Transcript Mammals - GEOCITIES.ws

Mammals
Chapter 43
Monotreme species:
Only 5 living: duck-billed
platypus & 4 species of
echidna (spiny anteaters).
Placental mammals
4000 described species,
mostly rodents and bats
Marsupial mammals
References:
Holt biology text & materials
http://www.ucmp.berkeley.edu/mammal/mammal.html
Objectives for chapter 43
• Describe the major characteristics of mammals.
• Compare the characteristics of early synapsids, early
therapsids, and modern mammals.
• Explain the advantage of endothermy in mammals.
• Differentiate among the patterns of development in
monotremes, marsupials, and placental mammals.
• Recognize the various orders of mammals.
– Mammalian characteristics
All mammals have the following
six major characteristics:
1. Endothermy
2. Hair
3. Completely
divided heart
4. Milk/ mammary
glands.
5. Single jawbone
6. Specialized teeth
– Mammalian characteristics
1. Endothermy
• All Mammals are endotherms which
means they conserve and regulate
body heat.
• allows mammals to remain active in
cold climates.
• enables strenuous activities for
extended periods.
• Requires eating LOTS of food
compared to cold blooded animals.
– Mammalian characteristics
2. Hair
• All mammals have hair- even aquatic ones.
• Insulates against heat loss
• Made of keratin protein filaments
3. Completely Divided Heart
• 4 chambers (2 atria, 2 ventricles)
• Efficient oxygen exchange- no deoxygenated
blood pumped back into body
Mammalian characteristics
4. Milk/ mammary glands.
-All mammals produce milk, High in protein & sugar
-only Monotremes do not have mammary glands but
secrete milk like sweat.
5. Single jawbone.
-lower jaw is 1 solid bone (reptiles have
several bones)
6. Specialized teeth
-teeth modified for different functions
History of MammalsSynapsids & Therapsids
Synapsids – were animals that were small and
looked like modern lizards.
Unlike most other reptiles, which have
uniformly shaped teeth, these early
synapsids had specialized teeth.
Therapsids
• A subset of synapsids, called therapsids, gave rise to
mammals.
• Therapsids appeared late in the Permian period and lived
into the Jurassic period.
– History of Mammals-
History of Mammals
• Mammals and dinosaurs
– appeared during the Triassic period
– coexisted for more than 150 million years.
• Early mammals
– about the size of mice
– probably insectivores
– active at night.
– History of Mammals-
Phylogenetic Diagram of
Vertebrates
Mammals have highly developed &
efficient body systems:
• Circulatory System
• Respiratory System
• Digestive System
– note specialized teeth
– Special Adaptations for Digesting Plants
• Nervous System
• Reproduction
Circulatory System
• 4 chambered heart
• 2 atria, 2 ventricles
– A septum completely
separating the ventricles.
– The complete septum is an
adaptation that allows
mammals’ bodies to use
oxygen more efficiently.
Respiratory System
- efficient gas
exchange.
–larger surface
area available for
gas exchange
–At rest, mammals
breathe mostly with
their diaphragm.
Digestive System
• TEETH: - size and shape of teeth reflect
differences in diet in various species.
– Incisors -Chisel-like cut.
– Canines Pointed grip, puncture, and tear.
– Premolars shear, shred, cut, or grind.
– Molars grind, crush, or cut.
• Carnivores have sharp incisors & long
canines.
• Baleen whales have baleen instead of teeth.
Types of mammalian teeth:
Special Adaptations for
Digesting Plants
• Herbivores have long digestive tracts
• special organs w/ symbiotic
microorganisms, which can break down
cellulose.
– Some have a rumen and are called
ruminants.
– Others have a cecum.
Nervous System
• Big Brains:
– A mammals brain is at least 15X heavier than a similarly sized fish,
amphibian or reptile.
– Humans, other primates, and whales have the biggest brains
cerebrum which is folded for
max surface area.
– due mostly to the size of the
– The cerebrum evaluates input from the sense organs, controls movement,
initiates and regulates behavior, and functions in memory and learning.
• Senses:
– Major senses include vision, hearing, smell, touch &
taste.
– Some animals are more developed in some senses:
example
Most bats, which are active at night, use echolocation to locate prey
and other objects.
There are 3 different kinds of mammals
based on how they give birth:
1.Monotremes are oviparous, they lay eggs.
2. Marsupials are viviparous, they give birth to
live young that further develop within a
mother’s body.
pouch on the
3. Placental mammals also viviparous,
but the fetus typically develops within the mother’s
reproductive system for a longer time & receives
nourishment through blood-rich structure- the placenta.
Mammalian orders:
• Mammals are commonly classified into:
–a single (1) order of Monotremes
–7 orders of Marsupials
–about 18 orders of Placental
mammals
Phylogenetic Diagram of Mammals
Monotremes
• Lay & incubate large eggs
• Mom protects & feeds newborns until able to
survive on their own.
