recent study attempts to answer the question as to why so many modern day mammals retain these nocturnal characteristics even though they are not active at night. The leading answer is that the high visual acuity that comes with diurnal characteristics
3280-454: The otter shrews have just two young per litter, the tailless tenrec can have as many as 32, and females possess up to 29 teats , more than any other mammal. Some tenrec species are social, living in multigenerational family groups with over a dozen individuals. In the island nation of Mauritius , and also on the Comoran island of Mayotte , some of the inhabitants eat tenrec meat, although it
3362-431: The otter shrews , and after that other African insectivorous mammals including golden moles and elephant shrews . The common ancestry of these animals, which are classified together in the clade Afrotheria , was not recognized until the late 1990s. Continuing work on the molecular and morphological diversity of afrotherian mammals has provided ever increasing support for their common ancestry. Tenrecs are among
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3444-455: The Aardvark was a puppet character used on Children's BBC programming. An aardvark features as the antagonist in the cartoon The Ant and the Aardvark as well as in the Canadian animated series The Raccoons . The supersonic fighter-bomber F-111/FB-111 was nicknamed the Aardvark because of its long nose resembling the animal. It also had similarities with its nocturnal missions flown at
3526-452: The IUCN as least concern . However, they are a species in a precarious situation, as they are so dependent on such specific food; therefore if a problem arises with the abundance of termites, the species as a whole would be affected drastically. Recent research suggests that aardvarks may be particularly vulnerable to alterations in temperature caused by climate change. Droughts negatively impact
3608-460: The aardvark also excavates burrows in which to live, which generally fall into one of three categories: burrows made while foraging, refuge and resting location, and permanent homes. Temporary sites are scattered around the home range and are used as refuges, while the main burrow is also used for breeding. Main burrows can be deep and extensive, have several entrances and can be as long as 13 metres (43 ft). These burrows can be large enough for
3690-470: The aardvark contains many unique and different features. One of the most distinctive characteristics of the Tubulidentata is their teeth . Instead of having a pulp cavity , each tooth has a cluster of thin, hexagonal, upright, parallel tubes of vasodentin (a modified form of dentine ), with individual pulp canals, held together by cementum . The number of columns is dependent on the size of the tooth, with
3772-415: The aardvark is a living fossil , as its chromosomes are highly conserved, reflecting much of the early eutherian arrangement before the divergence of the major modern taxa . Aardvarks are found in sub-Saharan Africa , where suitable habitat ( savannas , grasslands , woodlands and bushland ) and food (i.e., ants and termites ) is available. They spend the daylight hours in dark burrows to avoid
3854-401: The aardvark is another unique area, as it contains ten nasal conchae , more than any other placental mammal. The sides of the nostrils are thick with hair. The tip of the snout is highly mobile and is moved by modified mimetic muscles . The fleshy dividing tissue between its nostrils probably has sensory functions, but it is uncertain whether they are olfactory or vibratory in nature. Its nose
3936-447: The aardvark is known to live in small family groups or as a solitary creature. If attacked in the tunnel, it will escape by digging out of the tunnel thereby placing the fresh fill between it and its predator, or if it decides to fight it will roll onto its back, and attack with its claws. The aardvark has been known to sleep in a recently excavated ant nest, which also serves as protection from its predators . Aardvarks pair only during
4018-442: The aardvark will keep its nose to the ground and its ears pointed forward, which indicates that both smell and hearing are involved in the search for food. They zig-zag as they forage and will usually not repeat a route for 5–8 days as they appear to allow time for the termite nests to recover before feeding on it again. During a foraging period, they will stop to dig a V-shaped trench with their forefeet and then sniff it profusely as
4100-408: The artificial lighting. Insects are the most obvious example, who are attracted by the lighting and are usually killed by either the heat or electrical current. Some species of frogs are blinded by the quick changes in light, while nocturnal migratory birds may be disoriented, causing them to lose direction, tire out, or be captured by predators. Sea turtles are particularly affected by this, adding to
