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MAMMALS

DR. U P K EPA

DEPARTMENT OF ZOOLOGY & ENVIRONMENTAL MANAGEMENT

Class Mammalia

• Includes 4000 species
• Most dominant land animals on earth.

Course code : ZOOL 1201

Learning outcomes of this lecture series: At the end of this course, the student will be able to describe the diversity of form and function of mammals and discuss their evolutionary trends

Key Characteristics of Mammals

• All mammals have the following in common:
  • Are endothermic
  • Hair
  • Specialized teeth
  • Females produce milk in mammary glands to nourish live young

Mammals and Hair

• Mammals are the only animals that have hair

Endothermy

• Mammals are endothermic (warm-blooded)
  • Are animals that can maintain a constant body temperature despite the changes in the environment
• Endothermy allows animals to live in cold environments

Endothermy

• The respiratory and circulatory systems of mammals are adapted to endothermy
• They acquire and distribute oxygen more efficiently than the respiratory and circulatory systems of ectoderms do

Respiratory System

• Mammal lungs have a larger surface area than reptiles and amphibians
• Mammals can exchange more oxygen and carbon dioxide in each breath

Circulatory System

• Mammals have a four-chambered heart
  • A septum completely divides the ventricle
• The left ventricle pumps oxygen-rich blood to the body
• The right ventricle pumps oxygen-poor blood to the lungs
• Only the oxygen-rich blood is delivered to the tissues

Types of Teeth

• Most mammalians have four types of teeth
• Each type of tooth performs a different function
  1. Incisors - Biting and cutting (Front teeth)
  2. Canines - Used for stabbing and holding (behind incisors)
  3. Premolars – Crushing and grinding (line the jaw)
  4. Molars- Crushing and grinding (line the jaw)

• Three auditory osscilces

Parental Care

• Young mammals depend on their mother for a relatively long period of time - They receive milk and other food - Milk is produced in the mammary glands, which are located on the female’s chest or abdomen - Protection - shelter