Biology I

Chapter 35 – Mammals

 

KINGDOM                 ANMALIA

SUBKINGDOM         EUMETAZOA

PHYLUM                    CHORDATA

SUBPHYLUM            VERTEBRATA

CLASS                        MAMMALIA

 

Phylum Chordata

            (fish, birds, reptiles, amphibians, mammals)

 

            Characteristics of Chordates

¨      have a notochord – this develops into a vertebral column

¨      dorsal nerve cord = brain and spinal cord makes up the CNS, (central nervous system)

¨      gill slits

 

                                                Three Subphyla

1.      Urochordata = tunicates

2.      Cephalochordata = amphioxus

3.      Vertebrata = all animals with a backbone

 

Characteristics of Vertebrates

¨      vertebral column = backbone and skull form “Axial Skeleton”

¨      endoskeleton = made of bone and cartilage

¨      has 3 parts

1.      axial skeleton

2.      two girdles

3.      appendicular skeleton

¨      Two girdles = Pectoral and Pelvic

¨      limbs = form appendicular skeleton

¨      three body regions

¨      paired sense organs

¨      Vertebrate Body Systems

1.      Integumentary

2.      Skeletal

3.      Muscular

4.      Digestive

5.      Excretory

6.      Respirator

7.      Circulatory

8.      Immune

9.      Endocrine

10.  Nervous

11.  Reproductive

 

 

7 Classes of Vertebrates

 

1.      Agnatha = “jawless fish”                 (lamprey, hagfish)

2.      Chondrichthyes = “cartilagenous fish”          (sharks, rays)

3.      Osteichthyes = “bony fish”  ( perch, bass, catfish)

4.      Amphibia =   (salamanders, toads, frogs

5.      Reptilia =       ( snakes, lizards, turtles, crocodilians)

6.      Aves =    (all types of birds)

7.      Mammalia = (all mammals)

 

 

Class Mammalia ~

                        4000 species

                        The dominant land vertebrate

 

Characteristics:

 

-         Endothermic- warm blooded

-         *Hair

-         4 chambered heart

-         Diaphragm

-         Single lower jaw bone –(mandible) - 4 different types of teeth

-         *Most viviparous --- they have live births

-         *Mammary glands that secrete milk

 

Therapsid – reptilian ancestor of mammals – oldest mammalian fossil found = 200 mya

 

Specialized teeth - incisors – front 4 – cut, bite                          insert drawing here

                              canine- grip, puncture, tear

                              bicuspid –(2 points) premolars – shear, shred

                              molars - (4 points, flat and large) – grind, crush

 

 

 

19 orders of modern Mammals                                                                         

            1 = marsupials – pouched mammals

            1 = monotremes – egg laying mammals

            17 = placentals – live birth       

           

1.  Order Monotremata                  

-         Oviparous = they lay eggs

-         Only 3 species exist

1.      Duck billed platypus                                                          

2.      Two species of Echidna (spiney anteater)               

            -    Habitat = Australia, New Guinea, Tasmania

-         Not totally endothermic = body temperature fluctuates

 

      2.  Order Marsupialia

            -     Pouched Mammals

-         Birth extreamly immature young that mature in pouch

-         Can only have as many babies as have nipples or the babies die

-         250 species exist:

-         four examples

1.      Opossum – Only American species

2.      Wombat – Looks like ground hog                            

3.      Glider – Looks like flying squirrel

4.      Cuscus – Looks like monkey                                                                     

 

Placental Mammals

-     17 orders

-     95 % of all mammals

-         Carry unborn young in uterus

-          Placenta – baby gets nourishment from mom ( placenta, umbilical cord)

 

-         Gestation – Time period of uterine development

                        ( therefore, varies in length from species to species)

                                                * rabbit = 31 days

                                                * people = 42 weeks

                                                * horses = 11 ½ months

                                                * whales = 2 ½ years

 

 

3.  Order Insectivora

-     Shrews and Moles

-         small

-         high metabolism rate

-         long pointed noses – helpful to eating insects, worms, other invertebrates

 

