Information Of Mammals Foreword

No one knows exactly how many distinct organisms inhabit our planet, but more than 5 million different species of animals and plants could exist, ranging from microscopic algae and bacteria to gigantic elephants, redwood trees and blue whales. Yet, throughout this wonderful tapestry of living creatures, there runs a single thread Deoxyribonucleic acid or DNA. The existence of DNA, an elegant, twisted organic molecule that is the building block of all life, is perhaps...

Three ecological postulates that underlie conservation biology

Modern conservation biologists must often transcend the traditional boundaries of academic disciplines, for these scientists increasingly need to know about politics, economics, philosophy, anthropology, and sociology in order maintain or restore the health of ecosystems. However, because conservation biology is fundamentally concerned with the dynamics of wildlife populations, a solid understanding of biology and ecology is paramount for workers within the discipline. Three ecological...

Behavior

Australian mammals are almost all nocturnal or crepuscular and the carnivorous marsupials are no exception. Most are nocturnally active, although some diurnal foraging and basking activity has been recorded in a number of species for which detailed field observations are available, including in antech-inuses and thylacines. In some populations, spotted-tailed quolls exploit opportunities to prey upon nocturnal possum prey asleep in tree hollows, and are almost arhythmic in their activity. Three...

Captive breeding and reintroduction

In recent years ex situ conservation efforts have become increasingly important. Zoos, botanical gardens, wildlife parks, and conservation trusts now work in collaboration to maintain captive assurance colonies of threatened plants and animals. Studbooks on target species are kept by participating institutions, and breedings are scheduled in consultation with conservation geneticists. The proximate mission of ex situ colonies is to maximize genetic diversity within a captive population of...

Reproduction in marsupials

In marsupials, ova are shed by both ovaries into a double-horned or bicornate uterus. The developing embryos remain in the uterus for 12-28 days, and most of the nourishment comes from an energy sac attached to the egg (yolk sac). There is no placenta (except for one groups of marsupials, the bandicoots, that have an interchange surface that resembles a true placenta). Gestation is thus short (less than one month), and much of the development of the young will occur outside of the female...

Reproductive biology

One of the most remarkable montreme features, and the one that initially seemed to be the biggest obstacle to their inclusion in the class Mammalia, is the fact that females lay eggs instead of giving birth to live young. The eggs are subsequently brooded and hatched outside the mother's body, as in reptiles and birds. Monotremes typically breed slowly. It takes a mother platypus about six months to raise a small litter of one or two young to independence, seven months in the case of the...

Physical characteristics

Dasyuromorphians are quadrupedal (move on four legs), with four toes on the front feet, four or five toes (including The Tasmanian devil (Sarcophilus laniarius) has teeth capable of crushing bone. (Photo by Erwin & Peggy Bauer. Bruce Coleman, Inc. Reproduced by permission.) The Tasmanian devil (Sarcophilus laniarius) has teeth capable of crushing bone. (Photo by Erwin & Peggy Bauer. Bruce Coleman, Inc. Reproduced by permission.) a clawless toe called a hallux) on the hind feet, long tails...

Feeding ecology and diet

The platypus is a predator, mainly feeding on bottom-dwelling aquatic insects such as caddis-fly and mayfly larvae. The platypus is also partial to worms, snails, freshwater shrimps and crayfish, and pea-shell mussels. The size of its prey is limited by the fact that platypus teeth are lost quite early in development and replaced by flat, molar-like grinding pads at the back of the mouth. Unlike most mammalian teeth, these pads grow constantly to compensate for surface wear. A platypus may find...

Significance to humans

Apart from an occasional food source, the smaller species of daysurids seem not to have had great significance for aboriginal peoples. The larger, more distinctive species like quolls, were frequently totemic species and had dreaming histories and individual names that persisted long after they became extinct in a region. 1. Long-tailed planigale Planigale ingrami) 2. Long-tailed dunnart Sminthopsis longicaudata) S. Brush-tailed phascogale Phascogale tapoatafa) 4. Pilbara ningaui Ningaui...

How to get through

The most significant challenge is a mechanical one soil is a dense, more or less hard and compact medium that cannot be penetrated easily. Movement through soil is energetically very costly. Vleck (1979) has estimated that a 5.3-oz (150-g) pocket gopher burrowing 3.3 ft (1 m) may expend 300-3,400 times more energy than moving the same distance on the surface. To keep the energy costs of burrowing at the minimum, the tunnel should have a diameter as small as possible. To achieve this,...

