Misplaced Pages

#317682

49-566: See text A pika ( / ˈ p aɪ k ə / PEYE -kə or / ˈ p iː k ə / PEE -kə ) is a small, mountain-dwelling mammal native to Asia and North America. With short limbs, a very round body, an even coat of fur, and no external tail, they resemble their close relative, the rabbit , but with short, rounded ears. The large-eared pika of the Himalayas and nearby mountains lives at elevations of more than 6,000 m (20,000 ft). The name "pika" appears to be derived from

98-601: A "haypile" of cached plants. The impact of human activity on the tundra ecosystems where pikas live has been recorded dating back to the 1970s. Rather than hibernate during winter, pikas forage for grasses and other forms of plant matter and stash these findings in protected dens in a process called "haying". They eat the dried plants during the winter. When pikas mistake humans as predators, they may respond to humans as they do to other species that do prey on pikas. Such interactions with humans have been linked to pikas having reduced amounts of foraging time, consequentially limiting

147-533: A gestation is called the gestation period . In obstetrics , gestational age refers to the time since the onset of the last menses , which on average is fertilization age plus two weeks. In mammals, pregnancy begins when a zygote (fertilized ovum) implants in the female's uterus and ends once the fetus leaves the uterus during labor or an abortion (whether induced or spontaneous). In humans, pregnancy can be defined clinically, biochemically or biologically. Clinically, pregnancy starts from first day of

196-424: A way to attract potential mates. There are also different calls depending on the season. In the spring the songs become more frequent during the breeding season. In late summer the vocalizations become short calls. Through various studies, the acoustic characteristics of the vocalizations can be a useful taxonomic tool. The average lifespan of pikas in the wild is roughly seven years. A pika's age may be determined by

245-476: A wide variety of plant matter, including forbs , grasses , sedges , shrub twigs, moss and lichens. Easily digestible food is processed in the gastrointestinal tract and expelled as regular feces. But in order to get nutrients out of hard to digest fiber, pika ferment fiber in the cecum (in the GI tract) and then expel the contents as cecotropes , which are reingested ( cecotrophy ). The cecotropes are then absorbed in

294-572: Is Desmatolagus (middle Eocene to Miocene, 42.5–14.8 Ma), usually included in the Ochotonidae, sometimes in Leporidae or in neither ochotonid nor leporid stem- lagomorphs . Ochotonids appeared in Asia between the late Eocene and the early Oligocene, and continued to develop along with increased distribution of C 3 grasses in previously forest dominated areas under the "climatic optimum" from

343-675: Is a vertebrate animal of the class Mammalia ( / m ə ˈ m eɪ l i . ə / ). Mammals are characterized by the presence of milk -producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair , and three middle ear bones . These characteristics distinguish them from reptiles and birds , from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 27 orders . The largest orders of mammals, by number of species , are

392-470: Is a gradual physiological increase in senescence in the maternal decidua (the specialized layer of endometrium that forms the base of the placental bed) and in placental cells. This increase in senescence is associated with a gradual physiological increase in DNA damage during gestation. A positive correlation between the gestation period and maximum lifespan was observed across 740 mammalian species. It

441-401: Is called placental viviparity ; mammals are the best example, but it has also evolved independently in other animals, such as in scorpions , some sharks , and in velvet worms . Viviparous offspring live independently and require an external food supply from birth. Certain lizards also employ this method such as the genera Tiliqua and Corucia . The placenta is attached directly to

490-579: Is characterized by archaic ( plesiomorphic ) cheek teeth and small size. The North American species migrated from Eurasia. They invaded the New World twice: Ochotona cf. whartoni and small pikas of the O. pusilla group are also known from Siberia. The extant, endemic North American species appeared in the Pleistocene. The North American collared pika ( O. collaris ) and American pika ( O. princeps ) have been suggested to have descended from

539-497: Is extant within the family, covering 37 species , though many fossil genera are known. Another species, the Sardinian pika , belonging to the separate genus Prolagus , has become extinct within the last 2000 years owing to human activity. Pikas prefer rocky slopes and graze on a range of plants, primarily grasses, flowers, and young stems. In the autumn they pull hay, soft twigs, and other stores of food under rocks to eat during

