Download CHAPTER 32 Characteristics of the Class Mammalia are: have hair

CHAPTER 32
Characteristics of the Class Mammalia are: have hair, use mammary glands to nurse their young with milk, breathe air, have 4
chambered hearts, and are endotherms.
Body Temperature Control: Mammals are endotherms, and their high metabolism rate helps regulate their internal temperature. Hair
and fat layers also help. Sweat glands help cool the body via evaporation. Those that lack sweat glands pant (like dogs).
Feeding: Because of their high metabolic rate, mammals must eat 10 times as much food as a reptile of the same size. Well developed
jaws. Modern mammals have specialized teeth- incisors, canines, molars, and premolars. The shape and function varies based on
herbivores/carnivores.
Carnivores have a shorter digestive tract than herbivores. Some herbivores, such as cows, have a special stomach chamber called a
rumen that has bacteria to break down plant fiber. After series of swallowing the food, processing it in the rumen, regurgitating it, and
swallowing again for further processing, the food moves into the stomach.
Respiration: All mammals, including aquatic ones, have lungs and must breathe air.
Circulation: Two loops with a 4 chambered heart. Right side of the heart receives oxygen poor blood and takes it to the lungs. Oxygen
rich blood enters the left side of the heart and is then pumped to the rest of the body.
Excretion: Highly developed kidneys filter urea from the blood, and excrete or retain water as needed. Kidneys are what help
mammals live in deserts where water is scarce.
Movement: Flexible spine and shoulder/pelvic girdles allow for highly varied movement.
Response: Very highly developed brains with 3 main parts: cerebrum for thinking and learning, cerebellum to control muscular
coordination, medulla oblongata to regulate involuntary body functions (heart rate, breathing, etc..)
Reproduction: Internal fertilization. Young are cared for by one or both parents.
3 groups of mammals based on reproduction:
1. Monotremes: Platypus and echidna. Found only in Australia and New Guinea. Reproduction is similar to reptiles- they lay eggs.
They also have a cloaca like reptiles. Monotreme= one opening. Young nurse on mother's milk.
2.Marsupials: Kangaroos, koalas, wombats, possums. Bear live young that complete their development in an external pouch.
Undeveloped young crawl to the pouch and attach to a nipple. Once there, young completes development over several months.
3. Placental Mammals: Most mammals. Nutrients, oxygen, carbon dioxide, and wastes are exchanged between embryo and mother
thru the placenta. Allows for longer development inside of the mother.
Primates and Human Origins
Primates have binocular vision (ability to merge visual images from both eyes to gain depth perception and a 3D view), well
developed cerebrum(complex behaviors), relatively long fingers and toes, and arms that can rotate in their shoulder joints (flexible
digits allow for climbing, swinging, and holding objects firmly).
Evolution of Primates: Primates that evolved from two of the earliest branches look very little like typical monkeys and are called
prosimians. Monkeys, apes and humans are called anthropoids.
-Prosimians: Small, nocturnal primates with large eyes. Many have doglike snouts.
-Anthropoids: Humanlike primates (and humans). Split into 2 major branches:
1. New World Monkeys: Central/South America. Mainly tree dwellers with long arms and a prehensile tail that can coil around
branches and act as a 5th hand.
2. Old World Monkeys: Africa and Asia. No prehensile tail. Great apes, also called hominoids, include orangutans, gorillas, chimps,
and humans. Chimpanzees are our closest living relative- we share 98% of the same DNA!
Hominid Evolution: Between 6-7 million years ago, the branch that led to the ancestors of modern humans evolved. Major
developments were bipedal (two foot) locomotion, opposable thumb (to grasp objects and use tools), and increase in cerebellum size.
Genus Australopithecus: 4-1 million years ago. Bipedal apes. Mainly ate fruit. Best known species is A. afarensis.
Genus Paranthropus: Huge grinding back teeth to eat plants like modern gorillas.