4182-473: The availability of termites and ants, which comprise the bulk of an aardvark's diet. Nocturnal species faced with resource scarcity may increase their diurnal activity to spare the energy costs of staying warm at night, but this comes at the cost of withstanding high temperatures during the day. A study on aardvarks in the Kalahari Desert saw that five out of six aardvarks being studied perished following
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#17328480024404264-553: The brain have shown the similarities with Condylarthra . Based on his study of fossils, Bryan Patterson has concluded that early relatives of the aardvark appeared in Africa around the end of the Paleocene . The ptolemaiidans , a mysterious clade of mammals with uncertain affinities, may actually be stem-aardvarks, either as a sister clade to Tubulidentata or as a grade leading to true tubulidentates. The first unambiguous tubulidentate
4346-401: The breeding season; after a gestation period of seven months, one cub weighing around 1.7–1.9 kilograms (3.7–4.2 lb) is born during May–July. When born, the young has flaccid ears and many wrinkles. When nursing, it will nurse off each teat in succession. After two weeks, the folds of skin disappear and after three, the ears can be held upright. After 5–6 weeks, body hair starts growing. It
4428-428: The change in their relatively constant light patterns, but temperate species relying on day-night triggers for behavioral patterns are also affected as well. Many diurnal species see the benefit of a "longer day", allowing for a longer hunting period which is detrimental to their nocturnal prey trying to avoid them. Light pollution can disorient species that are used to darkness, as their adaptive eyes are not as used to
4510-801: The coastal areas of Namibia , Ivory Coast , and Ghana . They are not found in Madagascar. Aardvarks live for up to 23 years in captivity . Its keen hearing warns it of predators: lions , leopards , cheetahs, African wild dogs , hyenas , and pythons . Some humans also hunt aardvarks for meat. Aardvarks can dig fast or run in zigzag fashion to elude enemies, but if all else fails, they will strike with their claws, tail and shoulders, sometimes flipping onto their backs lying motionless except to lash out with all four feet. They are capable of causing substantial damage to unprotected areas of an attacker. They will also dig to escape as they can. Sometimes, when pressed, aardvarks can dig extremely quickly. The aardvark
4592-428: The cost. The increasing amount of habitat destruction worldwide as a result of human expansion has given both advantages and disadvantages to different nocturnal animals. As a result of peak human activity in the daytime, more species are likely to be active at night in order to avoid the new disturbance in their habitat. Carnivorous predators however are less timid of the disturbance, feeding on human waste and keeping
4674-399: The daytime. Crepuscular species, such as rabbits , skunks , tigers and hyenas , are often erroneously referred to as nocturnal. Cathemeral species, such as fossas and lions , are active both in the day and at night. While it is difficult to say which came first, nocturnality or diurnality, a hypothesis in evolutionary biology , the nocturnal bottleneck theory, postulates that in
4756-573: The development of the brain, as its olfactory lobe is very developed. The snout resembles an elongated pig snout. The mouth is small and tubular, typical of species that feed on ants and termites . The aardvark has a long, thin, snakelike, protruding tongue (as much as 30 centimetres (12 in) long) and elaborate structures supporting a keen sense of smell . The ears, which are very effective, are disproportionately long, about 20–25 centimetres (7.9–9.8 in) long. The eyes are small for its head, and consist only of rods . The aardvark's stomach has
4838-429: The dust by sealing the nostrils. When successful, the aardvark's long (up to 30 centimetres (12 in)) tongue licks up the insects; the termites' biting, or the ants' stinging attacks are rendered futile by the tough skin. After an aardvark visit at a termite mound, other animals will visit to pick up all the leftovers. Termite mounds alone do not provide enough food for the aardvark, so they look for termites that are on
4920-428: The early Miocene of Kenya show close affinities to living species from Madagascar, such as Geogale aurita . Most species are nocturnal and have poor eyesight. Their other senses are well developed, however and they have especially sensitive whiskers . As with many of their other features, the dental formula of tenrecs varies greatly between species; they can have from 32 to 42 teeth in total. Unusual for mammals,
5002-476: The few terrestrial mammals that echolocate . Unusual among placental mammals , the rectum and urogenital tracts of tenrecs share a common opening, or cloaca which is a feature more commonly seen in birds , reptiles , and amphibians . They have a low body temperature , sufficiently low that they do not require a scrotum to cool their sperm as do most other mammals. All species appear to be at least somewhat omnivorous , with invertebrates forming