Cardiovascular and respiratory adaptations

Like birds, bats have hearts that are about three times bigger than those of comparably sized mammals. The heart muscle fibers (or cells) in bats possess higher concentrations of ATP (the molecule that is utilized for energy by cells) than observed in any other mammal. These adaptations enables bats to pump more blood during a flight, a period of peak demand for oxygen. Resting bats may have heart rates as low as 20 beats per minute. Within minutes of initiating flight, the heart rate may rise...

Sperm and egg formation

Sperm cells are made in the testes of males. Through a process of cellular division called meiosis, sperm-producing cells with regular genetic material (diploid cells, meaning they posses two copies of each chromosome) undergo division with the end product being two cells each with only one copy of each chromosome (haploid, half of the parent cell). Because sperm production is optimal at temperatures slightly colder than average body temperature, testes are housed in a pouch These giraffes...

Challenges

Because water is so dense (up to 800 times denser than air), it can easily support an animal's body, eliminating the need for weight-bearing skeletons like terrestrial animals. Water is also more viscous than air, and this coupled with the high density has resulted in aquatic animals adapting a very streamlined shape, particularly the carnivores. This makes them very fast and powerful swimmers, enabling them to catch their prey. Many of the adaptations of aquatic organisms have to do with...

Conservation

The pattern of endangerment among the carnivorous marsupials is consistent with that for Australian mammals in gen- The fat-tailed pseudantechinus (Pseudantechinus macdonnellensis) is a carnivorous marsupial. (Photo by B. G. Thomson Photo Researchers, Inc. Reproduced by permission.) The fat-tailed pseudantechinus (Pseudantechinus macdonnellensis) is a carnivorous marsupial. (Photo by B. G. Thomson Photo Researchers, Inc. Reproduced by permission.) eral. Australia accounts for 50 of the world's...

Longtailed planigale

Planigale ingrami (Thomas, 1906), Alexandria, Northern Territory, Australia. Length 2.2-2.6 in (55-65 mm). Smallest of the planigales and the smallest marsupial with very flat head and thin tail longer than head and body. Seasonally flooded grasslands and savanna woodlands. Forages and rests in crevices in moist, contracting (cracking) soils, under rocks, and in tussocks. Planigales may have evolved the very flat head to occupy the niche of foraging in seasonally flooded cracking soils....

How to tell time

Light-dark rhythm (photoperiod) is known to regulate production of the hormone melatonin that, in turn, regulates circadian (meaning around a day, as in a 24-hour period) rhythms by a feedback mechanism. In surface-dwelling vertebrates (including human), melatonin is produced during dark hours. It can therefore be expected that subterranean mammals living in constant darkness would display high melatonin levels. This does seem to be the case, yet the role of melatonin in regulating activity...

Nutrition and the reproductive cycle

Energy requirements and food intake of pregnant females are about 17-32 higher than non-reproducing females, and yet only 10-20 of this additional energy is retained as new tissue by the developing uterus. The rest of the energy is lost as heat, slowing down the growth rate and thus lengthening the gestation period. A slower fetal growth rate may be advantageous in an environment with limited dietary protein or minerals, especially in the case of such animals as the fruit-eating or leaf-eating...

Gestation and neonate type

Period Gestation

With only a few exceptions, each mammal species has a characteristic gestation period that shows remarkably little variation. In comparisons between species, gestation periods tend to increase as body size increases. However, effective comparisons of gestation periods among mammals must take into account a fundamental distinction in the state of the neonate at birth. As a general rule, it is possible to distinguish fairly clearly between mammals that give birth to several poorly developed...

Alstons woolly mouse opossum

Allen, 1900 , Cartago, Costa Rica. OTHER COMMON NAMES French Souris-opossum laineuse d'Alston Spanish Zorrici. PHYSICAL CHARACTERISTICS Length 6.7-7.9 in 17-20 cm weight 2-5.3 oz 60-150 g . One of the largest mouse opossums. The dorsal hair is yellowish brown to reddish underparts are paler. Distinct black mask over each eye. The tail is long, slender, and naked. There is no marsupium. The feet have strongly opposable thumbs. Caribbean coast of Central America from...

