2 There are 4600 species of mammals known and 300 of these are considered endangered, mainly due to habitat destruction. General characteristics: 1. Mammals are endothermic ( mostly homeothermic) 2. Have hair or fur, if the coat of hair is thick, it is called pelage and species with sparse hair usually have very thick skin or a layer of blubber to insulate against temperature extremes.
3 3. Nourish their young with milk secreted by the female’s nipples. 4 3. Nourish their young with milk secreted by the female’s nipples. 4. All mammals are dioecious with internal fertilization. All mammals are heterogametic which means that the sex of the offspring is determined by the male. Most mammalian embryos are are nourished by a placenta. 5. All mammals breathe with lungs. 6. Have a four-chambered heart and a closed circulatory system.
4 7. Most are terrestrial but a few are marine and one Order has developed true flight. 8. Mammals have the mostadvanced nervous system of any group.All mammals have a lower jaw formed of a mandible called the dentary which articulates with the upper jaw called the squamate and an upper palate which allows young to breathe while nursing.10. All mammals have excellent hearingand external ears called pinnae.
5 Living Representative Mammals There are 21 orders of Mammals classified into two subclasses 1. Subclass Prototheria (egg-laying mammals) ex. Duck-billed Platypus, echidna ( one order) 2. Subclass Theria-( Placental mammals) a. infraclass Metatheria-marsupials (one order) ex. Kangaroo b. infraclass Eutheria- true placental mammals ( 19 orders)
6 MAJOR ADAPTATIONS OF MAMMALS Internal temperature regulation is the most important adaptation in mammals!A. Most mammals are bothendothermic and homeothermic.B. Internal body heat results from camel is example of non homeothermic animalcellular metabolism.1. a typical resting mammal has a metabolic rate 10 X higher than a reptile2. Mammals eat more calories and process them more efficiently than reptiles in order to maintain a higher body heat.3. the smaller the mammal, the greater its body size to surface ratio and the more it must eat to maintain lifeex. A 3 g. mouse eats 5X more than a 10Kg. Dog and 30X more than a 50,000 Kg. elephant.*per gram of body weight
7 MAJOR ADAPTATIONS OF MAMMALS con’t II. Sources of heating the body of a mammal A. Shivering B. brown fat C. changing the pelage with the seasons D. Arrector pilli muscles to erect hairs and trap warm air. E. Insulating blubber accounts for 45% of body weight of seals and whales III. Sources of cooling the body in mammals. A. Panting B. sweating C. remaining inactive during the hottest part of the day D. spreading out and exposing skin where hair is IV. Additional forms of temperature adaptation A. hibernation- winter dormancy B. aestivation-summer dormancy sparse
8 MAJOR ADAPTATIONS OF MAMMALS con’t V. Mammalian integument ( outer covering of skin) 1. hair is formed of fine scales of the protein keratin. a. Various types of mammalian hairs include: soft undercoats, guard hairs, bristles and quills. Hair of sheep and humans grow continuously, also the manes and tails of horses, most other mammal hair growth is determinate. b. Molts are periodic sheds of hair in most mammals. Fox and seals shed once a year in summer, most mammals shed twice a year, in spring and fall. Some mammals change color with the seasons, the white winter coat of Artic mammals is called leukenism. c. Whiskers or Vibrissae are sensory hairs, they provide a tactile extra sense.
9 MAJOR ADAPTATIONS OF MAMMALS con’t V. Mammalian integument 2. glands- sweat, scent, sebaceous, mammary a. Eccrine sweat glands secrete a watery fluid that draws heat away from the body surface…found in hairless regions of the body b. Apocrine sweat glands are larger and open into a hair follicle. They are unrelated to heat and tied to reproductive cycles. In humans, they develop during puberty and are restricted to armpits, ear canals, and pubic areas. c. Scent glands used to communicate with members of same species for breeding, territory marking, and defense d. Sebaceous glands which serve as a dressing to keep skin moist, fur glossy or waterproof. e. Mammary glands occur on all female mammals. Some mammals develop only during nursing, humans develop at puberty with additional fat deposits.
