We the : We the Advanced Homeotherms Dr Subroto Biswas We the
Mammals
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The study of mammals is known as : The study of mammals is known as Mammology
Let us see what characters are Unique to mammals ? : Let us see what characters are Unique to mammals ? Skin with hair
Mammary glands
Seven cervical vertebrae
Breathe with lungs
Highly evolved tetrapods
Parental care
When did they originate ? : When did they originate ? In Jurassic period
About 180 million years ago
From mammal-like reptiles, the therapsids (extinct cotylosaurian reptiles). This presentation is brought to you by ….. Bisbio.in
Slide 6 : Coenozoic era
Regarded as the age of mammals. This presentation is brought to you by ….. Bisbio.in
Slide 7 : Mammalia …….4000 species
Spread over …. 127 living orders.
Features of mammals : Features of mammals Warm blooded homeothermic (36°C or 98°F)
In some mammals the homeothermy is imperfect. In which one ? monotremes
Slide 9 : The body …. head, neck, trunk and tail.
Body covered with hair … epidermal in origin.
But which mammal Sparsely distributed hair on body ? In aquatic mammals (whales)
Mammals : Mammals The skin of is thick and water–proof
Provided with sweat, sebaceous, scent and mammary glands.
Sweat glands (sudorific glands ) are epidermal in origin but found in the dermis.
They regulate the body temperature and also act as excretory organs.
Slide 11 : Sebaceous glands secrete an oily substance called sebum (for soft smooth skin)
The sebaceous glands in the pectoral region are modified into mammary glands except in prototherians : The sebaceous glands in the pectoral region are modified into mammary glands except in prototherians This presentation is brought to you by ….. Bisbio.in
Slide 13 : Aquatic mammals have a thick layer of fat in the subcutaneous tissue….. known as Blubber …as thermal barrier
Slide 14 : Mammals are tetrapods (two pairs of pentadactyle limbs)……..adapted for walking, running, climbing, burrowing, swimming and flying This presentation is brought to you by ….. Bisbio.in
Hind limbs are absent in whales and sea cows. Forelimbs are modified into flippers in aquatic mammals. : Hind limbs are absent in whales and sea cows. Forelimbs are modified into flippers in aquatic mammals.
Slide 16 : Nictitating membrane (Plica semilunaris)
is vestigial in mammals
Slide 17 : External ears …auditory pinnae are present.
Absent in aquatic mammals, the prototherians and ant eaters.
Slide 18 : Teeth are firmly fixed in sockets of jaw bones ……. thecodont.
All the teeth differ in shape and function…. heterodont dentition. : All the teeth differ in shape and function…. heterodont dentition.
Slide 20 : Four kinds of teeth
Incisors
Always borne in front of the jaws
Serve for cutting.
Canines
Long and sharp in carnivores
Help in tearing the flesh.
Absent in herbivorous mammals.
Premolars
Grinding teeth with cusps.
Molars (wisdom teeth)
Resemble premolars in their structure and function.
Not represented in milk dentition.
Slide 21 : The skull has a large cranial cavity.
The skull is dicondylic.
Slide 22 : Mammals possess 7 cervical vertebrae
with a few exceptions
Slide 23 : There are 4 pairs of salivary glands
Parotid,
Sublingual,
Sub maxillary and
Infraorbital
How many are there in man ?
3 pairs of salivary glands.
Infraorbitals are absent in man.
Slide 24 : Males possess a muscular, copulatory organ called penis.
Two testes in mammals are situated outside the abdomen in scrotal sacs except in monotremes and whales.
Slide 25 : Mammals are viviparous.
They give birth to young ones (except in prototheria).
The eggs are usually minute and without yolk (except in monotremes).
Hence, they are called alecithal eggs.
The cleavage is holoblalstic.
The clitoris is homologous to the penis of male.
Slide 26 : What is gestation period ? The time taken by the young one to develop inside the uterus of the mother (=intra uterine period).
Slide 27 : Mammals are highly evolved and most intelligent of all animals.
Slide 28 : The body cavity has a unique structure. Name it. Transverse muscular wall called diaphragm
Slide 29 : The anus is separated from urino-genital aperture.
Cloaca is absent in mammals except in monotremes.
Slide 30 : The red blood corpuscles are round, biconcave and enucleated.
Blood has blood platelets.
Slide 31 : The brain is of the most advanced type.
The two cerebral hemispheres are connected by corpus callosum.
Slide 32 : How many pairs of cranial nerves are present in mammals? Twelve pairs
Slide 33 : Mammals are diverse
DIVERSITY OF MAMMALS : DIVERSITY OF MAMMALS Divided into 3 sub classes ….
1. Prototheria
2. Metatheria (maruspialia)
3. Eutheria (placental mammals)
Sub-Class 1 : PROTOTHERIA : Sub-Class 1 : PROTOTHERIA Teatless mammary glands
Males possess functional mammary glands.
PROTOTHERIA : PROTOTHERIA The feeding of young with milk by father and mother (parents) is known as ? Gynaecomastism
Slide 37 : Prototheria includes only one living order monotremata.
It includes three living genera….
Ornithorynchus,
Echidna and
Zaglossus
Slide 38 : Possess a number of reptilian characters in addition to the mammalian characters.
Connecting link between reptiles and mammals. PROTOTHERIA
Ornithorynchus or duckbilled platypus are found in…... ? : Ornithorynchus or duckbilled platypus are found in…... ? Australia and Tasmania
Echidna or Tachyglossus or spiny anteater found in Tasmania and New Guinea. : Echidna or Tachyglossus or spiny anteater found in Tasmania and New Guinea.
Short-beaked Echidna (an Australian monotreme) : Short-beaked Echidna (an Australian monotreme) All mammals have hair and make milk - but not all carry the young inside the body till birth!
Sub Class 2 METATHERIA(or MARSUPIALIA or DIDELPHIA) : Sub Class 2 METATHERIA(or MARSUPIALIA or DIDELPHIA)
Features of Marsupials : Features of Marsupials Marsupials or brood pouch is present in females.
Newborn opossum (Didelphis) : Newborn opossum (Didelphis)
Slide 45 : The young ones are born …….
naked and blind
Possess, clawed forelimbs by which they move into the brood pouch. Marsupials
Slide 46 : Marsupials exhibit discontinuous distribution.
Some marsupials like Kangaroo live in Australia and oppossums live in south America.
Australia is described as the land of marsupials. Marsupials
Baby in marsupium : Baby in marsupium
An albino kangu : An albino kangu
A marsupial : A marsupial Didelphis is an American opposum.
Sugar glider on a tree (marsupial) : Sugar glider on a tree (marsupial)