Mammals Section 2 Groups of Mammals Preview Bellringer
Mammals Section 2: Groups of Mammals Preview • • • Bellringer Key Ideas Monotremes Marsupials Placental Mammals Summary Section 2
Mammals Section 2 Bellringer Copy the following categories on a sheet of paper: Terrestrial, Marine, Carnivorous, and Herbivorous. Make a list of mammals that fit into each category.
Mammals Section 2 Key Ideas • What key characteristic sets monotremes apart from all other mammals? • What are the key characteristics of marsupials? • How common are placental mammals, and how does their development differ from the development of monotremes and marsupials?
Mammals Section 2 Monotremes • Monotremes are a small group of mammals found only in Australia and New Guinea. • Monotremes share more traits with reptiles than with other mammals. • Monotremes are also the only living mammals that lay eggs.
Mammals Section 2 Monotremes, continued • Like reptiles, monotremes have legs that sprawl to the side instead of being under the body. • Also like reptiles, monotremes are the only mammals that have a cloaca, a common passageway for the digestive, reproductive, and urinary systems. • Finally, adult monotremes do not have teeth.
Mammals Section 2 Monotremes, continued • Monotremes are mammals because they have hair. • They produce milk to feed young. However, female monotremes do not have nipples. • Instead of nursing, the young lap up milk that oozes from glands located on their mother’s belly. • The only living monotremes are the duckbill platypus and echidnas.
Mammals Section 2 Marsupials • Marsupials include kangaroos, wombats, koalas, and opossums. • The females of most marsupials have a pouch, and their young spend most of their time developing inside this pouch while they nurse and grow. • Marsupials are the most diverse group of mammals in Australia.
Mammals Section 2 Marsupials, continued • Marsupials are also found in South America. • Only one marsupial, the Virginia opossum, is native to North America. • Scientists believe that marsupials probably moved into Australia from South America before the breakup of Pangaea.
Mammals Section 2 Marsupials, continued • At that time, South America and Australia were connected via Antarctica. • After the continents separated, marsupials evolved and diversified in isolation from placental mammals. • The habitats and lifestyles of marsupials in Australia, New Zealand, and nearby islands are similar to those of placental mammals.
Mammals Section 2 Marsupials, continued • Kangaroos and wallabies often live in large groups and, like deer, are herbivores. • Much like monkeys, tree kangaroos are able to climb trees and jump from limb to limb. • Gliders and possums are similar in habits to squirrels.
Mammals Section 2 Marsupials, continued • Some marsupial predators are similar to small cats. • Tasmanian devils are similar to badgers in some ways. • The Tasmanian tiger, a marsupial wolf, was hunted to extinction by European settlers.
Mammals Section 2 Placental Mammals • Placental mammals are the most familiar mammals. • Cats, dogs, cows, horses, and humans are placental mammals. • Placental mammals make up nearly 95% of all mammal species.
Mammals Section 2 Visual Concept: Types of Terrestrial Placental Mammals Click the button below to watch the Visual Concept.
Mammals Section 2 Placental Mammals, continued • The young of placental mammals develop inside the female’s uterus, where they are nourished by nutrients from her blood. • Placental mammals have a longer period of internal development than marsupials do. • The young of most placentals are more developed at birth than the young of marsupials are.
Mammals Section 2 Placental Mammals, continued • There are many types of placental mammals, which vary greatly in size, shape, diet, and habits. • The orders of placental animals and their relationships to each other and the other mammal groups are shown on the following slide. • The characteristics of each major group of placental mammals are also listed on the following slides.
Mammals Phylogenetic Diagram of Mammals Section 2
Mammals Section 2 Placental Mammals, continued Artiodactyla • Includes pigs, camel, deer, antelopes, and cattle • Have an even number of toes within their hooves • Also called ungulates
Mammals Placental Mammals, continued Perissodactyla • Includes horses, zebras, tapirs, and rhinos • Have an odd number of toes within their hooves • Like artiodactyls, also called ungulates Section 2
Mammals Section 2 Placental Mammals, continued Cetacea • Includes whales and dolphins • Have a streamlined body and move through water with a powerful fluke • Have a layer of blubber to keep them warm
Mammals Section 2 Visual Concept: Types of Placental Marine Mammals Click the button below to watch the Visual Concept.
Mammals Section 2 Placental Mammals, continued Rodentia • Includes rats, mice, and beavers • Have teeth that are specialized for gnawing • More than 40% of all placental mammals are rodents
Mammals Section 2 Placental Mammals, continued Primates • Includes humans, apes, lemurs, and monkeys • Most are tree dwellers • Have grasping hands and feet and long arms and legs that aid in climbing • Have excellent eyesight and depth perception
Mammals Section 2 Placental Mammals, continued Chiroptera • Includes all bats • Only mammal capable of flight • Most bats are carnivorous and use echolocation to find insects • Other bats eat fruit or nectar from night-blooming flowers
Mammals Section 2 Placental Mammals, continued Xenarthra • Includes anteaters, sloths, and armadillos • Anteaters use long, sticky tongues to capture insects • Sloths eat mostly leaves • Armadillos have simple teeth and are omnivorous
Mammals Section 2 Placental Mammals, continued Lagomorpha • Includes rabbits, hares, and pikas • Rabbits and hares have long hind legs and are specialized for hopping • Pikas have short limbs and live in mountainous regions of North America and central Asia
Mammals Section 2 Placental Mammals, continued Sirenia • Includes manatees and dugongs • Relatives of elephants • Have front flippers and a flattened tail for swimming • Sometimes called sea cows, sirenians graze on aquatic plants
Mammals Section 2 Placental Mammals, continued Insectivora • Includes shrews, hedgehogs, and moles • Mainly eat insects • Moles have adaptations for burrowing, including short, powerful forelimbs with long claws
Mammals Section 2 Placental Mammals, continued Proboscidea • The order of elephants, the largest land animals alive today • Trunk is an elongated nose • Upper lip can be used for picking up food, water, and objects • An elephant’s tusks are modified upper incisors
Mammals Section 2 Placental Mammals, continued Carnivora • Cats, dogs, foxes, bears, raccoons, pandas, and hyenas are carnivores • Long canine teeth are specialized for capturing prey and tearing flesh • Some carnivores eat more than meat. Raccoons and bears are omnivores, pandas are herbivores
Mammals Section 2 Placental Mammals, continued Domestic Mammals • Domestic animals are animals that have been kept and bred by people for special purposes. • Domestic animals may provide work, food, clothing, or companionship. • Most domestic animals are placental mammals whose association with humans dates back at least 2, 000 years.
Mammals Section 2 Placental Mammals, continued • Domestic animals include dogs, cattle, horses, donkeys, mules, rabbits, sheep, goats, pigs, camels, llamas, and alpacas. • Various breeds of domestic mammals have been developed through selective breeding. • For example, some breeds of goats produce more milk than others.
Mammals Section 2 Placental Mammals, continued • Other goats, such as angora goats, are bred for their fine hair, which is spun into yarn. • Some domestic mammals are hybrids of two species. • Mules, for example, are the offspring of a female horse and a male donkey.
Mammals Section 2 Summary • Monotremes share more traits with reptiles than with other mammals. Monotremes are the only living mammals that lay eggs. • The females of most marsupials have a pouch, and their young spend most of their time developing inside the pouch while they nurse and grow
Mammals Section 2 Summary, continued • Placental mammals make up nearly 95% of all mammalian species. The young of placental mammals develop inside the female’s uterus, where they are nourished by nutrients from her blood.
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