MAMMALS

VVI Examples of Mammalia for Entrance Exams are:
  • Duckbilled platypus (Ornithorhynchus)
  • Spiny anteater (Echidna)
  • Camel and Llama
  • Kangaroo (Macropus)
  • Didelphis (Opossum)
  • Mole or Talpa
  • Pteropus (Flying fox or Frugivorous bat)
  • Rhinolopus (Insectivorous bat)
  • Desmodus (Vampire or Sanguivorous bat)
  •  Rat (Rattus)
  • Squirrel (Funambulus)
  • Tiger (Panthera tigris)
  • Dog (Canis lupus familiaris)
  • Flying lemurs (Galaeopithecus)
  • Giant anteater (Myrmecophaga)
  • Sloth (Bradypus)
  • Manis or Scaly Anteater (Pangolion)
  • Rabbit (Oryctolagus)
  • Hare (Lepus)
  • Dolphin (Dorphinus)
  • Blue Whale; the largest animal (Balaenoptera musculus)
  • Killer Whale (Orcinus)
  • Horse (Equus equus)
  • Zebra (Equus zebra)
  • Rhino (Rhinocerous)
  • Hippopotamus
  • Camel (Camelus dromedarius)
  • Red deer (Cervus)
  • Water buffalo (Bubalus)
  • Sea cow ( Rhytina) – has 6 cervical vertebrae
  • Manatee (Trichechus)
  • African conies (Hyrax)
  • Cape anteater or Aardavark (Orycteropus)
  • Elephant
  • Gibbon (the smallest man-like ape)
  • Chimpanzee (Pan- the most intelligent ape)
  • Gorilla (largest and most powerful ape)
  • Spider monkey (Ateles)
  • Red monkey (Macaca rhesus)


General Characteristics of Mammals

· Evolved from therapsid reptilian ancestors during the Triassic period and became dominant in the Cenozoic era (Age of mammals).
· Homeothermal (warm-blooded). Body covered by hairs. Hair is formed by the deposition of alpha–keratin.
· Mammary glands (modified sweat glands) are present.
· Skin glandular consisting of sweat glands. Sebaceous glands.
· Skull is dicondylic.
· Ear-Pinna present.
· 12 pairs of ribs and cranial nerves are present.
· Heterodont, thecodont and diphyodont dentition.
· 7 cervical vertebrae present in all.
· RBCs biconcave, non-nucleated (Except in Camel and Llama)
· Respiration by lungs.
· 4 chambered heart. Only a left systemic arch is present.
· Presence of diaphragm.
· Cerebrum is highly developed with two hemispheres connected by the corpus callosum.
· Kidneys metanephric. Ureotelic mode of excretion.
· Testes in males situated in scrotum outside the abdominal cavity (except in Prototherians, aquatic mammals and elephants).
· Viviparous (except prototherians which are oviparous).
· Amniota
· Vertebrae are amphiplatyn or acoelous.
· Teeth are heterodont, thecodont and diphyodont. Eggs are microlecithal and homolecithal or isolecithal.
· Feet are plantigrade (Human), digitigrade (Cat) and unguligrade. (Horse)


Classification of Mammalia

· Mammals are classified into two subclasses.
a. Prototheria
b. Theria

a) Prototheria
· They are primitive and egg-laying mammals and confined to Australia.
· Mammary gland without nipples.
· They are connecting links between reptiles and mammals.
· Body temperature ranges from 25- 280C.
Order – Monotremata

· They have no ear pinnae, uterus or vagina.
· They have cloaca and Abdominal testes .
Examples: Duckbilled platypus (Ornithorhynchus), Spiny anteater (Echidna)


b) Theria
It is divided into two infra-classes.

i. Metatheria
· They are pouched mammals or marsupials so young born in the immature stage and becomes mature in the abdominal pouch.
· In the brain corpus callosum is absent.
· They short gestation period and no allantoic membrane.
Examples: Kangaroo (Macropus) of Australia, Didelphis (Opossum) of North America

ii. Eutheria
· They are viviparous or placental mammals
It is divided into 6 orders
1. Insectivora- smallest and most primitive form. Eg Mole or Talpa

2. Chiroptera- commonly called bats. They have patagia and echolocation.
Examples: Pteropus (flying fox or frugivorous bat), Rhinolopus (insectivorous bat) and Desmodus (Vampire or sanguivorous bat)

3. Rodentia- small gnawing mammal, largest order, no canine teeth but incisors are chisel-like.
Example: Rat (Rattus), Squirrel (Funambulus).

4. Carnivora- Predatory flesh-eating mammals.
Example: Tiger (Panthera tigris), dog (Canis lupus familaris)

5. Dermaptera- Gliding mammals with patagium.
Example: Flying lemurs (Galaeopithecus)

6. Edentata- Teeth are absent or only reduced molars are present without enamel.
Example: Giant anteater (Myrmecophaga), Sloth (Bradypus)

7. Pholidota- Body is covered with large overlapping horny scales, the tongue is long and protrusible, anteater.
Example: Manis or scaly anteater (Pangolin)

8. Lagomorpha- herbivorous, has second pair of upper incisor and no canine teeth, coprophagous and leaping locomotion.
Example: Rabbit (Oryctolagus), Hare (Lepus)

9. Cetacea- aquatic lung-breathing mammals with blubber under skin. No skin glands, ear pinnae, no hind limbs, forelimbs are modified into paddles. No hairs except snout, bone spongy.
Example: Dolphin (Dorphinus), Blue Whale; the largest animal (Balaenoptera musculus), Killer Whale (Orcinus)

10. Perissodactyla- odd-toed hoofed animals, incisor present in both jaw.
Example: Horse (Equus equus), zebra (Equus zebra), Rhino (Rhinocerous)

11. Artiodactyla- even-toed hoofed animals, incisors and canines in upper jaw usually absent. They are ruminants except for the pig.
Example: Hippopotamus, Camel (Camelus dromedarius), Red deer (Cervus), Water buffalo (Bubalus)

12. Sirenia- herbivorous aquatic mammals with paddle-like forelimbs. No hindlimbs and pinnae.
Example: Sea cow ( Rhytina) – has 6 cervical vertebrae; Manatee (Trichechus)

13. Hyracoidea- small guinea pig-like mammals, snout ear and legs short whereas forelimb has 4 toes and hind limb has 3 toes.
Example: African conies (Hyrax)

14. Tubulidenta – has a tubular mouth, the tongue is slender and protrusible, no incisor and canines, burrowing feet. Ant and termite eaters.
Example: Cape anteater or Aardvark (Orycteropus) of South Africa.

15. Proboscidea- nose and upper lip modified into proboscis, pachyderm and largest land animal, presence of tusk.
Example: Elephant (Elephas)

16. Primates- most intelligent and has highly developed brain. The first digit is usually opposable, plantigrade and has binocular vision.
Example: Gibbon (the smallest man-like ape), Chimpanzee (Pan- the most intelligent ape), Gorilla (largest and most powerful ape), Spider monkey (Atele), Red monkey (Macaca rhesus)

Note: Milk glands are functional in both males and females in prototherians.

· Male duck-billed platypus is the only poisonous mammal.
· Prototheria and marsupial have no corpus callosum in brain.
· Marsupials have no allantois placenta.
· The flying organ of the bat is called a patagium.
· Elephants are called pachyderm because they have hairless skin adapted for hot climates.
· Tusk of the elephant is modified upper incisors.
· Sea cow has only six cervical vertebrae.
· Ruminants are called cud-chewing animals.



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