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?