SECTION 10

#1732787081318

588-500: Is important for the maintenance of a healthy pregnancy and surveillance of related complications. In high-income countries, prenatal care typically involves monthly visits during the first two trimesters, with an increasing number of visits closer to delivery. At these visits, healthcare providers will evaluate a variety of parental and fetal metrics, including fetal growth and heart rate, birth defects , maternal blood pressure, among others. After birth, health care providers will measure

637-572: Is primarily driven by human poaching and habitat destruction , primarily deforestation . Over 70% of mammal species are in the orders Rodentia , Chiroptera , and Eulipotyphla . Mammal classification has been through several revisions since Carl Linnaeus initially defined the class, and at present , no classification system is universally accepted. McKenna & Bell (1997) and Wilson & Reeder (2005) provide useful recent compendiums. Simpson (1945) provides systematics of mammal origins and relationships that had been taught universally until

686-572: Is that the bottom of their paws are covered with fur and lack paw pads. Rock-dwelling pikas have small litters of fewer than five young, whilst the burrowing species tend to give birth to more young and to breed more frequently, possibly owing to a greater availability of resources in their native habitats. The young are born altricial (eyes and ears closed, no fur) after a gestation period of between 25 and 30 days. Pikas are active during daylight ( diurnal ) or twilight hours ( crepuscular ), with higher-elevation species generally being more active during

735-426: Is the viviparous placental mammals , so named for the temporary organ ( placenta ) used by offspring to draw nutrition from the mother during gestation . Most mammals are intelligent , with some possessing large brains, self-awareness , and tool use . Mammals can communicate and vocalize in several ways, including the production of ultrasound , scent marking , alarm signals , singing , echolocation ; and, in

784-473: The Cretaceous . The relationships between these three lineages is contentious, and all three possible hypotheses have been proposed with respect to which group is basal . These hypotheses are Atlantogenata (basal Boreoeutheria), Epitheria (basal Xenarthra) and Exafroplacentalia (basal Afrotheria). Boreoeutheria in turn contains two major lineages— Euarchontoglires and Laurasiatheria . Estimates for

833-564: The International Union for Conservation of Nature (IUCN) completed a five-year Global Mammal Assessment for its IUCN Red List , which counted 5,488 species. According to research published in the Journal of Mammalogy in 2018, the number of recognized mammal species is 6,495, including 96 recently extinct. The word " mammal " is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from

882-556: The Latin mamma ("teat, pap"). In an influential 1988 paper, Timothy Rowe defined Mammalia phylogenetically as the crown group of mammals, the clade consisting of the most recent common ancestor of living monotremes ( echidnas and platypuses ) and therian mammals ( marsupials and placentals ) and all descendants of that ancestor. Since this ancestor lived in the Jurassic period, Rowe's definition excludes all animals from

931-658: The Tungus pika , and the scientific name Ochotona is derived from the Mongolian word ogotno, оготно , which means pika. It is used for any member of the Ochotonidae ( / ɒ k ə t oʊ n ɪ d eɪ / ), a family within the order of lagomorphs , the order which also includes the Leporidae (rabbits and hares ). They are the smallest animal in the lagomorph group. Only one genus , Ochotona ( / ɒ k ə ˈ t oʊ n ə / or / ɒ tʃ ə ˈ t oʊ n ə / ),

980-606: The biological classification scheme used, are the primates : apes , monkeys , and lemurs ; the Cetartiodactyla : whales and even-toed ungulates ; and the Carnivora which includes cats , dogs , weasels , bears , seals , and allies. According to Mammal Species of the World , 5,416 species were identified in 2006. These were grouped into 1,229  genera , 153  families and 29 orders. In 2008,

1029-406: The dominant terrestrial animal group from 66 million years ago to the present. The basic mammalian body type is quadrupedal , with most mammals using four limbs for terrestrial locomotion ; but in some, the limbs are adapted for life at sea , in the air , in trees or underground . The bipeds have adapted to move using only the two lower limbs, while the rear limbs of cetaceans and