11 MAJOR ADAPTATIONS OF MAMMALS con’t V.Mammalian integument 3. Horns and antlers a. true horns-found in ruminants (sheep and cattle family) 1. hollow sheaths of keratin over bone 2. they embrace a core of bone arising from the skull 3. they are not normally shed and are not usually branched. 4. are found on both sexes within a species but are usually longer in males
13 3. Horns and antlers continued b. Antlers-found in the deer family 1. composed of solid bone when mature 2. grow under a covering of vascular skin called velvet. 3. when growth is complete, the blood vessels constrict and the stag removes the velvey by rubbing it against trees. 4. antlers are shed after breeding season 5. each year the antlers are bigger than the year before 6. only Caribou females have antlers 7. in Moose and Elk, males must acquire over 50 lbs. of calcium each year to grow their antlers
15 Rhino horn C. Rhinocerous Horn 1. hairlike keratinized filaments are cementedtogether2. Are not attached to the skull
16 VI. FOOD AND FEEDINGTeeth-structure of teeth reveal the lifestyle of an animal1. Incisors have sharp edges for biting2. Canines are specialized for piercing3. PreMolars have compressed crowns for shearing4. Molars have larger, flatter tops for Grinding5. Generally, mammals have one deciduous set andone Permanent set.
17 Feeding Specializations 1. Insectivores include shrews, moles, and most bats2. Herbivores include 3 sub-groupsa. Gnawers include rodents, rabbitsb. Browers and grazers include horses, deer, cattle, sheep-all hooved animals are called Ungulates, one sub group of ungulates are called ruminants which have a huge 3-4 chambered stomach. The chambers of the stomach are called the rumen, the reticulum, the omasum, and the abomasum3. Omnivores include raccoons, bears, pigs, rats and most primates4. Carnivores include members of the dog, cat, and seal family.
19 VII. Special Senses in mammals Many mammals have large moveable pinnae(ear flaps) to aid in capturing sound and locatingthe source.B. Senses of smell, sight, and hearing are more or less intense in each species.C. Echolocation is the ability to use sound waves to locate and identify objects.Two orders, Cetacea and Chiropterahave this ability, but it is used in very different environments.
20 Reproduction in Mammals Monotremes are egg-layersand there is a cloaca for fertilization inthe female and the male’s testes arehoused inside the abdominal cavityB. Marsupials have a primitiveplacenta that doesn’t allowfor many nutrients to passfrom mother to offspring, sothe embryo is expelled and crawlsto the marsupium which is a pouchwith a teat inside that the younganimal attaches and completes development.B
21 C. Marsupial males have testes housed outside the abdominal cavity in a sac-like extension called the scrotum. Most placental males also have a scrotum, except for the aquatic mammals and elephants. D. Placental mammals carry their Young in the uterus for the entire fetal period and The fetus is fed and cared for by the placenta.
22 E. Mammary glands are made up of clusters of milk-secreting glands E. Mammary glands are made up of clusters of milk-secreting glands. Milk is made up of the sugar lactose. Various proteins, fats, salts, vitamins and antibodies from the mother’s immune system. Immediately after birth, there is a special milk produced called Colostrum which is made up of large amounts of white cells and antibodies to protect the infant from infection until its own immune system develops.
23 Reproduction TimingA. Estrus is the condition of a female mammal being receptive to the male during certain intervals in an ovarian hormonal cycle.Polyestrus mammals mate and rear young several times a yearex. Mice and RatsMonoestrus mammals mate only once a year (or longer) sometimes called seasonal breedersex. Buffalo and DeerGestation periods-Cats-56 days mice-16 days guinea pigs-77 daysDogs-63 days bats-154 days humans-280 daysElephant-670 days
24 ORDERS OF CLASS MAMMALIA Subclass PrototheriaMonotremata-egg laying mammals with a cloacaDuck-billed platypusLack teeth, but have a beak like a birdFemale platypuses lack nipples but secrete milk onto their fur.Stream dwellers who live on invertebratesSpiny anteaters (echidna)Eat ants and termites and earthwormsFemale lays one egg at a time which she carries in a pouchInfant anteaters live in the pouch for two months sucking milk from two skin projections (primitive nipples)
25 MonotremataSpiny anteater or EchidnaDuck-billed platypus
26 Infraclass Metatheria-one order Marsupialia II. Subclass Theria-two subgroups called Metatheria and EutheriaInfraclass Metatheria-one order Marsupialia1. identified by the presence of a marsupium which acts as a brood pouchfor the developing embryo after it has left the womb.2. only one marsupial species in North America, the opposumspecies of Marsupials, found mainly in Australia, and Central and So. America4. Australia has been marsupial heaven because of its remote localea. the dominate herbivore is the Kangaroob. the dominate carnivores were the TasmanianWolf and the Tasmanian Tiger and the Tasmanian Devilc. other Distinctive Australian marsupials include theWombat, Bandicoot, Koala, and Wallaby
28 B. Infraclass Eutheria True placental mammals made up of 18 orders Order Insectivoraa. small, terrestrial or semi-aquatic mammalswith long tapered snouts, tiny eyes and short fur.b. most are carnivorous, feeding on insects andearthworms.c. some have poisonous salivaEX. Hedgehogs, shrews, moles
30 2. Order ChiropteraAbout 1000 species of bats (second largest order) a. most new-world bats are insectivores and most old-world bats are fruit and flower eaters. b. there are also bird, fish, frog and bat eating bats. Three species of new-world bats are blood-drinkers c. Bats are the only mammals to have evolved true flight. The fore-limbs are modified with the 2nd to 5th digit elongated to support thin membraneous wings, thumb usually free. d. Bats are mainly nocturnal in order to avoid direct competiton with birds for food. e. Bats that are carnivorous have developed Echolocation to locate prey.