Humans the most successful invasive species

The magnitude of the invasive species problem in agricultural and natural ecosystems prompted U. S. President Bill Clinton to organize the heads of eight federal agencies into the National Invasive Species Council in 1999. Actually, humans rank among the most successful invasive mammal species. Humans are believed to have spread from Africa to Europe and Asia over 100,000 years ago, and reached the island continent of Australia between 40,000 and 60,000 years ago. But humans are apparently...

Milk and lactation

At birth, the young no longer can rely on the direct exchange of nutrients through the placenta or in monotremes, through nutrient stored in the egg . Thus, nutrition of young requires an additional process, and milk is the nutrient that serves that purpose. Milk is unique to mammals, and all species of mammals are capable of producing milk. Milk production occurs in the mammary glands, which resemble sweat glands in form but become mature only following parturition or birth of young. The milk...

Nearctic

This region comprises North America up to northern Mexico and Greenland. Ten orders are present, including 37 families, and around 643 species. Two families are endemic, each containing a single species. These are the Antilocapri-dae pronghorn and the Aplodontidae sewellel, or mountain beaver , endemic to western North America. There are a large number of endemic rodents. These include the woodrats genus Neotoma , 17 species of ground squirrel Citettus , three antelope squirrels, 16 chipmunks,...

Peculiar processes Delayed fertilization and delayed implantation

Barred Bandicoot Nest

The opportunity to find a suitable mate is essential for reproduction, but because gestation is fixed in duration, timing of mating has direct implications on the timing of parturition. However, mammals have evolved two strategies to separate A western barred bandicoot Perameles bougainville joey suckling in mother's pouch. Photo by Jiri Lochman Lochman Transparencies. Reproduced by permission. A western barred bandicoot Perameles bougainville joey suckling in mother's pouch. Photo by Jiri...

Reproductive system

There are three different modes of reproduction used by mammals. The monotremes, whose extant members are the echidnas and duck-billed platypuses, lay eggs. The therians marsupial and placental mammals give birth to live young. Marsupial newborns are undeveloped some mammalogists call them embryos . After only a short gestation period they must make their way to a teat outside the mother's body a teat that may be in a pouch in species that have pouches to finish development. The embryos of...

Social systems

Sexual reproduction in animals generally puts a heavier load on the female side. In mammals, however, this bias in cost of reproduction is far more extensive due to the period of gravidity pregnancy and the subsequent lactational period, both of which cannot be taken over by a male. Consider a female mouse suckling six young shortly before weaning, each young has about half her weight. Thus, she has to nourish and support 400 of her body weight There is an even higher evolutionary pressure on...

How to find a partner

In order to reproduce, mammals have to find and recognize an appropriate mate belonging to the same species, opposite sex, adult, in breeding mood, sexually appealing . Monogamous mammals undergo this search once in life solitary mammals have to seek mates each year. Subterranean mammals do not differ in this respect from their surface-dwelling counterparts. In 1987, two research teams reported, simultaneously and independently, the discovery of a new, previously unconsidered, mode of...

Camels and llamas

The camel was and is an excellent transport vehicle in desert areas where horses and donkeys cannot survive. In deserts, camels can survive ten times longer than humans and four times longer than donkeys. They provide meat, milk, blood, leather, and hair, and excrements are used as fuel. The wild Bactrian camel Camelus ferus is the ancestor of the Bac-trian or two-humped camel C. ferus f. bactrianus . It comes from east and central Asia. The remaining populations live in the periphery of the...

Body design

To understand bat body adaptations for flight, it may be instructive to examine bird bodies. Bird bodies are designed for mass reduction. They do this in a number of ways. They have lost teeth and the accompanying heavy jaws and jaw musculature over evolutionary time. They have thin, hollow, and strong bones. Many bones are fused or reduced in size. The long bony tail of their ancestors has been greatly reduced to the small vestigial pygostyle. Birds have a series of air sacs in the body that...

Sexual dimorphism

Male and female mammals obviously differ in various features that are directly linked to reproduction, as is the case with the sex organs of both sexes and the mammary glands of females primary sexual characteristics . However, males and females can also differ in a variety of features that are not directly associated with reproduction secondary sexual characteristics . Such secondary differences between males and females, like the human facial beard, are collectively labeled sexual dimorphism....