SECTION 20

#1732787081318

1078-428: The rodents , bats , and Eulipotyphla (including hedgehogs , moles and shrews ). The next three are the primates (including humans , monkeys and lemurs ), the even-toed ungulates (including pigs , camels , and whales ), and the Carnivora (including cats , dogs , and seals ). Mammals are the only living members of Synapsida ; this clade , together with Sauropsida (reptiles and birds), constitutes

1127-439: The sea cows are mere internal vestiges . Mammals range in size from the 30–40 millimetres (1.2–1.6 in) bumblebee bat to the 30 metres (98 ft) blue whale —possibly the largest animal to have ever lived. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale . All modern mammals give birth to live young, except the five species of monotremes , which lay eggs. The most species-rich group

1176-400: The 13th week, the second trimester is 14th–28/29th week, and the third trimester is 29/30th–42nd week. Birth normally occurs at a gestational age of about 40 weeks, though it is common for births to occur from 37 to 42 weeks. Labor occurring prior to 37 weeks gestation is considered preterm labor and can result from multiple factors, including previous preterm deliveries. Prenatal care

1225-904: The Asiatic extant northern pika O. hyperborea in one location in the middle Pleistocene United States. While Ochotona is the only currently living genus of Ochotonidae, extinct genera of ochotonids include † Albertona , † Alloptox , † Amphilagus , † Australagomys , † Austrolagomys , † Bellatona , † Bellatonoides , † Bohlinotona , † Cuyamalagus , † Desmatolagus , † Eurolagus , † Gripholagomys , † Gymnesicolagus , † Hesperolagomys , † Heterolagus , † Kenyalagomys , † Lagopsis , † Marcuinomys , † Ochotonoides , † Ochotonoma , † Oklahomalagus , † Oreolagus , † Paludotona , † Piezodus , † Plicalagus , † Pliolagomys , † Prolagus , † Proochotona ( syn. Ochotona ), † Pseudobellatona , † Ptychoprolagus , † Russellagus , † Sinolagomys and † Titanomys . The earliest one

1274-710: The amount of food they can stockpile for winter months. Pikas prefer foraging in temperatures below 25 °C (77 °F), so they generally spend their time in shaded regions and out of direct sunlight when temperatures are high. A link has also been found between temperature increases and lost foraging time, where for every increase of 1 °C (1.8 °F) to the ambient temperature in alpine landscapes home to pikas, those pikas lose 3% of their foraging time. Eurasian pikas commonly live in family groups and share duties of gathering food and keeping watch. Some species are territorial. North American pikas ( O. princeps and O. collaris ) are asocial , leading solitary lives outside

1323-605: The baby's weight, vital signs, reflexes, head circumference, muscle tone, and posture to help determine the gestational age. Various factors can influence the duration of gestation, including diseases in pregnancy and adequate prenatal care. The rates of morbidity and pre-existing diseases that predispose mothers to life-threatening, pregnancy-related complications in the United States are increasing. Inaccessibility of prenatal care may partially explain this ongoing disparity. During gestation in placental mammals there

1372-419: The breeding season. Pikas have distinct calls , which vary in duration. The call can be short and quick, a little longer and more drawn out or long songs. The short calls are an example of geographic variation. The pikas determine the appropriate time to make short calls by listening for cues for sound localization. The calls are used for individual recognition, predator warning signals, territory defense, or as

1421-492: The case of humans, complex language . Mammals can organize themselves into fission–fusion societies , harems , and hierarchies —but can also be solitary and territorial . Most mammals are polygynous , but some can be monogamous or polyandrous . Domestication of many types of mammals by humans played a major role in the Neolithic Revolution , and resulted in farming replacing hunting and gathering as

1470-812: The clade originating with the last common ancestor of Sinoconodon and living mammals. The earliest-known synapsid satisfying Kemp's definitions is Tikitherium , dated 225 Ma , so the appearance of mammals in this broader sense can be given this Late Triassic date. However, this animal may have actually evolved during the Neogene. As of the early 21st century, molecular studies based on DNA analysis have suggested new relationships among mammal families. Most of these findings have been independently validated by retrotransposon presence/absence data . Classification systems based on molecular studies reveal three major groups or lineages of placental mammals— Afrotheria , Xenarthra and Boreoeutheria —which diverged in

