Transcript Characteristics of Mammals

Characteristics of Mammals
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)
Types of Teeth
• Teeth of carnivores:
– Long canine teeth that are
suited for grasping prey
– Sharp molars and premolars
can cut off pieces of flesh
• Teeth of herbivores:
– Small incisor- shaped
canines
– Incisors and canines used
to nip off pieces of plant
material
– Premolars and molars are
flat and covered with
ridges to create a surface
where plants can be
ground
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
Monotremes
• Monotremes are oviparous = reproduce by
laying eggs
• Eggs hatch quickly, and the mother stays with
and nurses the young for several months
• There are only two alive today:
– Duckbill platypus & echidnas
Marsupials
• After fertilization, marsupial embryos remain
inside their mother for only a few days or
weeks
• The young crawl out of the mother, up the fur
on her belly, and to her nipples, which are
usually located inside a pouch
• Completes development inside its mother’s
pouch
Placental Mammals
• Placental Mammals complete their
development inside the mother
• The placenta attaches the fetus of the mother
and allows exchange of oxygen, nutrients, and
wastes
• the period of time between fertilization and
birth is called the gestation period
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 three types of locomotion that
mammals use?