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 development1. Monotremes2. Marsupials3. 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?