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#17328480024405084-422: The first portion of night (roughly the four hours between 8:00 p.m. and 12:00 a.m.); however, they do not seem to prefer bright or dark nights over the other. During adverse weather or if disturbed they will retreat to their burrow systems. They cover between 2 and 5 kilometres (1.2 and 3.1 mi) per night; however, some studies have shown that they may traverse as far as 30 kilometres (19 mi) in
5166-459: The heat of the day. The only major habitat that they are not present in is swamp forest, as the high water table precludes digging to a sufficient depth. They also avoid terrain rocky enough to cause problems with digging. They have been documented as high as 3,200 metres (10,500 ft) in Ethiopia. They are present throughout sub-Saharan Africa all the way to South Africa with few exceptions including
5248-595: The hours when visitors will be there to see them. Hedgehogs and sugar gliders are just two of the many nocturnal species kept as ( exotic ) pets. Cats have adapted to domestication so that each individual, whether stray alley cat or pampered housecat, can change their activity level at will, becoming nocturnal or diurnal in response to their environment or the routine of their owners. Cats normally demonstrate crepuscular behavior, bordering nocturnal, being most active in hunting and exploration at dusk and dawn. Tenrec A tenrec ( / ˈ t ɛ n r ɛ k / )
5330-464: The intestine of the aardvark helps the fertility of the seed, and the fruit provides needed moisture for the aardvark. They avoid eating the African driver ant and red ants. Due to their stringent diet requirements, they require a large range to survive. An aardvark emerges from its burrow in the late afternoon or shortly after sunset, and forages over a considerable home range encompassing 10 to 30 kilometres (6.2 to 18.6 mi). While foraging for food,
5412-548: The island. Many evolved resemblances to familiar but unrelated mammals that are not found on Madagascar. For instance, the two species of hedgehog tenrec possess coats of hardened spines and the ability to roll into a ball when threatened, characteristics similar to those of true hedgehogs . This example, along with others, demonstrates convergent evolution; it has provided evolutionary biologists with opportunities to study adaptation over evolutionary timescales. Tenrecs are small mammals of variable body form. The smallest species are
5494-504: The largest having about 1,500. The teeth have no enamel coating and are worn away and regrow continuously. The aardvark is born with conventional incisors and canines at the front of the jaw, which fall out and are not replaced. Adult aardvarks have only cheek teeth at the back of the jaw , and have a dental formula of: 0.0.2-3.3 0.0.2.3 These remaining teeth are peg-like and rootless and are of unique composition. The teeth consist of 14 upper and 12 lower jaw molars. The nasal area of
5576-412: The largest part of their diets. One species, Microgale mergulus , is semiaquatic (similar to the lifestyle of their closest relatives, the otter shrews). All of the species, semiaquatic or not, appear to have evolved from a single, common ancestor with the otter shrews comprising the next, most-closely related mammalian species. While the fossil record of tenrecs is scarce, at least some specimens from
5658-399: The light, leaving slow-moving bats at a disadvantage. Another example is harbor seals eating juvenile salmon that moved down a river lit by nearby artificial lighting. Once the lights were turned off, predation levels decreased. Many diurnal prey species forced into being nocturnal are susceptible to nocturnal predators and those species with poor nocturnal eyesight often bear the brunt of
5740-424: The lower light levels at night. More specifically, they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their visual sensitivity : in the low-light conditions. Nocturnality helps wasps , such as Apoica flavissima , avoid hunting in intense sunlight. Diurnal animals, including humans (except for night owls ), squirrels and songbirds, are active during
5822-399: The majority of its body is grouped in clusters of 3–4 hairs. The hair surrounding its nostrils is dense to help filter particulate matter out as it digs. Its tail is very thick at the base and gradually tapers. The greatly elongated head is set on a short, thick neck, and the end of the snout bears a disc, which houses the nostrils. It contains a thin but complete zygomatic arch . The head of
5904-408: The majority of the day when temperatures are warmer and are mainly active at night. They will only come out during the day if there are humid and cool conditions. Many plant species native to arid biomes have adapted so that their flowers only open at night when the sun's intense heat cannot wither and destroy their moist, delicate blossoms. These flowers are pollinated by bats, another creature of