1519-444: The closest thing to an official classification of mammals, despite its known issues. Most mammals, including the six most species-rich orders , belong to the placental group. The three largest orders in numbers of species are Rodentia : mice , rats , porcupines , beavers , capybaras , and other gnawing mammals; Chiroptera : bats; and Eulipotyphla : shrews , moles , and solenodons . The next three biggest orders, depending on

Pika - Misplaced Pages Continue

1568-401: The daytime. They show their peak activity just before the winter season. Pikas do not hibernate and remain active throughout the winter by traveling in tunnels under rocks and snow and eating dried plants that they have stored. Rock-dwelling pikas exhibit two methods of foraging: the first involves direct consumption of food, and the second is characterized by the gathering of plants to store in

1617-1318: The divergence times between these three placental groups range from 105 to 120 million years ago, depending on the type of DNA used (such as nuclear or mitochondrial ) and varying interpretations of paleogeographic data. Monotremata Marsupialia Xenarthra Afrotheria Glires Euarchonta [REDACTED] Eulipotyphla Chiroptera Pholidota Carnivora [REDACTED] Perissodactyla [REDACTED] Artiodactyla [REDACTED] Monotremata [REDACTED] Paucituberculata [REDACTED] Didelphimorphia [REDACTED] Microbiotheria Notoryctemorphia [REDACTED] Peramelemorphia [REDACTED] Dasyuromorphia [REDACTED] Diprotodontia [REDACTED] Cingulata [REDACTED] Pilosa [REDACTED] Hyracoidea [REDACTED] Sirenia [REDACTED] Proboscidea [REDACTED] Tubulidentata [REDACTED] Macroscelidea [REDACTED] Afrosoricida [REDACTED] Eulipotyphla [REDACTED] Chiroptera [REDACTED] Pholidota [REDACTED] Carnivora [REDACTED] Perissodactyla [REDACTED] Artiodactyla [REDACTED] Scandentia [REDACTED] Lagomorpha [REDACTED] Gestation The time interval of

1666-585: The earlier Triassic , despite the fact that Triassic fossils in the Haramiyida have been referred to the Mammalia since the mid-19th century. If Mammalia is considered as the crown group, its origin can be roughly dated as the first known appearance of animals more closely related to some extant mammals than to others. Ambondro is more closely related to monotremes than to therian mammals while Amphilestes and Amphitherium are more closely related to

1715-451: The end of the 20th century. However, since 1945, a large amount of new and more detailed information has gradually been found: The paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself, partly through the new concept of cladistics . Though fieldwork and lab work progressively outdated Simpson's classification, it remains

1764-668: The larger Amniota clade. Early synapsids are referred to as " pelycosaurs ." The more advanced therapsids became dominant during the Guadalupian . Mammals originated from cynodonts , an advanced group of therapsids, during the Late Triassic to Early Jurassic . Mammals achieved their modern diversity in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs , and have been

1813-531: The late Oligocene to middle Miocene. They thrived in Eurasia, North America, and even Africa. The peak of their diversity occurred during the period from the early Miocene to middle Miocene. Most of them became extinct during the transition from the Miocene to Pliocene, which was accompanied by an increase in diversity of the leporids . It has been proposed that this switch between ochotonids and larger leporids

1862-898: The long, cold winter. The pika is also known as the whistling hare because of its high-pitched alarm call it gives when alarmed. The two species found in North America are the American pika , found primarily in the mountains of the western United States and far southwestern Canada, and the collared pika of northern British Columbia , the Yukon , western Northwest Territories and Alaska . Pikas are native to cold climates in Asia and North America . Most species live on rocky mountainsides, where numerous crevices are available for their shelter, although some pikas also construct crude burrows. A few burrowing species are native to open steppe land. In

1911-420: The mother in these lizards which is called viviparous matrotrophy. Ovoviviparous animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. It is similar to viviparity in that the embryo develops within the mother's body. Unlike the embryos of viviparous species, ovoviviparous embryos are nourished by the egg yolk rather than by the mother's body. However,

1960-416: The mother's body does provide gas exchange . The young of ovoviviparous amphibians are sometimes born as larvae , and undergo metamorphosis outside the body of the mother. The fish family Syngnathidae has the unique characteristic whereby females lay their eggs in a brood pouch on the male's chest, and the male incubates the eggs. Fertilization may take place in the pouch or before implantation in

