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.

Digestion

A 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.

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.

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