Migration

Caribou Migration

Migrations are mass movements from an unfavorable to a favorable locality and in plains-dwelling, large herbivores such as reindeer, bison, zebras, wildebeest, or elk they can be quite spectacular. In large sea mammals migrations are no less important, but to us are merely less visible and it has taken much effort by science to document at least a part of their extent, leaving much that is still shrouded in mystery. Mass-migrations occur when individuals flood to distant birthing or breeding...

Delayed fertilization

Sperm storage occurs in bats inhabiting northern temperate regions such as the little brown bat Myotis lucifugus , and also in many bats such as noctule Nyctalus noctula . In the little brown bat, the testes become scrotal in the spring, and most sperm production is completed by September. The sperm are then stored until copulation commences months later. Females are inseminated in the fall and winter, while they are in hibernation. Sperm are then stored again, this time in the female...

The Hagenbeck concept

Carl Hagenbeck was an animal entrepreneur. He supplied animals to zoos and was also an animal trainer. He pioneered many display and exhibit techniques. Hagenbeck initially gained his reputation by exhibiting people and animals in traveling exhibits. On October 6, 1878 over 62,000 people visited the Berlin Zoo to see his traveling exhibit of Nubians from the Sudan, Laplanders, Eskimos, Kalmucks, Tierra del Fuego natives, and Buddhist priests. There were also elephants, camels, giraffes, and...

Oriental region

The Oriental region includes Asia south of the Himalayas, southern China, the Philippines, and Southeast Asia up to Wallace's Line, between the islands of Bali and Lombok. The region has two endemic orders, Scandentia tree shrews , with 19 species, and Dermoptera colugos . There are two species of colugos, often also called flying lemurs, a doubly confusing name as they are not lemurs and they glide, rather than fly. There are 50 families in the region, four endemic, and 260 genera, about 35 of...

Disadvantages of domestication

The number of domestic animals greatly exceed the number of wild or related species. In some cases, their wild ancestors have been completely exterminated. The breeding of domestic animals has provided people with many indisputable advantages, but it has its downside. The grazing of large livestock herds diminishes food and water resources of local wild Domesticated cats have helped people keep homes free of rodents for many thousands of years. Photo by Ernest A. James. Bruce Coleman, Inc....

Sexual selection and the evolution of species and their attributes

The pressures caused by females choosing males will lead to two types of evolutionary selection inter-sexual selection adaptations to win members of the other sex , and intrasexual selection adaptations to win access to mates over members of the same sex . Both vary in importance according to species and environments. Inter-sexual selection leads to the development of adaptations, morphological, physiological, or behavioral, to seduce Top Placental mammal development. Middle row Marsupial...

Domestic horse Equus caballus f caballus

Image Farmer Plowing With Draft Horse

The horse was the last of the five most common livestock animals to be domesticated. After a short period when it was used only as a source of meat, it became established as a perfect means of transport until the recent past. The history of the wild horse in Europe and Asia from the end of the Pleistocene until its domestication in perhaps 4000 to 3000 B.C. is poorly understood. According to prevailing opinion, wild horses during the domestication belonged to two species. These were the...

Bali cattle Bos javanicus f domestica

Bali cattle is the domestic form of wild banteng B. javanicus , which lives in the forests of Java, Borneo, Malaysia, and Thailand today. Its domestication took place in Java around 1000 B.C. Wild bantengs were caught and tamed in the Middle Ages, in Bali, Sumatra, and Java until the eighteenth century. Bali cattle are smaller than banteng, the horns lack the characteristic curvature, and the skull is smaller. The external sexual signs are weaker than in the wild species. The domestic species...

Density estimate

Density estimates have two components, and both cause difficulties to biologists the amount of area surveyed and the number of animals. As opposed to an index, the density estimate relies on a measure of area surveyed and not on effort. If the survey area is a true island, then the measurement is straightforward. If the survey area has an arbitrary boundary between inside and outside, assumptions have to be made as to how the animals move with respect to the boundary. If the area surveyed is a...

Horns and antlers

Horns and antlers are found in the order Artiodactyla cattle, sheep, deer, giraffes, and their relatives . Several other types of mammals have similar head structures, but true horns, originating from the frontal bone of the skull and found only among the Bovidae cattle, antelopes, buffalo , consist of a bony core enclosed by a tough keratinized epidermal covering or sheath. True horns are not branched, although they may be curved. Horns grow throughout the life of the animal and are used for...

