Mammals are characterized by warm-bloodedness, hair or fur, highly developed brains, muscular diaphragms, mammary glands, and parental care. They have four-chambered hearts, skulls with teeth and jaws, and two sets of teeth. Mammals have four limbs adapted for locomotion like walking, running, swimming, flying or burrowing. They maintain a constant body temperature through homeothermy. Their skin has hair and glands. Mammals are classified into monotremes, marsupials, and placental mammals.

1. Mammals

2. Mammals are vertebrate animals
constituting the class Mammalia, and
characterized by
• Warm blooded (Homeothermy)
• Have fur and Hair on the body
• Highly developed brain
• Muscular diaphragm
• Have mammary gland
• A higher degree of parental care

3. They have
• Four chambered heart with double
circulation.
• Skull with teeth and powerful jaws

4. Mammalian teeth are Heterodont
• 2 set of natural teeth(Deciduous teeth and permanent teeth)
• Four types of teeth are adapted for different types of function
during feeding

5. Limbs and Locomotion
• Have four limbs(one pair of fore and one pair of hind limbs)
• These are pentadactyl having five digits in each limb(Used
locomotion and support the body weight)

6. •Limbs adapted for mainly
walking and running(In some
groups adapted for swimming,
flying and burrowing)

7. Hind limbs are
absent in cetaceans
and sireneans

8. Homeothermy
• It is the process by which the animal more or
less maintains a constant body temperature
irrespective of the fluctuations in
environmental temperature.
• It is confined to only Birds and Mammals
• They usually have a core body temperature of
around 37 C over a wide range of
environmental temperatures.

9. • Metabolic rates of homeo-therms are greater than those of poikilo-therms.
• Therefore homeo-thermic animals require more food than poikilothermic (Cold
blooded) animals.

10. Mammalian skin
• It is made up of a thick epidermis and an underlying dermis
• Epidermis is multicellular and the outer layers are made up of dead cornified cells
forming a layer called stratum corneum.
• The innermost layer is actively dividing and is called stratum germinativum
• The mammalian skin is quite different in structure and function from the skin of
reptiles.

11. • Hairy skin reduces the conduction
of body heat and in many mammals
it is colored in different patterns for
camouflage.
• Skin derivatives such as claws,
hooves, nails, horns and antlers are
present

12. • Reptilian skin is completely dry and protective in function
• Mammalian skin is equipped with varying amounts of hair which serve as a
protective layer and several skin glands perform secretory function

13. Classification
• The class Mammalia which is represented by 4600 living species is
usually divided into three subclasses :
• Prototheria/ egg laying mammals
• Metatheria/marsupial mammals
and
• Eutheria/Placental mammals

14. Subclass : Prototheria (Egg laying mammals)
• Order : Monotremata
Duckbilled platypus Echidnas

15. Subclass : Metatheria (Pouched mammals)
• Order : Marsupilia
Kangaroos
Opossums
Koalas

16. Subclass Eutheria (Placental mammals)
• This group includes a bulk of placental mammalian species usually divided into
18 orders.
• Some examples would be Moles ,shrews and hedgehogs, Bats, Cats, Dogs,,
Wolves, Fox, Lemurs etc

17. Monotremes : Major characters
• Monotremes originated more than 130 million years ago and only three species survive
today.
• Restricted to Australia
• This is a primitive mammalian group and all of the species lay shelled eggs
• In addition to the mammalian features they exhibit some features which are unique for
them too
• Hence they are described as reptile like mammals

18. • Reptilian characters
• Lack of external ear (Pinnae)
• Presence of cloaca through which the digestive tract and urinogenital ducts
open to then exterior. This is the common outlet for faeces urine and eggs
(The name monotreme means one opening)
• Lay large eggs with abundant yolk and hard shell

19. •Mammalian characters in monotremes
• presence of hair
• four chambered heart
• Presence of diaphragm
• Presence of three middle ear ossicles
• Presence of mammary glands

20. • Unique features to monotremes
• The adults have a horny beak with teeth being found only in
young stage
• Mammary glands without nipples
• Males have hollow spurs on their hind legs with which they
can inject poisonous venom during aggressive encounters
with other males

21. Duck billed platypus
• This is an aquatic form found in streams of Australia making nests or holes in the
banks for nesting
• Body is covered with a dense dark wooly fur
• The head is prolonged into a bill
• There are no teeth in the adult
• Bill is used for stirring up the mud to cacth living worms and molluscs
• Limbs are short but prominent hand and feet with webs and claws
• Males have spurs

22. Spiny ant eater/ Echidnas
• Two types – short nosed echidna (Tachyglossus) of Australia and long nosed
echidna (Zaglossus) of New guinea.
• Terrestrial and burrowing animals
• Spines are modified hair which resemble those of porcupines.
• Jaws form a long horny snout or rostrum and for feeding they have a long
extensible sticky tongue.
• Short-nosed echidna feeds on ants and termites while the long nosed echidna feds
mainly on earthworms.