32 Order Primates 175 species (including humans) Found in Africa, S.E. Asia, and South AmericaMost species are aboreal or tree-dwellersExamples include: Lemurs, Baboons, Apes, Monkeys, and Chimps & HumansAll have forward facing eyes and opposable thumbsFamily Hominidae includes four genera: Gorilla, Pan (chimps), Pongo (orangutan) and Homo (humans)
34 Order CarnivoraAbout 240 species A. terrestrial carnivores include the dog, cat, weasel, hyenas, racoon, bear, badger, coyotes B. aquatic carnivores include seals, otters, walrus C. not all carnivores are truly carnivores, bears and racoons are omnivores and the Panda eats only bamboo. D. Most other carnivores have a well developed sense of smell, and have limbs adapted for running down prey.
35 Order Carnivora Bear family Weasel family Dog family Musk family Marine familyCat family
36 Order Perrisodactyla Order Artiodactyla Odd-toed animals (ex. Horses, rhinos, and tapirs)AndOrder ArtiodactylaEven-toed animals (ex. Swine, camel, deer, giraffes, cattle, sheep, and hippos)Collectively called the UngulatesAll are hooved herbivoresHave limbs adapted for running in order to escape predators.One sub group of Ungulates are called ruminants, these animals hae a modified digestive system to aid in digesting Cellulose. ( This group includes cattle, sheep, and antelope)“ Eyes on the side, likes to hideEyes in the front, likes to hunt!”
39 Order Sirena ( ex. Manatees, dugongs) Order hyracoidea ( ex. Hyraxes) 7. Order Proboscidea (ex. Elephants)Order Sirena ( ex. Manatees, dugongs)Order hyracoidea ( ex. Hyraxes)These three orders are referred to as theSubungulatesBecause they have a caecum and some have vestigial hoovesAll are herbivoresThought to have come from a common ancestor in Africa.
40 Order ProboscideaIndian elephantAfrican elephant
42 Order Hyracoidea “Shrew” Hyraxes-closest living relative to the elephant
43 (ex. Anteaters, sloths, armadillos) 7. Order Xenartha(ex. Anteaters, sloths, armadillos)Only found in the new world tropicsHave extra cervical joint and lack canine teeth and incisorsAnteaters lack all teeth but have a long, sticky tongue that they capture ants withSloths are herbivores that sleep a lot and spend their life hanging upside down. Their body temperature is very low.Armadillos are omnivores and have distinctive bony plates covering their bodies.
45 (Whales, dolphins and porpoises) 8. Order Cetacea(Whales, dolphins and porpoises)Highly intelligentForm social groupsAll excellent swimmersTail fins undulate up and down rather than side to side as fish doNostrils are located on top of the head and is called a “blow hole”This order is divided into two suborders, the Mysticeti which filter feed on small invertebrates and the Odontoceti which use Echolocation to locate prey in the ocean
47 (Ex. Beavers, rats and mice, squirrels) 9. Order Rodentia(Ex. Beavers, rats and mice, squirrels)Largest order with 1760 speciesHave one pair of elongated incisors that grow throughout lifeMost rodents are herbivores but some, such as rats are omnivoresHave the highest rate of reproduction and many are considered pestsbottom of the food chain!
49 10. Order Lagomorpha (ex. Rabbits, hares and pikas) Also have continuosly growing incisors but also have a second pair of incisors in the upper jaw.Are similar morphologically but different physiologicallyHares have well-developed young, that find their own homes in the grass and the mother visits them to nurse several times a day. Usually have three to four offspringex. Jackrabbits, snowshoe haresRabbits have hairless and blind young in a burrow and have 6-9 offspring at a time.ex. Cottontails-easter bunnies