Gayal Bos gaurus f frontalis

The gayal or mithan is the domesticated form of the wild gaur B. gaurus . For a long time, it was not clear if the gayal and gaur were the same separated species or if the gayal had developed by crossbreeding of a gaur with bantengs or zebu. The gayal is noticeably smaller than the gaur, it has shorter conical horns, a markedly shorter skull, and a wider and flatter forehead. It has a large double dewlap on the chin and neck. It is most commonly brown and black but can also be spotted or white....

Adaptations in the digestive system

Digestive System Mammal

All carnivores, when fed a whole prey-based diet, consume proteins and fats from the muscle, vitamins from organs and gut contents, minerals from bones, and roughage from the hide, feathers, hooves, teeth, and gut contents. Felids are set apart from other, more omnivorous meat eaters because of their inability to effectively utilize carbohydrates as an energy source. They therefore depend on a higher concentration of fats and protein in their diet, as well as dietary sources of preformed...

Record keeping

Animal record keeping is the foundation of captive animal management. Zoo professionals depend on detailed direction from animal records. Mammals with missing or unknown ancestry or other life history information are of very limited use in long term management strategies. The International Species Information System ISIS , first developed in 1973, collects animal data from over 560 institutions in 72 countries on 6 continents and stores them in a computerized database. These data are kept by a...

Mammals IV

Abercrombie, PhD Wofford College Spartanburg, South Carolina Cleber J. R. Alho, PhD Departamento de Ecologia retired Universidade de Bras lia Bras lia, Brazil Universidad de la Rep blica Oriental Anders Angerbj rn, PhD Department of Zoology Stockholm University Stockholm, Sweden William Arthur Atkins Atkins Research and Consulting Normal, Illinois Paul J. J. Bates, PhD Harrison Institute Sevenoaks, Kent United Kingdom Amy-Jane Beer, PhD Origin Natural Science York, United Kingdom...

Bat wing morphology and its role in powered flight

Chief among the many adaptations of the bat for powered flight is the bat wing, and the flapping flight style that uses muscle power to generate lift and thrust. The bat wing evolved from the forelimbs of a terrestrial mammalian ancestor. The mammalian forelimb is exceedingly mobile because the shoulder joint between the scapula shoulder bone and the humerus upper forelimb bone is loosely held together with muscles. This allows for actual rotation of the arm around the shoulder joint in many...

The physics of powered flight

Glaucomys Volans

Once a means for detecting and avoiding obstacles was developed in a bat ancestor, the lineage was free to expand into the nocturnal flier niche. Powered flight allows access to flying insects. Because gliders do not have the maneuverability to pursue flying insects, this feeding niche was wide open during early bat evolution. The difference between powered flight and other modes of traveling through the air is maneuverability. Gliders such as the colugo have extra skin at the body's sides,...

What is rumination

The act of rumination, or chewing the cud, is the regurgitation and remastication of undigested fibrous material before it is swallowed again. As the food reenters the rumen, it undergoes further fermentation. The products of fermentation in the form of broken-down food particles then slowly pass to the other parts of the stomach, where the usual digestive juices of the abomasum perform their work. Ruminants secrete copious amounts of saliva that serve to buffer fermentation products in the...

The diversity of mammalian social systems

Mammals Reproductive System

Before approaching explanatory questions by means of Tin-bergen's questions again, a brief attempt at categorization of social systems in order to categorize the diversity of mammalian social systems, there are several variables that need to be described for each species. One is the degree of sociality. We find at least three types of social organization here first are the solitary individuals that do not regularly have any social contact with conspecifics outside the narrow timespan of...

Body design and skeletal system

Mammal Reptile Ear

As endotherms, mammals require more energy than ec-tothermic animals. Consequently, many mammal traits evolved to conserve energy. This is particularly true of the mammal skeleton. Mammals differ as a group from other living quadrupedal vertebrates in that their limbs are positioned directly below the body, allowing more energy-efficient locomotion. The lateral placement of the limbs on reptiles and amphibians requires them to spend considerable energy keeping their bodies lifted off of the...

Reproductive processes

Mammal Reproduction

The primary reproductive process in female mammals is the production of eggs ova from follicles in the ovary. In a non-pregnant female mammal, production of eggs is typically a cyclical process, although there are varying degrees of seasonal restriction such that some female mammals do not show repeated cycles. Seasonality of reproduction in mammals is mainly governed by annual variation in rainfall and vegetation, and hence becomes increasingly common at high latitudes. In many mammals,...

