Download Characteristics of Mammals

MAMMALS
DR. U P K EPA
DEPARTMENT OF ZOOLOGY & ENVIRONMENTAL
MANAGEMENT
Course code : ZOOL 1201
Learning outcomes of this lecture series:
At the end of this course, the student will be able
to describe the diversity of form and function of
mammals and discuss their evolutionary trends
Class Mammalia
•Includes 4000 species
•Most dominant land animals on earth.
Key Characteristics of Mammals
• All mammals have the following in common:
– Are endothermic
– Hair
– Specialized teeth
– Females produce milk in mammary glands to
nourish live young
Mammals and Hair
• Mammals are the only animals that have hair
• Primary function of hair is insulation
• Other functions of hair include:
– Helping animals blend into their surroundings
– Using its hair for advertising
• Black and white hair on a skunk warns predators to stay
away
– Specialized hair serve as a sensory function
• Whiskers on cats and dogs are sensitive to touch
Endothermy
• Mammals are endothermic (warm-blooded)
– Are animals that can maintain a constant body
temperature despite the changes in the
environment
• Endothermy allows animals to live in cold
environments
Endothermy
• Endothermy enables mammals to be very
active
• Movement for long periods of time requires a
lot of energy and a high metabolism
– A mammal needs to eat 10x as much food as an
ectotherm of similar sizes
– Metabolizing food requires a lot of oxygen
Endothermy
• The respiratory and circulatory systems of
mammals are adapted to endothermy
• They acquire and distribute oxygen more
efficiently than the respiratory and circulatory
systems of ectoderms do
Respiratory System
• Mammal lungs have
a larger surface area
than reptiles and
amphibians
• Mammals can
exchange more
oxygen and carbon
dioxide in each
breath
Respiratory System
• The Diaphragm aids
mammals in breathing
– The diaphragm is a sheet
of muscle that separates
the chest cavity from the
abdominal cavity
– When the diaphragm
contracts , the chest cavity
enlarges and air is drawn
into the lungs
Circulatory System
• Mammals have a four-chambered heart
– A septum completely divides the ventricle
• The left ventricle pumps oxygen-rich blood to
the body
• The right ventricle pumps oxygen-poor blood
to the lungs
• Only the oxygen-rich blood is delivered to the
tissues
Specialized Teeth
• Mammals eat many types of food
• Mammals have specialized teeth that reflect
the difference in their diets
• Mammalian teeth are continually lost and
replaced
• Mammalians usually only have two sets of
teeth
– Baby Teeth = the first set
– Permanent Teeth = the second set (not replaced)
Types of Teeth
• Most mammalians have four types of teeth
• Each type of tooth performs a different function
1. Incisors - Biting and cutting (Front teeth)
2. Canines - Used for stabbing and holding (behind
incisors)
3. Premolars – Crushing and grinding (line the jaw)
4. Molars- Crushing and grinding (line the jaw)
• Mammals have single lower jaw
• Three auditory osscilces
Parental Care
• Young mammals depend on their mother for a
relatively long period of time
– They receive milk and other food
• Milk is produced in the mammary glands, which are
located on the female’s chest or abdomen
– Protection
– shelter
Parental Care
• All mammals reproduce by internal
fertilization
• Mammals differ in how and where their
fertilized eggs develop
• Mammals are classified into three groups
based on their pattern of development
1. Monotremes
2. Marsupials
3. Placental Mammals
Movement
• Mammals use various modes of locomotion,
including running, hopping, climbing, flying,
burrowing, and swimming
• Adaptations in body structure help mammals
move around in their particular environments
Response
• Mammals rely on their senses- vision,
hearing, smell, taste, and touch- for survival
• The importance of a given sense depends on
the animal’s lifestyle
• Example:
– Bats and Dolphins live in different locations but
both use echolocation
• Echolocation is the process of using reflected sound
waves to find objects
Answer the following…
• What are three functions of hair?
• Why does a mammal need to eat more food
than a reptile of similar size?
• What type of tooth is used for stabbing a
holding ?
• What group of mammals lay eggs?
• What are the types of locomotion that
mammals use?
Class Mammalia
• Subclass Prototheria- extinct mammals with
unique skull structure
• Subclass Theria- Living mammals distinguished
by skull
• Infraclass Ornithodelphia- Monotremes
• Infraclass Metatheria- Marsupials
• Infraclass Eutheria- Placentals
Classification:
Class: Mammalia:
Subclass:
Infraclass:
Prototheria
Theria
Ornithodelphia Metatheria
Order:
Monotremata
Marsupialia
Theria
Eutheria
19 orders
12
Order Monotremata
• Oviparous or egg laying mammals
• Only 3 in existence
• Duck-billed platypus and two species of spiny
anteaters called echidna.
• Not completely endothermic (their body
temperature is lower and fluctuates more than
other mammals)
• Mammary glands without nipples
• Edentulous as adults; No teeth
• Limbs modified for swimming or digging
• Australia and New Guinea
Duck-Billed Platypus
Ornithorhynchus
• Only member of the mammal family
Ornithorhynchidae
• Several reptilian characteristics: same opening for
reproduction and eliminating waste products, the
ability to lay eggs
• The world's only venomous furred animal
– Spur on hind foot
– Females loose after one year
• Bill contains an electro-receptor system
30
WHAT ARE THE ADAPATATIONS SEEN IN THE HEAD OF
PLATYPUS FOR AQUATIC MODE OF LIFE?
THIS PICTURE SHOWS THE HIND LEG OF MALE PLATYPUS. IDENTIFY AND
STATE THE FUNCTION OF THE RED COLOURED ORGAN.
POISON LAND
THICK, WATER
PROFF FUR
KEEPS EYES, EARS
& NOSTRILS
SHUT
ELECTRO
RECEPTORS
SINGLE
OPENING FOR
ANUS & URINOGENITAL SYSTEM
LAYS EGGS
WEBBED FEET
TOOTHLESS MOUTH & BEAK
LIFE OF PLATYPUS
World's Strangest Creature?
Part Mammal, Part Reptile
Platypus is a……
• Predator of:
Small frogs
Insects
Worms
Cray fish
• Prey of:
Tasmanian devils
Crocodiles
Sharks
Echidna (Spiny Anteater)
Tachyglossus aculeatus
• "Echidna" derives from the Latin word
for "viper”
– Tongue protrudes like a snake
• Nocturnal
• Terrestrial and burrowing
• They have very tough spines that cover
the top of the body.
Can you tell the adaptations seen
for terrestrial mode of life?
What do you think of its hair
distribution?
• Echidnas are
solitary
animals and
live in
burrows.
• When
attacked, the
echidna will
quickly
burrow into
the ground or
curl up into a
ball.
• A single egg is laid
in a pouch that
sticks to the
mother’s belly.
• Baby echidnas are
born blind and
hairless.
• Young suckle in the
pouch for about 55
days which is when
they start getting
too prickly!
• Lactation goes for
• Echidna spines
are very long.
• They also have
long, sharp claws
on the feet and a
very sensitive
snout.
• There are 2 types
of echidna: long
nosed and short
nosed.
• Echidnas are
insectivores.
• They use their
long, sticky
tongue to catch
ants, termites,
other insects,
and
earthworms.
What are the adaptations of insectivorous mammalas…?
See the Claws……..
Endangerment
Hunted with
trained dogs.
• Loss of natural forest
habitat due to farming.
How can the echidna be conserved?
• Prohibit hunting.
• Establish wildlife reserves for
them.