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Biology 11Phylum ChordataSubphylum VertebrataClass Mammalia: US!

+ Mammalian Evolution

evolved from the reptiles

+Mammalia Objectives

General characteristics

complete body systems: circulatory, respiratory, integumentary, reproductive, nervous, skeletal, excretory, digestive

3 orders and example animals

+Mammalian Characteristics

4 chambered heart

Hair or fur

Diaphragm for breathing

Amniotic egg

Mammary glands for nursing young

Extensive post natal care

Learning and reasoning levels of behavior

+Advances and Characteristics of the body systems:1. Circulatory System

Complete four chamber heart and circulatory pattern

efficient transport system to every cell of the body

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+2. Respiratory System

Highly efficient lungs

Chest muscles and a diaphragm to expand the chest cavity to increase capacity to hold air

+3. Body CoveringCovered with hair for insulation (modified scales) and sensing

All mammals are endothermic (generate heat to maintain their body temperature)

Have a layer of subcutaneous fat for insulation and food storage

+4. Reproductive SystemSexual reproduction

Internal fertilization & development

Amniotic egg: modified to include placenta in some mammals

Nurse young with mammary glands

Young born very immature - require extensive post natal care

+5. Nervous SystemMost developed nervous system in the animal kingdom

Great increase in cerebrum – responsible for thinking and learning

Very well developed senses

Behavior reaches learning and reasoning levels – infant care, mating & societies

+Brain Regions and Functions

Frontal Lobe thinking, planning, & central executive functions; motor execution.

Parietal Lobe somatosensory perception, integration of visual & somatospatial information.

Temporal Lobe language function and auditory perception involved in long term memory and emotion.

Occipital Lobe visual perception and processing.

+Class Mammalia

6. Skeletal SystemLimbs are well adapted for land & allow very rapid movement

Also adaptation of limbs to move in air & water

+7. Excretory Systemhighly developed kidney

– controls composition of body fluids

nitrogenous wastes from blood urea

urine = urea + water + other wastes

allowed mammals to live in many habitats ie. deserts – concentrate urine and feces conserve water

+ 8. Digestive System

highly developed and specialized organs responsible for digestion

Structure dependent on diet

1. Monotremes

Have fur & nurse young

Have a bird bill & lay eggs which they incubate outside body

Today represented only by Duck Billed Platypus and the two species of Anteater

ClassificationThe mammals are placed into three Orders:

+2. The MarsupialsFemales do not have a

uterus

Young are “born” immature and finish their development in a pouch

In pouch, young attach to mammary gland

Examples : Australia: kangaroos,

wallabies, possums and koala bears

+3. The Placental Mammals

Young develop completely inside the mother’s womb due to placenta

The placenta is an organ that allows for gas exchange and nutrient/waste exchange between mother & fetus

Most common order of mammals today - includes us!

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