23. • They do not have a tail
• They are nocturnal animals
• Females lay egg and keep them in temporary ventral pouch which developes only
in breeding season.
• Young hatch out in temporary pouch and suck milk from mother, then they
develop in the pouch until spines develop and then develop in burrows

24. Marsupials
• This include pouched mammals such as kangaroos and opossums.
• Females develop ventral pouch called marsupium.
• Marsupials show many similarities with placental mammals
• Live in the Australian region and in south and central America.

25. • After birth the young crawl to the pouch and they are nursed by the mother.
• Nipple swells in the young one’s mouth so that the premature baby cannot drop
off while the mother is moving.
• There are over 260 species of marsupials.

26. Eutherian (Placental Mammals)
General characters
• They posses
A placenta
Anal and urogenital apertures with separate openings
Young which are born in advanced stage of development
Testes that descend into scrotum and lying behind the penis

28. Primitive placentals (Order : Insectivora)
• This order includes the most primitive mammals
• It includes animals like shrews, moles and hedgehogs.
• These are nocturnal insect eating animals
• Shrews are nocturnal, insect and fruit eating and squirrel like with a tail

29. Moles are highly specialized
for underground life, with
powerful limbs and broad
claws for digging, external
ears are reduced, tiny eyes
practically useless

30. • Hedgehogs live among bushes and feed on insects.
• Mainly nocturnal and sleep by the day.
• Armed with hard erectile spines over the body and often curl up when threatened.

31. Flying mammals (Order : chiroptera)
• This includes bats
• They are the only mammals with true flight and this feature is responsible for their
worldwide distribution
• Bats are entirely nocturnal by habit and practically blind by the day.
• Eyes are specially adapted for night vision,
• Sense of touch and hearing are remarkably developed.

32. Adaptations
• Modified fore limbs of the bat make up the wing, It is made up of double layer
of skin extending partly on to the hind limb as well,
• First digit is free of the wing and bears a claw.

33. • Unlike in birds the hind limbs of bats is unable to support their entire body weight.
• It is usually short and rotated upwards
• Bats often use the limbs to hang upside down to rest
• While on ground they crawl using the claws of the forelimbs

34. • Many bats are entirely dependent on the echolocation for avoiding obstacles,
to navigate and to catch prey.
• These emit high pitched sound from larynx well beyond the hearing range of
humans.
• They are able to detect and evaluate the reflected sound wavs and thereby
navigate easily and catch prey
• They have complex nose leaves developed around th nasal region which acts
like a megaphone, directing ultrasound
• Many bats also have relatively large ears to collect the echoes

35. Rodents (Order : Rodentia)
• Rodents include squirrels, rats and mice, porcupines and guinea pigs.
• They are gnawing animals
• Rodents are the most successful of all living mammals
• There are over 3000 species
• They are found to occur all over a wide range of habitats
• Majority are terrestrial, no pure aquatic forms but beavers are adapted for fresh
water habitats.
• Others such as squirrels are arboreal

36. • Typically herbivores but most members are secondarily adapted for an
omnivorous diet as well.
• Most characteristic feature is the paired incisors in each jaw.
• These are very large pair of teeth and their gnawing power against each other
gives them sharp edges.

37. Edentates (Order : Edentata)
• Edentates includes three groups of mammals which are the anteaters, tree sloths
and armadillos.
• Teeth are completely absent in the anteaters and in sloths and armadillos, the front
teeth are never present but the hind teeth are present.
• The feet have claws are well developed for digging and hanging.

38. • Ant eaters have elongated snout.
• Sloths are arboreal animals which spend much of their time hanging upside down
from branches.

39. • Armadillos are the only living mammals with a bony armour.
• These are omnivores terrestrial and fossorial forms.
• Feed on worms , grubs, vegetables and bird eggs.
• They role up into a ball when threatened covering their body with the bony arour

40. Carnivorous mammals : Order Carnivora
• These are the competitive and strongest of animals.
• They are of large size and predatory habits
• Well developed for flesh eating with several adaption
• such as sharp claws
• Powerful jaws
• Strong projecting canines
• All these area adaptations to capture and kill prey

41. Cetaceans (Order : Cetacea)
• This is an order of marine mammals that is highly specialized for a completely
aquatic life style.
• The body has secondarily taken on streamlined fish like form
• This order includes whales and dolphins
• These are the most highly modified mammals completely adapted for aquatic
lifestyle

42. • To reduce friction skin doesn’t have hair and insulation is provided by a
subcutaneous layer of fat called as blubber
• Being descended from land mammals, the cetaceans are also air breathers
• They come up to the surface periodically to get fresh air.
• Forelimbs are modified into flippers
• Hind limbs have disappeared
• Dorsal fins developed as stabilizers
• Tail is dorso-ventrally flattened and ends up in two horizontal flaps

43. • Tail moves up and down while swimming.
• Eyes are very small and ears lack pinna but have a minute opening.
• One or two nasal openings are present called blow holes on top of the head
• Most are carnivorous and found all over the world.

