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Class Mammalia
Jess Ackerman
Maddy Smith
• Phylum name: Chordates
• Subphylum: vertebrata
• Class: mammalia
• Common Name: mammals
General Characteristics
• Hair (insulation and protection)
• Sweat glands
– Mammary glands (produce milk for young)
• Differentiation of teeth (incisors, canines,
premolars, molars)
• 3 middle ear bones (malleus, incus, stapes)
• Jaw (composed of dentary and squamosal)
Endotherms (constant body temperature)
• Complex nervous system
• Bilateral Symmetry
Various Body Systems
System Type
Mammals System
Muscular-Skeletal
A mammal has an inner skeleton. It has
developed muscles and generally have four
limbs attached.
Digestion
A mammal has a developed digestive tract with
mouth, teeth, stomach, intestines. Herbivores
eat plants, carnivores eat meat and omnivores
eat both.
Nervous
A mammal has a highly developed brain, nerves
and sensory organs such as eyes, nose, mouth,
ears and touch.
Circulation
A mammal has a four chambered heart, blood
vessels and blood within their system.
Respiration
A mammal has lungs and breathes in oxygen
and gives off carbon dioxide.
Reproduction
A mammal reproduces sexually with the female
being fertilized by the male internally. Mammals
have live birth and care for their young for quite
a time after birth.
Excretion
A mammal gas kidneys and is covered with
skin. The skin has hair. Mammals are warm
blooded.
Symmetry
A mammal has bilateral symmetry.
Coloration
A mammal can be various shades of brown,
black, tan, white.
Anatomy: Skeletal System
• Internal skeletal system
• Seven cervical vertebrae
(normally)
• Four limbs (usually);
limbs adapted for:
– climbing
– swimming
– flying
– running/walking
Anatomy: Respiratory System and Gas
Exchange
• Take in oxygen, expel carbon dioxide
• Lungs:
– Spongy texture
– Epithelium (larger surface area)
• Muscular Diaphragm:
– Drives breathing
– Divides thorax from abdominal cavity
• Air enters through oral and nasal cavities
• Flows through larynx, trachea, and bronchi
• Air is sucked into or expelled out of lungs
– Moves down pressure gradiant
– Aka “bellows lungs”
• Red blood cells serve as oxygen transports
• Four chambered heart pumps blood throughout body
Anatomy: Integumentary System
• Three layers: epidermis, dermis, hypodermis
• Epidermis:
–
–
–
–
Ten to thirty cells thick
Provides waterproof layer
Outermost cells constantly lost
Bottommost cells constantly dividing
• Dermis:
– Fifteen to forty times thicker than epidermis
– Components include bony structures and blood vessels
• Hypodermis:
– Made of adipose tissue
– Stores lipids
– Provides cushioning and insulation
• Hair
Anatomy: Nutrition and Digestion
• Keeping high constant body
temperature is energy expensive
• Need nutritious and plentiful diet
• Different species adapted to dietary
requirements in a variety of ways
– Carnivores (including insectivores)
– Herbivores (granivores, folivores,
fruivores, nectivores, etc.)
• Size of animal is a factor in diet type
– Small: high-energy requirements
– Large: can tolerate slower collection
process or slower digestive process
• Developed digestive tract
– Mouth, teeth, esophagus, stomach,
intestines
Response to Stimuli
• Eyes
– Respond to light, movement, etc.
• Ears
– Responsible for hearing and balance
• Nervous System
– Complex brain (neocortex)
– System of nerves throughout the
body
Anatomy: Reproductive System
• Most are vivipary (live young)
– Metatheria
– Eutheria—placental mammals
– Marsupials—undeveloped young
kept in pouch
• A few lay eggs
– Holotheria (monotremes)
• Mammary glands
– Specialized to produce milk
– Newborns’ primary source of
nutrition
Classes: 3 subclasses
• Holotheria (monotremes, egg laying
mammals)
• Metatheria (marsupials, pouch mammals)
• Eutheria (placental mammals)
Holotheria
• Ex: duck billed platypus, spiny ant eaters
• Reproduction: females lay eggs, or carry in
pouches
• Feeding practices: varied (ant eaters use sticky
tongue, platypus eats freshwater
invertebrates, etc.)
Metatheria
• Ex: kangaroos and opossums
• Reproduction: young are born in undeveloped
stage, complete development in pouch
• Feeding practices: varied
Eutheria
• Ex: humans, lions, etc.
• Reproduction: young remain in mothers until
development is complete
• Feeding practices: varied