Mammals

04/12/2023

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By: Vivek Shukla & Ritesh GuptaSub Teacher : Mrs. Sachi Sachan

04/12/2023By : Vivek Shukla and Ritesh 2

Seminar on Phylum

Vertebrata

By : Vivek Shukla and Ritesh 04/12/2023

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CLASS 6. MAMMALIA

Subphylum 2. Gnathostomata

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Classification of Vertebrata


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Salient Feature


7General Characters

They are warm blooded and most evolved animals of Animal Kingdom.

Skin is provided with Hairs, Sweat glands & Sebaceous glands.The forelimbs and hind limbs are variously adapted for walking,

running, climbing, burrowing, swimming or flying. Wings are absent (except in bats).The teeth are present within the socket of jaws (thecodont

dentition) & are differentiated into incisors, canines, premolars and molars (heterodont).

They have bone marrow.


Respiration is through lungs only.The heart is four - chambered with two auricles and two

ventricles,They are viviparous forms of life, i.e., the young ones

are born directly (except platypus & echidna) (& some give birth to very poorly developed young ones like kangaroo).

A muscular diaphragm is present that separates thoracic cavity from the abdominal cavity.

The females are provided with milk producing mammary glands that secrete milk for the nourishment of the young. In males, they become vestigeal.

Body is divisible into head, neck, trunk and tail.


The red blood corpuscles are non- nucleated biconcave (except in camel).

External ear (pinnae) present. Middle ear with three ossicles (malleus, incus and stapes).

The developing embryo gets the nutrition and oxygen through the placenta.

Excrete urea (ureotelic animals).They live in all kind of habitats from equator to poles.

They are primarily terrestrial animals.


Urinary bladder – need more water per day.Advanced kidneys – filter more blood.


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Phylogeny• Separated into three groups

• Prototheria (before gestation) – egg laying mammals

• Metatheria (middle gestation) – pouched mammals

• Eutheria (true gestation) – live birth from uterus

Phylogeny – Evolutionary history of organismsGestation – the time period between fertillisation and parturition (delivery ).


18Milk

Produced in mammary glandsMay have been sweat glandsFeed young, increase success

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Types of teeth

Incisors – cuttingCanines – can be enlarged, piercingCarnassal – shearing, remove meat from

bonesMolars - grinding

By : Vivek Shukla and Ritesh

20Cardiovascular System

Body temperature is internally regulated (endothermic)

Heart is 4-chamberedHigh metabolism Heart rate – depends on size of animal (smaller = faster rate)


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Reproductive System

Dioecious (unisexual)Highly variable in shape.Placental mammals.Nonplacental mammals.


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Reproductive System

Most mammals are viviparous, giving birth to live young. However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian mammal.


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Digestive System

Length differs based on diet Predators short Herbivores very long Omnivores medium length


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Skeletal systemThe majority of mammals have seven cervical

vertebrae (bones in the neck), including bats, giraffes, whales, and humans. The exceptions are the manatee and the two-toed sloth, which have only six cervical vertebrae, and the three-toed sloth with nine cervical vertebrae.


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Nervous System

All mammalian brains possess a neocortex, a brain region unique to mammals. Placental mammals have a corpus callosum, unlike monotremes and marsupials. The size and number of cortical areas (Brodmann's areas) is least in monotremes (about 8-10) and most in placentals (up to 50).


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FeedingTo maintain a high constant body temperature is energy

expensive – mammals therefore need a nutritious and plentiful diet. While the earliest mammals were probably predators, different species have since adapted to meet their dietary requirements in a variety of ways. Some eat other animals – this is a carnivorous diet (and includes insectivorous diets). Other mammals, called herbivores, eat plants. A herbivorous diet includes subtypes such as fruit-eating and grass-eating. An omnivore eats both prey and plants. Carnivorous mammals have a simple digestive tract, because the proteins, lipids, and minerals found in meat require little in the way of specialized digestion. Plants, on the other hand, contain complex carbohydrates, such as cellulose.


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The digestive tract of an herbivore is therefore host to bacteria that ferment these substances, and make them available for digestion. The bacteria are either housed in the multichambered stomach or in a large cecum. The size of an animal is also a factor in determining diet type. Since small mammals have a high ratio of heat-losing surface area to heat-generating volume, they tend to have high energy requirements and a high metabolic rate.


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Mammals that weigh less than about 18 oz (500 g) are mostly insectivorous because they cannot tolerate the slow, complex digestive process of a herbivore. Larger animals, on the other hand, generate more heat and less of this heat is lost. They can therefore tolerate either a slower collection process (those that prey on larger vertebrates) or a slower digestive process (herbivores). Furthermore, mammals that weigh more than 18 oz (500 g) usually cannot collect enough insects during their waking hours to sustain themselves. The only large insectivorous mammals are those that feed on huge colonies of insects (ants or termites).


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Some examples are :

1 & 2

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APES TO HUMAN1 & 2

Evolution


Thank You

Mammals

Education

Transcript of Mammals