Hominid evolution did not proceed by the simple, straight line transformation of one species to another. Rather, like the evolution of
other mammalian groups, a series of complex adaptive radiations produced a large number of species whose relationships are difficult
to determine.
Genus Homo: Appeared about 2.5 million years ago. H. habilis was found in Africa with tools. H. erectus was probably the first to
leave Africa and move into Asia. Not sure where H. sapiens arose, but probably in Africa 200,000-150,000 years ago and then
migrated out. Scientific debate, and the search for more data, continues.
Modern Homo sapiens: H. neanderthalensis in Germany. Made tools and lived in social groups. H. sapiens joined the H.
neanderthalensis in the Middle East around 100,000 years ago and lived together for about 50,000 years. H. sapiens made more
sophisticated tools, cave paintings, buried their dead. 30,000 years ago, Neanderthals disappeared (unknown). We are the only species
of hominid now.
CHAPTER 34
Behavior: The way an organism reacts to changes in its internal condition or external environment. Like turning your head in the
direction of a noise.
Stimulus: Any kind of signal that carries information and can be detected. If you're hungry, your stomach may growl. Your phone
ringing and you run to answer it.
Response: A single, specific reaction to a stimulus. Like waking up when you hear an alarm. A behavior may consist of more than one
response.
When an animal responds to a stimulus, body systems, including sense organs, nervous system, and muscles, interact to produce a
behavior.
Two types of behaviors:
-Innate Behavior: Appear to be fully functional the first time they are performed. No previous experience with the stimuli is needed. A
complex interaction between genes and environment. Newly hatched birds begging for food. A spider building its first web.
-Learned Behavior: Behaviors altered as a result of past experiences (learning). 4 types:
1. Habituation: When an animal decreases or stops its response based on repetitive stimulus that neither rewards or harms the animal.
Ducks in a small pond at a park are scared of people and fly away when approached. They become used to humans over time as they
interact with them, and as people feed them, causing them to realize that the humans are not a threat.
2. Classical Conditioning: An animal makes a connection between a stimulus and some kind of reward or punishment.
3. Operant Conditioning: When an animal learns to behave in a certain way through repeated practice, in order to receive a reward or
avoid punishment. Classical type of animal training.
4. Insight Learning: Most complicated form of learning. Animal applies something it already learned to a new situation, without a
period of trial and error. For example, if you are given a new math problem on an exam, you use math principles you already know to
solve this new problem that you have never seen.
Instinct and Learning Combined: Most behaviors are a result of innate ability and learning. Young sparrows have an innate ability to
recognize their own species' song, but must learn the full song from adults. Imprinting is when animals (ducks, geese) recognize and
follow the first moving object they see as the mother. Once imprinted, the behavior won't change. Innately, they know to follow the
first thing they see (mother), but they don't know what that "mother" should look like when they are born.
Courtship behavior is a part of an overall reproductive strategy that helps animals identify healthy mates.
Social Behaviors: Often, members of a society are closely related to one another. Helping a relative survive increases the chance that
the genes an individual shares with that relative will be passed along to offspring. Primates form some of the most complex societies.
Hunt together, travel together, interact with neighboring societies.
Competition and Aggression: Competition is reduced among the same species in many animals with the use of individual territories,
each of which has everything that animal needs to survive. Rivals who come into another's territory may be attacked. Generally, the
most aggressive animals will have the best territories and choice of mates.
Communication: Passing information from one organism to another. 4 main types:
1. Visual signals- Cuttlefish can change colors and patterns on its body for defense, hunting, mating, warning, etc...
2. Chemical signals- Some release chemicals, such as pheromones, to mark territory or signal readiness to a mate.
3. Sound Signals- Crickets, toads, birds, dolphins. Use sound to communicate with others.
4. Language- Most complicated form of communication. Combines sounds, symbols, or gestures. Humans are the only animals known
to use language.