Mammals

Class Mammalia The name mammalia is derived from mammary glands. These glands produce milk to nourish newborns. Females are the only sex that produce milk, but males also possess these glands. Males just don’t have certain increases of hormones that cause lactation or milk production.

Class Mammalia Hair Mammary glands Sweat glands Muscular diaphragm Endothermic Four chambered heart Two sets of teeth (“baby” and “adult”) Heterodont teeth Different shapes and functions

Class Mammalia Additional characteristics (you don’t need to write these down) Movable eyelids Two occipital condyles Three ear bones Placenta Except two groups

Mammals are endothermic Mammals are endothermic. They maintain a constant internal body temperature. Hair and a subcutaneous fatty layer helps to maintain warmth, while sweat glands help cool.

Movement Backbone that flexes vertically and side to side Variations in limb bones allow walking, running, climbing, burrowing, hopping, swimming, flying, etc.

Basic Mammal

Lion

Rhinoceros

Gorilla

Chimpanzee

Chimp and Human

Bat

Same bones, different stance

Feeding and Digestion Mammals may be herbivores, carnivores, omnivores, or filter feeders (baleen whale). They have specialized teeth Some mammals that eat plant material have specialized organs to break down plant material including a rumen and cecum The mammalian digestive system cannot break down plant material on its own. Symbioitic relationships with bacteria and fungi allow plant material to be digested in mammalian organs.

Incissors

Canine

Premolars

Molars

Grass eaters have different teeth than carnivores

SALIVARY GLANDS DIGESTION starts in the MOUTH Image from: http://www.entnet.org/healthinfo/throat/salivary.cfm

BALEEN Thin keratin plates that hang from the roof of the mouth and screen food from water Image from: http://home.iprimus.com.au/readman/whale.htm

RUMEN In cud chewers like cows, sheep, goats, giraffes First chamber of stomach containing bacteria to digest plants Image from: http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumen_anat.html

CECUM In non cud chewers like horses, rabbits, rodents, elephants Small pouch off small intestine containing bacteria to digest plants

Human Digestive System

Respiration Mammals have a large diaphragm muscle that when contracted, pulls the bottom of the chest cavity downward, increasing the volume of the chest cavity, allowing a mammal to inhale. Air is pulled into the chest cavity and lungs when this happens. When the diaphragm muscle relaxes, the volume of the chest cavity decreases and causes air to be pushed out—exhaling.

Human Respiratory system

Circulatory system Mammals have a two loop closed system (pulmonary and systemic) that is very efficient at transporting oxygen to cells and removing carbon dioxide from cells. 4 chambered heart

Fig. 31.12 Fig. 31.12

Mammal Circulation

Excretory system Mammals have highly developed kidneys that help maintain homeostasis. Kidneys osmoregulate, maintaining water and ion concentrations, as well as removing excess urea or nitrogenous waste from the blood.

Human excretory system

Nervous system and response Mammals have the most highly developed brain of any animal. The three main parts of the mammalian brain are the cerebrum (motor movement, sensory info), cerebellum (balance and coordination), and medulla oblongata (involuntary organ control). Mammals have a cerebral cortex, the center for thinking and complex behaviors Mammals have exceptional senses such as smell, hearing, and eyesight.

Reproduction and development Distinct separate sexes, sexual reproduction, and internal fertilization. Most viviparous (duck billed platypus is oviparous and lays eggs) Young nourished by mother’s milk and usually raised for an extended period of time.

There are 3 general groups of mammals There are 3 general groups of mammals. Include in notes general characteristics for each as well some common examples.

Monotremes Lay eggs Transitional species Incubate 12 days Lick milk from mothers fur

MONOTREMES “Egg laying” Duckbilled Platypus Anteater Echidna

Marsupials Pouched mammals Birth to tiny embryo that is not fully developed Embryo crawls into mother’s pouch to complete development

MARSUPIALS Premature babies develop in pouch Mostly found in Australia/ New Guinea Kangaroo Wallaby

MARSUPIALS Only North American Marsupial Oppossum

Placental Mammals Placenta nourishes embryo inside mother Long gestation period 22 months for elephant Most successful group of mammals

PLACENTAL Embryos nourished inside mother by placenta 95% of all mammals are placental At least 18 orders

Placental Mammals Competitive advantage over monotremes and marsupials Better nutrition from placenta Less vulnerable to predators More advanced at birth

Evolution of Placenta from Amniotic Egg (you don’t have to write down) Reptile Chorion Oxygen from air Amnion Provides private pond Yolk Sac Food for embryo Allantois Store urinary waste Mammal Chorion Form placenta to get oxygen & food from mothers blood Amnion Provides private pond Yolk sac Temporarily make RBCs Allantois Form umbilical cord

Mammal Classification 14 major orders Over 4,000 species About half are rodents Don’t worry about writing down various order names and groups

Order Monotremata Lays eggs Young lick milk from mothers fur

Order Marsupiallia Pouch

Order Insectivora Sharp-snout Small Burrow underground Eat insects

Order Chiroptera Flying mammals Elongated fingers Echolocation

Order Xenarthra Toothless or peg like teeth

Order Carnivora Large canine teeth Teeth adapted to shear flesh

Order Rodentia Chisel-like incisor teeth

Order Lagomorpha Four upper incisors Hind legs adapted for jumping

Bats Only flying mammal Seed dispersal Pollination Control insects

Smallest Mammal Kitti’s hog-nosed Bat Bumble size 1.5 grams

ECHOLOCATION Bats can fly without eyes, but NOT without ears Bats emit high frequency sound waves that bounce off objects Can determine size, distance, direction, speed

Echolocation

Order Cetacea Front limbs modified into flippers No hind limbs Marine

Whales Blue whale 100 feet long, 120 tons Loudest animal– 188 dB 9 story building Loudest animal– 188 dB Sound travels 100’s of miles

Grey Whale

Migrates 12,500 miles

Grey Whale 50 feet long 35 tons Baleen whale Endangered species Sift mud Endangered species

Killer Whale

Blue Whale Baleen whale Eats krill Heart weighs 1000 pounds Tiny crustaceans 400 pounds/day Heart weighs 1000 pounds Size of a Volkswagen Endangered species

Breaching

Killer Whale 12,000 pounds Eat fish, squid, seals and whales 200 pounds/day Swim 30 mph

Humpback Whale

Order Pinnipedia Limbs modified for swimming Marine carnivores

Order Proboscidea Tusks Largest living land mammal

Order Artiodactyla Two or four toes

Order Perissodactyla One or three toes

Order Primates Opposable thumb Binocular vision Write down general characteristics of primates below Opposable thumb Binocular vision Well developed cerebrum Fingers and toes, fingernails usually Arms rotate around shoulder joint Mammary glands reduced to one thoracic pair

PRIMATES Larger Brain Grasping hand with fingernails instead of claws 2 forward facing eyes Includes: Gorillas Monkeys Lemurs

PRIMATES Humans are primates too!

The End

References Content and slides taken from: Seth Garrison the great Professor Dennis Anderson at Oklahoma City Community College Kelly Riedell and her zoology website Prentice Hall Biology 2002 McGraw Hill Zoology 2008