• The order Monotremata, (monotremes) is
the only order in the subclass Prototheria.
• Just 3 species exist today:
– The duckbill platypus is adapted to life around
rivers or streams in Australia.
– Two echidna species live in dry woodlands or
deserts in Australia and New Guinea.
Marsupials
• Embryo develops in the uterus, but when born,
crawls into the mother’s pouch, attaches to a nipple to
feed; develops in the pouch for several months.
• Previously 1 order, but are now divided into at
least 7 orders in the super order Marsupialia.
• Most of 280 species live in Australia,
• Virginia opossum is only marsupial native to USA
• Theory: marsupials began to evolve in isolation when
Australia drifted away from the other continents more
than 40 million years ago.
Placental Mammals
• Placental mammals give birth to welldeveloped young after a long period
of development inside the uterus.
• During this period, the placenta
provides nourishment and oxygen to
developing offspring
Your assignment:
Read pages 868 to 874 in the textbook.
Write down the following orders & give the main characteristics of each Plus at least
2 example organisms:
• Monotremes
• Superorder marsupialia
• Placental mammals in super order Eutheria
– Xenarthra
– Lagomorpha
– Rodentia
– Primate
– Chiroptera
– Insectivora
– Carnivora
– Artiodactyla
– Perissodactyla
– Cetacea
– Sirenia
– Probscidea
– Also the 5 orders in the table 43-1
Then- Answer questions 1-5 on page 874
18 orders of Placental Mammals
Order Xenarthra
• The order Xenarthra includes about 30
living species of anteaters, armadillos, and
sloths living in the Americas.
Order Lagomorpha
• The order Lagomorpha, the lagomorphs,
includes about 70 species of rabbits,
hares, and pikas.
18 orders of Placental Mammals
Order Rodentia
• The order Rodentia, the rodents, is the largest
mammalian order, which includes more than 1,800
species.
• Rodents are adapted to a wide range of habitats
worldwide.
• Squirrels, marmots, porcupines, chipmunks, gophers,
muskrats, mice, and rats are rodents.
Order Primates
• The order Primates is made up of 235 living species,
including lemurs, tarsiers, lorises, monkeys, gibbons,
apes, and humans.
• They live in a variety of terrains; most are omnivores with
complex behaviors.
18 orders of Placental Mammals
Order Chiroptera
• Chiroptera, the bats, are the only mammals
that truly fly.
• More than 900 species live throughout the
world, except in polar environments.
Order Insectivora
• The order Insectivora includes about 390
species of shrews, hedgehogs, and moles.
• Most members of this order are insectivores,
but not all insectivores are members of the
order Insectivora.
18 orders of Placental
Mammals
Order Carnivora
• The 274 living species of the order Carnivora
are distributed worldwide.
• Dogs, cats, raccoons, bears, hyenas, otters,
seals, and sea lions are some well-known
carnivores.
• Most members of this order eat meat. Most are
skilled hunters.
• Aquatic carnivores, known as pinnipeds,
include the sea lions, seals, and walruses.
Hoofed Mammals
•
•
•
Hoofed mammals are ungulates.
Most are herbivores that run quickly.
The two main groups of ungulates are characterized by their foot
structure and by the presence of either a rumen or a cecum.
Order Artiodactyla
•
•
•
Ungulates with an even number of toes are artiodactyls, in the order
Artiodactyla.
Most artiodactyls are ruminants, or animals that have a rumen.
This order includes about 210 species of deer, cattle, giraffes, pigs, and
camels.
Order Perissodactyla
•
•
•
Ungulates with an odd number of toes are perissodactyls, in the order
Perissodactyla.
Perissodactyls have a cecum.
This order includes about 17 living species, such as horses, zebras,
rhinoceroses, and tapirs.
Some Aquatic Mammals
Order Cetacea
• Closely related to Artiodactyla is the order Cetacea, the cetaceans.
• Cetaceans include about 90 species of whales, dolphins, and
porpoises worldwide.
• Cetaceans are totally aquatic but evolved from land-dwelling
mammals.
Order Sirenia
• Four species of manatees and dugongs make up the order Sirenia,
the sirenians.
• These herbivores live in tropical seas, estuaries, and rivers.
• The similarities between whales and sirenians came about through
convergent evolution.
– More mammals
Order Probscidea
• Members of the order Proboscidea have a nose that is
modified into a long, boneless trunk, or proboscis.
• The only living species of this order are the Asian
elephant and the African elephant, which is the largest
living land mammal.
• Mammoths and mastodons are extinct members of this
order.
• Elephants have long gestation periods, and can live to
be 80 years old.
And other orders making up less
than 1% of mammals