5986-692: The mice, rats, guinea pigs, and rhesus macaques which comprise the most common research animals. Of the 31 species assessed, 24 (77%) are categorized by the IUCN Red List as Least Concern, 1 species as Data Deficient, 4 species as Vulnerable, and 2 species as Endangered. The conservation status of many tenrec species is of concern due to an increase of threats within the last 50 years. The main threats facing tenrecs include habitat loss due to deforestation , fragmentation and degradation, hunting, incidental capture, and climate change . Slash-and-burn agriculture, as well as commercial logging and mining of metals
6068-485: The move. When these insects move, they can form columns 10–40 metres (33–131 ft) long and these tend to provide easy pickings with little effort exerted by the aardvark. These columns are more common in areas of livestock or other hoofed animals. The trampled grass and dung attract termites from the Odontotermes , Microtermes , and Pseudacanthotermes genera. On a nightly basis they tend to be more active during
6150-428: The name afer refers to Africa. The name of the aardvark's order, Tubulidentata, comes from the tubule-style teeth. The aardvark is not closely related to the pig; rather, it is the sole extant representative of the obscure mammalian order Tubulidentata , in which it is usually considered to form one variable species of the genus Orycteropus , the sole surviving genus in the family Orycteropodidae . The aardvark
6232-428: The night time to prey on species that are used to avoiding diurnal predators. Some nocturnal fish species will use the moonlight to prey on zooplankton species that come to the surface at night. Some species have developed unique adaptations that allow them to hunt in the dark. Bats are famous for using echolocation to hunt down their prey, using sonar sounds to capture them in the dark. Another reason for nocturnality
6314-428: The night. Climate-change and the change in global temperatures has led to an increasing amount of diurnal species to push their activity patterns closer towards crepuscular or fully nocturnal behavior. This adaptive measure allows species to avoid the heat of the day, without having to leave that particular habitat. The exponential increase in human expansion and technological advances in the last few centuries has had
6396-429: The permanent dentition in tenrecs tends not to completely erupt until well after adult body size has been reached. This is one of several anatomical features shared by elephants, hyraxes , sengis , and golden moles (but apparently not aardvarks ), consistent with their descent from a common ancestor. Tenrecs have a gestation period of 50 to 64 days, and give birth to a number of relatively undeveloped young. While
6478-411: The size of shrews, with a body length of around 4.5 cm (1.8 in), and weighing just 5 g (0.18 oz), while the largest, the common or tailless tenrec , is 25 to 39 cm (9.8 to 15.4 in) in length, and can weigh over 1 kilogram (2.2 lb). Although they may resemble shrews, hedgehogs, or opossums, they are not closely related to any of these groups, their closest relatives being
6560-704: The timing of their movement for example. On a day-to-day basis, species can see significant changes in their internal temperatures, their general movement, feeding and body mass. These small scale changes can eventually lead to a population decline, as well as hurting local trophic levels and interconnecting species. Some typically diurnal species have even become crepuscular or nocturnal as a result of light pollution and general human disturbance. There have been documented effects of light pollution on reproductive cycles and factors in different species. It can affect mate choice , migration to breeding grounds, and nest site selection. In male green frogs , artificial light causes
6642-642: Was originally thought to be a tubulidentate that was descended from ancestors that entered the island during the Eocene . However, a number of subtle anatomical differences coupled with recent molecular evidence now lead researchers to believe that Plesiorycteropus is a relative of golden moles and tenrecs that achieved an aardvark-like appearance and ecological niche through convergent evolution. The aardvark has seventeen poorly defined subspecies listed: The 1911 Encyclopædia Britannica also mentions O. a. capensis or Cape ant-bear from South Africa. The aardvark
6724-600: Was probably Myorycteropus africanus from Kenyan Miocene deposits. The earliest example from the genus Orycteropus was Orycteropus mauritanicus , found in Algeria in deposits from the middle Miocene, with an equally old version found in Kenya. Fossils from the aardvark have been dated to 5 million years, and have been located throughout Europe and the Near East . The mysterious Pleistocene Plesiorycteropus from Madagascar
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