Bio 123: PP20 Material Flashcards
What falls under the Class Mammalia?
They are all sub classes*
-Monotremata
-Marsupialia
- Plancentalia
What is the unifying characteristic of mammals?
They can all produce milk and have mammary glands in which they use to nourish their young
Diversity of Mammals
-5500 species
-originated in the Triassic Era but their diversity was limited until the Cenozoic Era
-They all lactate to feed their young
- Half of the mammal diversity is made up of rodents
- Have a huge morphological diversity (bats v. whale v. Giraffe v. Mole)
What is the second largest group of mammals?
The Chiroptera! These are the bats
What is the first largest group of mammals?
The Rodentia! Includes 2,200 species
Monotremes Characteristics
Lack nipples and instead part of their skin is modified into mammary glands and their young directly such on their skin to get milk. Monotremes are also oviparous
Marsupials
- Have nipples
-Have very short gestation periods
-Their development is completed in their mother’s pouch
Placental Mammals
-Young are developed in the placenta
Laundry list of mammals
-Have hair
-Have glandular skin that includes sweat, scent, sebaceous, and mammary glands
-Have middle ear bones
-Have diphydont teeth that are either homodont or heterodont
-Have moveable eyelids
-Have fleshy external ears
-Four chambered heart
-Non nucleated biconcave red blood cells
-Alveolar lungs
-Defined larynx
-Paired kidneys with urinary bladder
-Have more complex brain development (cerebral cortex)
-Young are nourished by milk from the mammary glands
Sweat glands
Used for temperature control and to regulate internal body temp
Scent glands
Used to attract mates
Sebaceous Gland
Secretes sebum to help keep the skin moist
What are the middle ear bones of mammals divided?
The middle ear bones are the smallest bones in the body of a mammal. The middle ear bones are split into the incus, malleus, and stapes
Homodont teeth
Teeth that are all pretty much the same shape/size throughout. E.G. elephants have mostly all molars used to grind down their specific diet
Heterodont teeth
Having different types of teeth throughout. E.G. dogs have canines, molars and incisors
Why do mammals have non nucleated biconcave red blood cells?
To make more room to carry oxygen
Alveoli
Little air like sacs where gas exchange take place in the lungs. MAIN PURPOSE IS TO EXPAND THE SURFACE AREA FOR GAS EXCHANGE TO OCCUR
What is the purpose of having paired kidneys?
Used for excretion
Cerebral cortex
Responsible for conscious thought
Characteristics of Monotremes
-5 species
-Includes the duck-billed platypus
-Do not have birth to live young (oviparous mammals)
-Eggs hatch rapidly which is followed by lactation in the mother.
-No nipples
-Lactation occurs through a specialized patch of skin
Unique characteristic of the Duck-billed platypus
It have a venomous spur which is mainly used for predatory defense. It is one of the only mammals that contains venom.
Characteristics of Marsupials
-Includes the koalas, kangaroos, and tasmanian devils
-Major characteristic is that they give birth to very premature offspring that are not fully developed and complete their development in the mother’s pouch
-Have a placenta
-Have very short gestation period
Gestation period
The time in which the developing embryo is developing in the placenta of its mother.
Development of Marsupials
-Born extremely early
-Climb up the fur of its mom and attaches to a nipple in the pouch
-Embryo = “Clawing head”
-Never detaches during its brooding period
-Once detaches they are called a ‘joey’ but still mainly stay in pouch until weaning
Marsupials in U.S
The only marsupial in the US is the North American Possum
Reliance on Parental Care
Mammals and birds and the two groups that majorly depends on parental care
Placental groups
-Mothers have a placenta that directly nourishes the developing fetus
-Are all viviparous (give birth to fully developed young)
-Some are altricial/some are precocial
-Gestation period in placental groups are much longer
What falls under placental groups?
- Pholidota (Pangolin)
-Rodentia (rodents) - Lagomorpha (rabbits)
-Chiroptera (bats)
-Carnivora (cats, dogs, bears)
-Ungulates (hoofed mammals including sea mammals)
-Primates (lemurs, apes, humans)
Pangolin
Have a reversal to scales and is the most ancient group of mammals
Ungulate digestion
-Have specializations in their digestive track for the efficient break down of plants (plants are hard to break down and get nutrients from because of its cell wall)
Purpose of the small intestine
to absorb nutrients
Purpose of the large intestine
main job is to absorb water
Stomachs of deer, cows, and goats
They have a multi chambered stomach that aids in the process of breaking down plant material to get nutrients
Ruminant stomach
-Have a reticulum which is a muscular chamber that is used to further grind down plants
Digitgrade
Primarily walks on their digits (dogs)
Plantigrade
Walks on the soles of their feet (humans)
Unguligrade
Walk on hoofed feet (horses)
Sociality in Mammals
-They have more complex brain and therefore have more complex behavior and have modifications to their behaviors through learning
Define Sociality
The tendency to form social groups or live in structured groups
Advantages of Sociality
1) Increases hunting success: groups may be able to exploit resources not available to single individuals
2)Predator defense: increased detection of predators and less time invested to search for predators, gives more time for eating
3) Increases reproductive fitness
Where is sociality common?
Common in birds and mammals. Most primates form social groups
Disadvantages of sociality
1) Disease transmission
2) Scarce resources and potential for increased competition among individuals which can increase fighting
Primates
-Have complex brains
-Have complex social and behavior structure
-Understand reciprocity
-Understand fairness
Altruism
Selfless act