Sociality in the framework of Tinbergens questions

What do we know about phylogeny It is not normally possible to find behavior in fossilized form, thus we have to take another, but also reliable approach, by comparing the phenomenon in question among as many living species as possible. When doing this with regard to social systems, the most basic one seems to be a sort of solitary or dispersed female system, foraging alone in undefended home ranges. This pat tern can be found in members of so many different taxa that we may assume it to be one...

A zoologist answers A highly derived amniote

Black Handed Spider Monkey

Many of the characters common to mammals do not appear in other animals. Some of them, of course, can be observed also in birds a very high in respect to both maximum and mean values metabolic rate and activity level or complexity of particular adaptations such as advanced parental care and social life, increased sensory capacities, and new pathways of processing sensory information or enormous ecological versatility. Fine differences between birds and mammals suggest that the respective...

Role of sensory data

Stephen Dalton

Mammals sense or gather information about their environment and use it to make decisions that affect their survival and reproduction. Sometimes, species initially respond to one type of cue. For example, female hammer-headed bats Hypsig-nathus monstrosus in Africa locate groups of males by listening to their distinctive calls. Picking a male to mate with, however, is a decision females appear to make only after visiting several in the line of displaying suitors. A female's actual choice may...

The dietary needs of mammals

Like the rest of the animal kingdom, mammals need food for energy and the maintenance of bodily processes such as growth and reproduction. The chemical compounds used to supply the energy and building materials are obtained by eating plants or organic material. Both plant- and animal-based sources of food are made up of highly complex compounds that need to be digested and broken down into simpler forms. Four of the most common naturally occurring elements oxygen, carbon, hydrogen, and nitrogen...

Nervous system and sensory organs

Convolutions The Neo Cortex

Mammals have relatively larger brains than other vertebrates. From monotremes to marsupials to eutherians, the mammal brain increases in size and complexity, primarily by the expansion of the neopallium. The neopallium or neo-cortex is a mantle of gray matter that first appeared as a small region between the olfactory bulb and the larger archipallium. The neopallium in mammals has expanded over the primitive parts of the vertebrate brain, dominating it as the cerebral cortex. The cerebral...

Cardiovascular and respiratory systems

Oxycyznated Red Blood Cells

In order to distribute nutrients and oxygen needed for metabolism, mammals need a highly efficient circulatory system. The main differences in circulatory structure between mammals and most other vertebrates are in the heart and in the red blood cells. The mammalian heart has four chambers as do birds and crocodilian reptiles compared to the three chambers found in the reptiles except the crocodilians . The additional chamber is the result of a muscular wall or septum that divides the ventricle...

Palaearctic region

Skulls Muridae

The Palaearctic region covers Europe, North Africa, most of the Arabian Peninsula, and Asia north of the Himalayas, including Japan and Korea. The Palaearctic is the largest of the major faunal regions in terms of its geographical area and it contains a wide range of habitats. Despite this, it has the lowest rate of endemism of all the major faunal regions. Thirteen orders and 42 families are present, none of them endemic. About 30 of the 262 genera and 60 of the 843 species that occur are...

Digestive system

Ardvark Pictures

To fuel endothermy, mammals require more calories per ounce or gram of tissue than do ectothermic vertebrates such as reptiles. This is accomplished by more efficient digestion of food stuffs and more efficient absorption of nutrients. This efficiency begins with specialization of the teeth. Mammals have four different kinds of teeth heterodonty that are ideally shaped to cut, slice, grind, and crush food. An exception is the toothed whales in which all the teeth are similar homodonty . The...

The most diversified animals

There are about 4,600 species of mammals. This is a relatively small number compared to the 9,600 species of birds or 35,000 fish species and almost nothing in comparison to about 100,000 species of mollusks or some 10,000,000 species of crustaceans and insects. Even such groups as extant reptiles with 6,000 species and frogs with about 5,200 species are more diversified at the species level. Nevertheless, in diversity of body sizes, locomotory types, habitat adaptations, or feeding strategies,...

Horse 43 mph 70 kmh

Kangaroo Locomotion

The horse has a stiffer spine, making it better suited for endurance. B. The cheetah is the fastest land mammal flexibility in its spine allows for longer strides. C. The kangaroo has more upward movement with each leap, and does not move forward as quickly as the horse or cheetah. Illustration by Patricia Ferrer A. The horse has a stiffer spine, making it better suited for endurance. B. The cheetah is the fastest land mammal flexibility in its spine allows for longer strides. C. The...

