Chapter 32-2 Mammals

32-2 Diversity of Mammals Photo Credit: ©Zefa (RM)/M. Botzek/Masterfile 2

Mammals: Monotremes 3

Mammal Classification Monotremes, egg-layers Includes duck-billed platypus & spiny anteater

Monotreme: Egg Layers Mammal that reproduced by laying eggs Monotremes are found only in Austria, Tasmania, & New Guinea Only 3 species of Monotremes are alive today:

Monotremes: Duck-Billed Platypus Broad, flat tail, (like a beaver), rubbery snout (like the bill of a duck); webbed front feet for swimming, but sharp claws on its front & hind feet for digging; body covered with tick brown fur.

2 Species of Spiny Anteaters Monotremes: 2 Species of Spiny Anteaters Coarse, brown hair & its back & sides are covered with sharp spines that can erect for defensive purposes when threatened. Mouth located at the end of a long snout, it extends its long, sticky tongue to catch insects.

Monotremes Monotremes are a small group of egg-laying mammals consisting of echidnas and the platypus. Monotremes are oviparous mammals. Eggs have a thin, leathery shell. Babies hatch in a relatively undeveloped state. Echidnas have an abdominal pouch where they keep the young. Young feed on milk secreted by the mother’s mammary glands.

Mammals: Marsupials 9

Mammal Classification Marsupials, pouched mammals Includes Kangaroo, Koala, Opossum

Marsupials Marsupials include opossums, kangaroos, and koalas. Before it is a born, an embryonic marsupial receives nourishment by absorbing nutrient secretions in the uterus. Red kangaroos: mother immediately becomes pregnant after young (joey) is born (in pouch). But the embryo doesn’t begin to grow as long as the joey is in the pouch. When he leaves the pouch the embryo begins to mature and is born a month later.

Marsupials Young have a short period of development within the mothers body, followed by a second period of development inside a pouch made of skin & hair found outside the mothers body

Marsupials A marsupial is born very early in its development and completes its embryonic development while nursing within a maternal pouch called a marsupium.

Most Marsupials are found… Marsupial Mole In Australia & surrounding islands due to Pangaea Opossum originated in Mexico

Koala Tasmanian Devil

Mammals: Placental 16

Mammal Classification Placentals (90% of all Mammals) Placenta is an organ that nourishes the young while inside the uterus (womb) Gestation, period of time young develops in uterus; ensures offspring are protected from predators & environment

Placental Mammals Mammals that carry their young inside the uterus until birth Nourishment takes place inside the uterus through the placenta

Placenta The placenta also functions in passing oxygen to and removing waste from the developing embryo 95% of all mammals are placental

Eutherians: Placental Mammals Compared to marsupials, eutherians have a longer period of pregnancy. Usually larger placental mammals have longer gestations.

Eutherians: Placental Mammals Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta.

Orders of Placental Mammals Artiodactyla (hoofed, with even number of toes) Carnivora (specialized hunters)

Orders of Placental Mammals Cetacea (adapted to aquatic environment) Chiroptera (only mammal with true flight)

Orders of Placental Mammals Insectivora (includes world’s smallest mammals) Lagomorpha (includes some of the fastest runners, with 2 pairs of incisors)

Orders of Placental Mammals Perissodactyla (hoofed,with odd number of toes) Primates (superior intelligence, opposable thumbs)

Orders of Placental Mammals Proboscidea (trunk-nosed) Rodentia (largest order, gnawing incisors)

Placental Mammals In placental mammals, nutrients, oxygen, carbon dioxide, and wastes are exchanged efficiently between the embryo and mother through the placenta This is the type of animal that human beings along with just about the majority of all mammals belong to

Artiodactyls Hoofed mammals with an even number of toes on each foot are Artiodactyls Giraffes along with the rest of the Artiodactyls are grazing animals

Carnivores Meat-eating predators are Carnivores Grizzly Bears, like the one showed here, among a few other animals in this family are not completely Carnivorous. When meat is not readily available, they are able to eat plants as well

Cetaceans Dolphins and whales, like this Blue Whale, are called Cetaceans Cetaceans are carnivorous marine mammals that live and breed in the ocean coming up to the surface only to breathe

Chiropterans The only mammals capable of true flight Bats feed mainly on nectar, insects, and fruit Only three species of Bats feed on the blood of other invertebrates

insectivores Insectivores have sharp claws and pointy snouts that help them seek all the insects that they like to eat African Hedgehogs, like the one pictured here, have calm natures and make nice pets

Lagomorphs Like Rodents, Lagomorphs are herbivorous. Unlike rodents, they have two pairs of incisor teeth in the upper jaw, and strong back legs which are better adapted for leaping and hopping A great example of Lagomorphs are Rabbits

Perissodactyls Hoofed mammals with an odd number of toes are Perissodactyls Among the animals in this family are the Rhinoceros, which are very defensive herbivores who blindly charge at whoever or whatever they feel is a threat to their baby

Primates Primates have a highly developed brain and set of complex behaviors unlike any other animal on Earth Ring-Tailed Lemurs, like the one showed here belong to the Primate family as well as Human Beings

Proboscideans Mammals with trunks are Proboscideans, like this baby Elephant Many species existed at one time, but now only African and Asian Elephants remain

Rodents Capybaras are the largest type of Rodent there is Like all rodents, they have a single pair of long, curved incisor teeth in their upper and lower jaw Rodents love gnawing on wood and other tough plant material

Sirenians Sirenians are herbivorous sea mammals, just like these Manatees When Columbus first sailed to America and spotted these animals at sea, they were mistaken for mermaids

Xenarthrans Three-Banded Armadillos like the one pictured here are Xenarthians Xenarthians are herbivorous creatures with very simple teeth with no enamel or no teeth at all Three-Banded Armadillos are the only mammal that can perfectly roll itself into a ball

Biogeography of Mammals Convergent Evolution in Mammals Nine-Banded Armadillo Chinese Pangolin Similar ecological opportunities on different continents have resulted in convergent evolution among these and other mammals. Mammals that feed on ants and termites evolved not once but five times in different regions. Powerful front claws; a long, hairless snout; and a tongue covered with sticky saliva are common adaptations in these insect-eating animals. Common Echidna Giant Anteater Aardvark Copyright Pearson Prentice Hall 40

Copyright Pearson Prentice Hall 32-2 Quiz Copyright Pearson Prentice Hall 41

Copyright Pearson Prentice Hall 32-2 Most mammals are monotremes. marsupials. placental mammals. placental marsupials. Copyright Pearson Prentice Hall 42

Copyright Pearson Prentice Hall 32-2 Monotremes are the only group of mammals that lay eggs have hair. feed their young with milk. are endotherms. Copyright Pearson Prentice Hall 43

Copyright Pearson Prentice Hall 32-2 Rabbits belong to an order of mammals called the cetaceans. lagomorphs. proboscideans. chiroptera. Copyright Pearson Prentice Hall 44

Copyright Pearson Prentice Hall 32-2 Ant-eating mammals on different continents look similar to each other because they are all a result of divergent evolution. adapted to similar ecological opportunities. recently evolved from a common ancestor. evolved from an ant-eating reptile. Copyright Pearson Prentice Hall 45

Copyright Pearson Prentice Hall 32-2 What is the function of the placenta? production of milk exchange of materials between fetus and mother digestion of food protection of a young mammal after birth Copyright Pearson Prentice Hall 46