Mammals Section 1 Characteristics of Mammals Preview Bellringer

Mammals Section 1: Characteristics of Mammals Preview • • Bellringer Key Ideas Key Characteristics of Mammals Endothermy Specialized Teeth Parental Care Movement and Response Summary

Mammals Section 1 Bellringer Make a list of all the mammals that you can think of. What makes the animals on your list different from birds, reptiles, or other groups of animals?

Mammals Section 1 Key Ideas • What are the key characteristics of mammals? • How are the respiratory and circulatory systems of mammals adapted for endothermy? • What do specialized teeth reveal about mammals?

Mammals Section 1 Key Ideas, continued • How do mammals differ from other vertebrates in terms of parental care? • What types of locomotion do mammals exhibit?

Mammals Section 1 Key Characteristics of Mammals • What makes a mammal? • Mammals are endothermic, they have hair and specialized teeth, and females produce milk in mammary glands to nourish their young. • Mammals are the only animals that have hair. • Even whales and dolphins have a few small, sensitive hairs on their snouts.

Mammals Section 1 Key Characteristics of Mammals, continued • The primary function of hair is insulation. • Hair can also help a mammal blend in with its surroundings. • The hair of some mammals, such as arctic foxes, changes from white in winter to brown in summer.

Mammals Section 1 Key Characteristics of Mammals, continued • The black and white hair of a skunk warns predators to stay away. • The thick mane of a male lion advertises how strong the lion is. • In some mammals, specialized hairs such as whiskers serve a sensory function.

Mammals Section 1 Visual Concept: Characteristics of Mammals Click the button below to watch the Visual Concept.

Mammals Section 1 Endothermy • Like birds, mammals are endotherms, animals that generate heat internally through metabolism of food. • Unlike most amphibians and reptiles, mammals can live in very cold climates. • Endothermy enables mammals to become very active.

Mammals Section 1 Endothermy, continued • Flying and running require a lot of energy and a high metabolism. • A mammal needs to eat about 10 times as much food as an ectotherm of similar size does. • Metabolizing food requires a lot of oxygen.

Mammals Section 1 Endothermy, continued • 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 ectotherms do. Respiratory System • The lungs of mammals have a larger internal surface area than do those of reptiles or amphibians.

Mammals Section 1 Endothermy, continued • Mammals can exchange more oxygen and carbon dioxide in each breath then reptiles or amphibians can. • Respiration in mammals is aided by the diaphragm, 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.

Mammals Endothermy, continued Circulatory System • Like birds, mammals have a four-chambered heart. • A septum completely divides the ventricles. Section 1

Mammals Section 1 Endothermy, continued • The left ventricle pumps oxygen-rich blood to the body, while the right ventricle pumps oxygen-poor blood to the lungs. • Only oxygen-rich blood is delivered to the tissues, a condition vital for meeting the oxygen needs of endotherms.

Mammals Section 1 Specialized Teeth • Unlike most other animals, mammals have specialized teeth that reflect the differences in their diets. • A mammal also usually has only two sets of teeth during its life. • Baby teeth are replaced by permanent teeth, which are not replaced if lost or damaged.

Mammals Section 1 Specialized Teeth, continued Types of Teeth • Most mammals have four types of teeth. • Incisors, the front teeth, are used for biting and cutting. • Canines, next to the incisors, are used for stabbing and holding. • Premolars and molars, at the sides and back of the mouth, are used for crushing and grinding food.

Mammals Section 1 Specialized Teeth, continued • One can learn a lot about what mammals eat by looking at the teeth. • A carnivore, such as a coyote, has long canine teeth that are suited for grasping prey. • Carnivores also have sharp molars and premolars that can cut off pieces of flesh.

Mammals Section 1 Specialized Teeth, continued • An herbivore, such as a deer, has small, incisor-shaped canines. • It uses its incisors and canines to nip off pieces of plant material. • Its premolars and molars are flat and covered with ridges that form a surface on which plant material can be ground.

Mammals Section 1 Visual Concept: Types of Teeth Click the button below to watch the Visual Concept.

Mammals Section 1 Parental Care • Unlike the young of other vertebrates, young mammals depend on their mother for a relatively long period of time. • They receive milk and other food, protection, and shelter from her. • Mammals nourish their young with milk produced in mammary glands, which are located on the female’s chest or abdomen.

Mammals Section 1 Parental Care, continued • All mammals reproduce by internal fertilization, but mammals differ in how and where their eggs develop. • Mammals are classified into three groups based on their patterns of development. Monotremes • Monotremes are oviparous, which means they reproduce by laying eggs.

Mammals Section 1 Parental Care, continued • The eggs hatch quickly, and the monotreme mother stays with and nurses the young for several months. • The only living monotremes are the duckbill platypus and echidnas. Marsupials • Marsupial embryos remain inside their mother for only a few days or weeks.

Mammals Section 1 Parental Care, continued • Then, the young marsupial crawls out of the mother, up the fur on her belly, and to her nipples, which are usually located inside a pouch. • A young marsupial completes its development inside the mother’s pouch. Placental Mammals • Placental mammals complete their development inside the mother.

Mammals Section 1 Parental Care, continued • A structure called the placenta attaches the fetus to the mother and allows the exchange of nutrients, oxygen, and wastes. • The period of time between fertilization and birth is called the gestation period. • Some placental mammals, such as horses, can move around or even run shortly after birth.

Mammals Section 1 Visual Concept: Function of a Placenta Click the button below to watch the Visual Concept.

Mammals Section 1 Movement and Response • Mammals use various modes of locomotion, including running, hopping, climbing, burrowing, flying, and swimming. • Adaptations in body structure help mammals to move in their particular environment.

Mammals Section 1 Movement and Response, continued • Mountain lions have powerful limbs for running and jumping. • A bat’s front limbs are modified into wings for flight. • The limbs of dolphins and whales are adapted for swimming.

Mammals Section 1 Movement and Response, continued • Mammals rely on their senses—vision, hearing, smell, taste, and touch—for survival. • The importance of a given sense depends on a mammal’s lifestyle and habitat. • Bats and dolphins both use sound to sense their environments, in a process called echolocation.

Mammals Section 1 Visual Concept: Echolocation Click the button below to watch the Visual Concept.

Mammals Section 1 Movement and Response, continued • They make high-pitched clicks that spread through air or water. • When the sound waves hit an object, such as a moth or a fish, the waves bounce back to the bat or dolphin. • The bat or dolphin can use these sound echoes to find their prey or obstacles in the environment.

Mammals Section 1 Summary • Mammals are endothermic, they have hair and specialized teeth, and females produce milk in mammary glands to nourish their young. • The respiratory and circulatory systems of mammals are adapted to endothermy. • Mammals have specialized teeth that reflect the differences in their diets.

Mammals Section 1 Summary, continued • Young mammals depend on their mother for a relatively long period of time. They receive milk and other food, protection, and shelter from her. • Mammals use various modes of locomotion, including running, hopping, climbing, burrowing, flying, and swimming.