44. • This order includes two major groups of whales , the whale-bone whales and
toothed whales
• Whale bone whales are filter feeders and includes the blue whale
• Toothed whales are carnivores and include dolphins, porpoises , sperm whales
and bottle nosed whales.
Blue whale Toothed whale

45. • Many cetaceans also use echolocation to navigate and communicate with each
other.

46. Placental herbivores
• Herbivores are plant eaters
• They have some adaptations to enable them to digest plant matter more effectively
• Specialized premolars and molars(cheek teeth) enable them to grind plant matter
• Incisors sharp for cutting and cropping
• Specially designed legs to enable them to run fast to escape predators with
features such as long limbs the presence of horny cover known as hoofs

47. • Herbivores maintain a symbiotic
relationship with microorganisms that
inhabit their digestive tract.
• Stomach of herbivores/ruminants are
greatly modified than that of other
mammals.
• Stomach is divided into four
fermentation chambers(rumen,
reticulum, omassum and abomasum)
• This enables them to properly chew the
food eaten once again by regurgitating
within their mouth and later
swallowing the processed food.

48. • Food first enters the rumen once the animal
feeds on the vegetations, there it is mixed
with mucus and acted on by micro
organisms residing within the rumen.
• These organisms breakdown cellulose by
producing the enzyme cellulase thus
enabling herbivores to tap into the energy
locked in cellulose which if not wouldn’t
be accessible
• Then this food is regurgitated into the
mouth , chewed well and swallowed back
where it goes into reticulum and omassum,
where it is mechanically churned
• Then the food enters abomasum or true
stomach where it undergoes digestion by
digestive juices secreted within.

49. Diversity
• Some important groups are
• Hoofed mammals : Cattle (Artiodactyla) and horse(perissodactyla)
• elephants (Proboscidea)
• Dugongs (Sirenia) and
• Rabbits (lagomorpha)

51. • The elephants are the large mammals forming the family Elephantidae in the order
Proboscidea.
• Three species are currently recognised: the African bush elephant (Loxodonta africana), the
African forest elephant (L. cyclotis), and the Asian elephant (Elephas maximus).
• Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia.
Elephantidae is the only surviving family of the order Proboscidea;

53. Primates : General characters
• A primate is a mammalian
animal constituting the
taxonomic order Primates.
• Primates arose 55–85 million
years ago from small
terrestrial mammals
(Primatomorpha), who
adapted to living in the trees
of tropical forests

55. • Primates are divided into two distinct suborders
• The first is the strepsirrhines (meaning wet-nosed) - lemurs, galagos, and lorisids.

56. • The second is haplorhines - the "dry-nosed" primates - tarsiers, monkeys, and
apes, the latter including humans.

57. General characters of primates
• Primates have forward-facing eyes on
the front of the skull; binocular
vision allows accurate distance
perception
• The primate skull has a large, domed
cranium, which is particularly
prominent in anthropoids.
• The cranium protects the large brain, a
distinguishing characteristic of this
group

58. • Primates generally have five digits on each limb
(pentadactyly), with keratin nails on the end of each
finger and toe.
• The bottom sides of the hands and feet have sensitive
pads on the fingertips.
• Most have opposable thumbs, a characteristic primate
feature most developed in humans,

59. • Thumbs allow some species to use tools.
• In primates, the combination of opposing thumbs, short fingernails (rather than
claws) and long, inward-closing fingers is a relict of the ancestral practice of
gripping branches,
• and has, in part, allowed some species to develop brachiation (swinging by the
arms from tree limb to tree limb) as a significant means of locomotion.

60. brachiation (swinging by the arms
from tree limb to tree limb)

61. • Primates show an evolutionary trend
towards a reduced snout.
• The evolution of color vision in primates
is unique among most eutherian
mammals.
• Sexual dimorphism is often exhibited to
a greater degree in Old World species
(apes and some monkeys) than New
World species.
• Primates usually have dimorphism in
body mass and canine tooth size along
with pelage and skin color.
• The dimorphism can be attributed to and
affected by different factors, including
mating system, size, habitat and diet.

63. • Primate species move by brachiation, bipedalism, leaping, arboreal and terrestrial
quadrupedalism, climbing, knuckle-walking or by a combination of these
methods.