Class Mammalia

Jess AckermanMaddy 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 SystemsSystem Type Mammals System

Muscular-SkeletalA mammal has an inner skeleton. It has developed muscles and generally have four limbs attached.

DigestionA mammal has a developed digestive tract with mouth, teeth, stomach, intestines. Herbivores eat plants, carnivores eat meat and omnivores eat both.

NervousA 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.

ReproductionA 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.

ExcretionA 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