Seasonal changes in nutritional requirements

Groundwater Seasonal Changes

Changes in diet often follow the changes in seasons. When researchers at Sea World, Durban, traced the annual food consumption of their female dusky dolphin Lagenorhynchus obscurus over a 13-year period, they found that her annual food intake jumped from 4,784 lb 2,170 kg when she was five years old, to nearly 6,393 lb 2,900 kg the year after. This increase coincided with the installation of a cooling system that was used in the summer in the years thereafter, and after her sixth year, her food...

Suckling as a defining feature

Patterns of reproduction are truly fundamental to mammal biology. This is at once apparent from the word mammal itself. In all species of the class Mammalia monotremes, marsupials, and placentals , females suckle their offspring, and almost all of them have teats mammae to deliver the products gathered from the milk-generating glands. As defining features of the class Mammalia, mammary glands and milk production lactation are clearly central to mammalian evolution. Indeed, these features...

A paleontologist answers The product of the earliest divergence of amniotes and index fossils of the Cenozoic

Mammals are the only extant descendants of the synap-sids the first well-established group of amniotes, named after a rounded temporal opening behind the orbit bordered by the jugale and squamosum bones. Since the beginning of amniotes, evolution of synapsids proceeded separately from the other amniotes, which later diversified in particular reptile lineages including dinosaurs and birds. The first amniotes recorded from the middle Carboniferous 320 million years ago were just synapsids and...

Evolution of aquatic animals

Sea Otters Their Habitat

Marine fossils paint an idyllic scene of aquatic animal life in its infancy some 670 million years ago mya soft coral fronds arch from the ocean floor, jellyfishes undulate in the currents, and marine worms plow through the ooze. But a geologically brief 100 million years later, at the dawn of the Cambrian period, the picture suddenly changes. Animals abruptly appear cloaked in scales and spines, tubes and shells. Seemingly out of nowhere, and in bewildering abundance and variety, the animal...

Types of populations to manage

Frankham 1986 documents four types of captive populations of interest to zoos. They are summarized in the following groups The goal for these species is to selectively breed for traits adapted to captivity in an effort to establish a tractable, easily managed population. This could include animals that are docile and do not stress easily. ENDANGERED SPECIES IN CAPTIVITY FOR LONG TERM CONSERVATION The goal for these species is long-term maintenance of a viable population and the preservation of...

Neotropical region

Neotropical Region Species

The Neotropics includes South America, Central America from southern Mexico southwards, and the West Indies. This region contains a very diverse fauna. Twelve orders are represented, two of them endemic. The Paucituberculata, shrew opossums, consists of three genera and five species, all found in the Andean region. The Microbiotheria has a single species, the monito del monte Dromiciops australis , distributed in southern South America. The order Xenarthra sloths, armadillos and anteaters is...

The media

Cetacean Taste Receptors

Most of the 5,000 or so living species of mammals have eyes and, in many, the keenness of their vision visual acuity is at least equivalent to that of humans. A few mammals have very limited vision, such as river dolphins Platanistidae, Lipotidae, Pontoporiidae, and Iniidae that live in extremely murky water or moles Talpidae that live in total darkness indeed, in some moles, the optic nerve has actually degenerated. In mammals' eyes, a lens focuses light on the retina, a layer of...

Ecology

Desert Mouse Burrow

Ecology, the study of an organism's relationship to its surroundings, consists of several distinct areas, all of which have their own specific approaches and methods. Ecophysiology deals with physiological mechanisms, evolutionary ecology is concerned with life history-related, fitness-relevant, and population-genetic aspects, behavioral ecology looks at how the animal deals with its surroundings, and community ecology asks how groups of species can live together. This text will approach how...

A child answers A hairy fourlegged animal with a face

Snout Fossorial Animals

Against expectation, the three characteristics reported by this naive description express almost everything that is most essential about mammals. Hair, or fur, probably the most obvious mammalian feature, is a structure unique to that group, and unlike the feathers of birds is not related to the dermal scales of reptiles. A mammal has several types of hairs that comprise the pelage. Specialized hairs, called vibrissae, mostly concentrated in the facial region of the head, perform a tactile...