4.  Order Rodentia

-         Squirrels, Marmots, Chipmunks, Gophers, Mice, Rats, Porcupines in No. Am.  In So. American = Guinea pig, Capybara

-         Largest mammal order

-         2 incisors – continually grow, must be gnawed down or they can kill the animal

-         food – seeds, twigs, roots, bark

 

5.  Order Lagomorpha

-         Rabbits, hares, pikas

-         Double row of incisors

-         Herbiverous

 

6.  Order Edentata

-         Armadillos, sloth,

-         “without teeth”  

-         tongue = sticky and very long, (the better to get insects with)

-         claws = on front paws are very sharp to dig out insects

 

7.  Order Chiroptera

-         Bats

-         * only true flying mammal*

-         claws on thumb = walk, climb, grasp

-         nocturnal

-         echolocation – sounds waves, help them “see” at night

-         small eyes, not very good

-         large ears, great for picking up reflected “sonar”

-         insect diet – mostly fruits and flowers, nectar and insects

-     tropics – flying foxes largest bats known

 

8.  Order Cetacea

-         Whales, dolphins, porpoises

-          Habitat – marine

-         Forelimbs modified to flippers

-         No hind limbs

-         Breath through blowhole

2 groups of cetaceans

a.  Toothed whales

            (Beaked whales, Sperm whales, Beluga whales, killer whales Orca , Dolphins, Porpoises)

            * 100 + teeth

            * carniverous – fish, squid, seals, other whale are food source

b.  Baleen Whales

            (Blue whale, Humpback whale)

            * baleen – finger-like plates = filters the plankton out of water

 

9.  Order Sirenia

            -  Manatees (sailors once thought they were mermaids)

            -  Herbiverous

            -  live in Florida Keys

            -  less than 2000 individuals left

 

10.  Order Carnivora

            -  dogs, cats, raccoons, bears, otters, hyenas

            -  mainly eat meat

            -  long canine teeth

            -  strong jaws

            -  claws (some retractable some always out)

            -  good smell and vision

            -  run quickly (cat family members are some of the fastest mammals on earth)

            -  racoons and bears are also considered omnivours because they also eat berries and fruits                             

 

11.    Order Pinnipedia

-  Sea Lions, Seals, Walrus

            -  water dwelling carnivores

            -  stream line bodies

 

12.  Order Artiodactyla

            -  Deer, Elk, Bison, Moose, Cow, Sheep, Goat, Pig, Camel

            -  hoofed animals with even number of toes

            -  Split hoof = cloven hoof

            -  Defense – speed- fast runners

            -  Herbivores

            * Teeth modified (flat) for grinding

            *  Rumen – storage stomach, has bacteria in it that helps the animal digest  

                plant cellulose 

            *  Cud – the partially digested material that is re-chewed (regurgitated and

                chewed up to 7 times before swallowing permanently)

 

13.  Order Perissodactyla

            -  Horse, Zebra, Rhinoceros, Tapir

            -  hoofed animals with odd number of toes

            -  herbivorous

            * large flat teeth

            *  cecum – sack at the end of the small intestine- contains bacteria that break    

                down cellulose

             

14.  Order Proboscidea

            -  boneless trunked nose = proboscis

only 2 species live today

1.      Asian elephant

2.      African elephant

            -  extinct = wooly mammoth

            -  largest land dwelling mammals today

            -  tusks – modified incisors

            -  can drink 56 gallons of water in 4 minutes

            -  walk on their tip toes

 

15. Order Primates

 

          two types of primates

1.      prosimians - Lemurs, Tarsiers

2.      anthropoids - Humans, Monkeys, Apes, Gorilla

 

-  omniverous- they have specialized teeth

-  large brain/ body size

-  humans – language

 

16.    Order Tubulidentata

-         Aardvarks

-         toothless, tunnel-like mouth

 

17.    Order Hyraciodea

-         Hyraxes

-         look like rabbits but teeth like rhino teeth and they have hooves

 

18.    Order Pholidota

-         Anteaters = only mammals without any teeth at all

-         back and sides covered with scales

-         use tongue to catch insects

 

19.    Order Dermoptera

-         Gliding Lemurs

-         fangs and wide incisors