1. Mammals!
Ch 32 Turboblastin’

2. What is a mammal?
All mammals are endothermic (maintain a constant body temp)
Can live in almost every possible environment on Earth
Four-chambered heart
Hair covering much/all of body
Produces milk to nurse young
Diaphragms (expand/contract to bring air into lungs)
Specialized teeth
Modified limbs
Highly developed brains

3. All that hair… Maintaining constant body heat takes energy
Having bodies covered in hair minimizes that expense, retain that heat
If body becomes too warm, internal feedback mechanisms help mammals cool off
(panting, sweating, wet noses/mouths)
Sweat glands help regulate body temp by secreting moisture, which evaporates & transfers heat to the surrounding air
Hair – modified into different lengths/textures
Provide camouflage, signaling, protection

4. Mammals nurse their young
Mammals (Gr: mamma = “breast”) secrete milk from glands (a group of cells that secrete fluids)
Also have glands that produce oil, saliva, digestive enzymes, hormones, scent, milk, etc.
Mammary glands (possibly modified sweat glands) secrete liquid rich in fats, proteins, sugars, minerals & vitamins
Mothers nurse young until babies can digest & absorb nutrients from solid foods
Nursing time varies among species

5. Respiration & Circulation
Mammals need a high level of energy to maintain their endothermic metabolism
Diaphragm involuntarily controls lung expansion in chest cavity
4-chambered heart
Remove metabolic wastes with kidneys efficiently

6. Specialized teeth Mammals have teeth with different functions
Adapted to the types/variety of foods they eat
(like having multiple tools in a toolbox for different tasks)
Incisors – grasping, chiseling
Canines – puncturing, tearing
Premolars & molars – slicing, shearing, crushing, grinding
Teeth are first step in mechanical digestion (breaking down food into smaller parts for chemical digestion)

7. Modified limbs
Limbs adapted for variety of food gathering, protection, & locomotion functions

8. Mammals can LEARN Fiercely guard young, teach them survival skills
One reason mammals are very successful
Primates & cetaceans among the most intelligent animals
Use tools, communicate culture to offspring, communication
Complex nervous systems, highly developed brains, varied & specialized sensory organs to learn about/interact with surrounding environment

9. Mammal Diversity
Monotremes – egg-laying mammals (platypus, echidna) have cloaca & milk-secreting pores
Marsupials – pouched mammals, young develop somewhat in mother’s body, then complete development/nurse in pouch of skin
Placental mammals – give birth to young that have developed inside uterus
Nourishment from placenta
This development time is called gestation
Most successful group of mammals (90% of all mammals)

10. Origins Placental mammals appeared in fossil record 125 mya
Mammalian characteristics shared by reptilian ancestors called therapsids
Mass extinction of the
dinosaurs along w/ breaking
apart of Pangaea and changes in climate led to new niches for mammals to fill
Dramatically increased in # and diversity during the Cenozoic Era (present era)