Copulation and fertilization

Copulation

Once eggs are released from the female ovaries, they migrate down into the uterus. Eggs are not self-propelled, and migration occurs passively by gliding over cells that have minuscule sweepers cilia . In contrast, sperm cells each have a long flagellum that provides mobility. But for sperm to reach the egg or eggs, copulation must first occur. Copulation in most terrestrial species occurs as the male straddles the female from behind. Typical examples of this type of copulation occur in deer,...

Peculiar mechanisms Induced ovulation

Induced ovulation occurs when release of eggs in females is triggered by a stimulus, most often physical such as copulation, but also behavioral or pheromonal such as the vicinity of males. In contrast to spontaneous ovulators, or species where the release of eggs depends on the seasonal photope- African lioness Panthera leo with her cubs. Photo by Joe McDonald. Bruce Coleman, Inc. Reproduced by permission. African lioness Panthera leo with her cubs. Photo by Joe McDonald. Bruce Coleman, Inc....

Australian region

Endemic Species Oriental Region

This region includes Australia, New Zealand, New Guinea, Sulawesi, and some islands in the southwest Pacific. The Australian fauna is the least diverse in terms of the number of orders and species present, but certainly the most distinctive of all the major regions. Excluding Cetacea, only eight orders of mammals are native to Australia, but five of these, Monotremata and four orders of marsupials, are endemic. The other three indigenous orders are Chiroptera, Rodentia, and Carnivora. The...

Reproductive tract

Mammalian Female Reproductive Tract

Two key features in the initial development of the mammalian reproductive tract are crucial for understanding its evolution in both males and females. First, the system begins development as essentially separate left and right halves that are virtually mirror images of one another bilateral symmetry . Second, there is a very close connection between the development of the reproductive tract and that of the kidneys and allied structures renal system . According to species, these initial...

Changes in the skeleton and internal organs

Striking changes occurred in the skull for example, there was a shortening of the snout and jaws and at the same time a reduction of the number of teeth dog, cat, cattle, pig . The shortened snout and accentuated rounded eyes induced the juvenile appearance of the eternal cub. It also resulted in lower brainpower and smaller brain volume. The skeleton became less resistant than that of wild animals as a consequence of the comfortable life with its lack of movement. For the same reasons, the...

Locomotor adaptations

Evolution Mammary Gland Development

The musculoskeletal design of the mammalian body has accomodated many diverse means of locomotion, not only in terrestrial environments but also in aquatic and aerial niches. Many mammal species are capable of using several different means of locomotion, but much of the body configuration is determined by the dominant mode of locomotion used by a particular species. Mammal tail diversity reflects different functions. 1. A jerboa's tail is used as a counterweight and balance 2. A spider monkey's...

Milk composition

Picture And Information Mammals

According to Elsie Widdowson in 1984, of the 4,300 species of mammals, only the milks of 176 have been analyzed for protein, fat, and carbohydrate. Of these analyses, she said, only the figures for 48 of those species are considered to be reliable. The difficulty in the analyses lies with the fact that milk composition changes rather markedly during a lactation cycle. The first milk, or colostrum, contains a high concentration of maternal antibodies, or immunoglobins, active phago-cytic cells,...

Reconstruction of phylogenetic trees

Phylogenetic Tree Red Panda

Regardless of whether morphological or molecular data are analyzed, reconstruction of phylogenetic relationships between species depends on interpretation of shared similarities. In principle, it is relatively easy to survey similarities between species for individual characters. This task is particularly straightforward with molecular data because the individual components at defined positions in sequences of DNA nucleotide bases or proteins amino acids are relatively simple and directly...

Integumentary form and function

Teeth Herbivore Carnivore Adaptation

The integumentary system is composed of the skin and its accessory organs. The mammalian integument has many of the characteristics that we consider mammalian. Generally mammalian skin is thicker than the skin of other vertebrates because of its function in retarding heat and water loss. The integument consists of two major regions, the epidermis and dermis. Squamous cells are produced by a basal or germina-tive layer on the border of the epidermis and dermis. As cells are produced at the basal...

Claws nails and hooves

Gas Exchange Lions

The distal ends of mammal digits possess keratinized sheaths or plates that are epidermal derivatives forming claws, nails, or hooves. Only the members of the whale and sirenia seacows families lack these structures. Claws are usually sharp, curved, and pointed. In many cases mammal claws are very similar to the claws found in other vertebrates. A claw consists of a dorsal plate called the unguis and a ventral plate called the subunguis. The unguis is curved both in length and width and...