2009-406: The mother's last period. Biochemically, pregnancy starts when a woman's human chorionic gonadotropin (hCG) levels rise above 25 mIU/mL. Biologically, pregnancy starts at implantation of the fertilized egg. Human pregnancy can be divided into three trimesters, each approximately three months long: the first, second, and third trimester. The first trimester is from the last menstrual period through

Pika - Misplaced Pages Continue

2058-476: The mountains of Eurasia , pikas often share their burrows with snowfinches , which build their nests there. Changing temperatures have forced some pika populations to restrict their ranges to even higher elevations. Pikas are small mammals, with short limbs and rounded ears. They are about 15 to 23 cm (5.9 to 9.1 in) in body length and weigh between 120 and 350 g (4.2 and 12.3 oz), depending on species. These animals are herbivores and feed on

2107-1073: The number of adhesion lines on the periosteal bone on the lower jaw. The lifespan does not differ between the sexes. The 34 species currently recognized are: Many fossil forms of Ochotona are described in the literature, from the Miocene epoch to the early Holocene ( extinct species) and present (16.4-0 Ma ). They lived in Europe, Asia, and North America.Some species listed below are common for Eurasia and North America ( O. gromovi , O. tologoica , O. zazhigini , and probably O. whartoni ). Paleontologists have also described multiple forms of pika not referred to specific species ( Ochotona indet.) or not certainly identified ( O. cf. antiqua , O. cf. cansus , O. cf. daurica , O. cf. eximia , O. cf. gromovi , O. cf. intermedia , O. cf. koslowi , O. cf. lagrelii , O. cf. nihewanica ). The statuses of Ochotona ( Proochotona ) kirgisica and O. spelaeus are uncertain. The " pusilla " group of pikas

2156-716: The primary source of food for humans. This led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, and ultimately the development of the first civilizations . Domesticated mammals provided, and continue to provide, power for transport and agriculture, as well as food ( meat and dairy products ), fur , and leather . Mammals are also hunted and raced for sport, kept as pets and working animals of various types, and are used as model organisms in science. Mammals have been depicted in art since Paleolithic times, and appear in literature, film, mythology, and religion. Decline in numbers and extinction of many mammals

2205-496: The same ancestor as the steppe pika ( O. pusilla ). The range of Ochotona was larger in the past, with both extinct and extant species inhabiting Western Europe and Eastern North America, areas that are currently free of pikas. Pleistocene fossils of the extant steppe pika O. pusilla currently native to Asia have been found also in many countries of Europe from the United Kingdom to Russia and from Italy to Poland, and

2254-417: The small intestine to utilize the nutrients. Collared pikas have been known to store dead birds in their burrows for food during winter and eat the feces of other animals. As with other lagomorphs, pikas have gnawing incisors and no canines , although they have fewer molars than rabbits. They have a dental formula of: 2.0.3.2 1.0.2.3 = 26. Another similarity that pikas share with other lagomorphs

2303-548: The therians; as fossils of all three genera are dated about 167 million years ago in the Middle Jurassic , this is a reasonable estimate for the appearance of the crown group. T. S. Kemp has provided a more traditional definition: " Synapsids that possess a dentary – squamosal jaw articulation and occlusion between upper and lower molars with a transverse component to the movement" or, equivalently in Kemp's view,

2352-534: Was caused by expansion of C 4 plants (particularly the Poaceae ) related to global cooling in the late Miocene, since extant pikas reveal a strong preference for C 3 plants ( Asteraceae , Rosaceae , and Fabaceae , many of them C 3 ). Replacement of large areas of forests by open grassland first started probably in North America and is called sometimes "nature's green revolution". Mammal A mammal (from Latin mamma  'breast')

2401-463: Was postulated that the rates of DNA damage and senescence may impact the gestation period as well as lifespan. In viviparous animals , the embryo develops inside the body of the mother, as opposed to outside in an egg ( oviparity ). The mother then gives live birth. The less developed form of viviparity is called ovoviviparity , in which the mother carries embryos inside eggs. Most vipers exhibit ovoviviparity. The more developed form of viviparity

#317682