Mammals

ClassificationKingdom: Animalia

Phylum: ChordataSubphylum: Vertebrata

Class: MammaliaSubclasses: Marsupials, Monotremes,

Placentas

*There are about 5,000 species They evolved from small ones like shrews during the dino era.

Origin of Mammals

• 65 mya dinosaurs became extinct opening up habitats for new species of mammals

Characteristics• Mammals are vertebrates, which means they have backbones.

All mammals have hair at some time of their life. In whales, the hair is present before birth only.

• Mammals are warm-blooded endotherms, which means that their body temperature stays about the same, no matter how hot or cold their surroundings are.

• Mammals' hearts have four chambers, for the blood to move through. They have larger brains than other animals.

• Mammals give birth to live young. They are the only animals that feed their young with milk that the mother produces in modified sweat glands that are called mammary glands.

• They have 3 middle ear bones (the malleus, incus, and stapes).

• They also have sweat glands and oil glands.

• They are the only class with a blowhole for breathing.

• Mammals are animals that engage in play and show emotion.

• They care for their young.

Dugong

 

Teeth• Mammalian teeth

1. Molars (cheek teeth): for crushing and grinding food

2. Premolars: crushing, grinding, shearing food

3. Canines: piercing points for cutting and capturing prey. (largest in carnivores)

4. Incisors: flat chisels or cones used to clip or cut food

– Mammals have different kinds of teeth to match their diets• Carnivores: meat eaters, have canine teeth• Herbivores: plant eaters, have premolars

and molars• Omnivores: eat meat and plants, have all 4

types

I think they are here to learnabout the Marsupials.

Who are these people?

Marsupials!!

MARSUPIALSMarsupials (Megatheria) are pouched mammals

whose babies are born in a very undeveloped state; the young then attach themselves to their mother's nipple. Many marsupials have a pouch that encloses the young.

The biggest marsupial is the human-sized red kangaroo (Macropus rufus); the smallest marsupial, the pilbara (Ningaui timealeyi), would fit in a person's hand. Some commonly-known marsupials include the kangaroo, opossum, Tasmanian devil, and koala. The only marsupial in North America is the Virginia opossum.

Marsupials evolved during the late Cretaceous period, about 100 to 75 million years ago, during the time of the dinosaurs.

The koala is an Australian marsupial. It

is not a bear.

Sugar glider is a small marsupial (also known as the lesser flying phalanger) glides from tree to tree in Australia and nearby islands.

Tasmanian Devils are nocturnal, meat-eating marsupials from Tasmania.

The Tasmanian Tiger was a large, meat-eating marsupial from Tasmania, mainland Australia, and New Guinea. It is probably extinct.

Virginia Opposum is the only marsupial from North America.

Tasmanian Devil

Virginia Opposum

Bandicoots are marsupials with pointy snouts.

Kangaroos hop and have pouches. Their babies are called joeys.

Wallabies are small to

medium-sized kangaroos.

The wombat is a rare, burrowing marsupial from mainland Australia and Tasmania.

Long Nosed Bandicoot

Red Necked Wallaby

monotremeThey are mammals that lay eggs. There are

only two monotremes: the platypus and the echidna. The females usually lay two eggs at a time. The eggs have a leathery skin, like reptile eggs. After the eggs have hatched, the young are fed mother's milk. However, the females do not have nipples, and the young lick milk that oozes from the skin of the mother's abdomen .

These people are still staring at us.I think

they arehere to learn

aboutPlacentals.

Placentals

Placental mammals are characterized by the following:

Placental mammals nourish their young within the mother's uterus by the placenta that is a composite of maternal and fetal tissue.

• The placenta is the organ of exchange of nutrients and wastes between the maternal blood and the fetal blood. Placental nourishment is more efficient than nourishment of pouched animals. Placental mammals develop more quickly than marsupials. Representatives of this group are found in virtually every aquatic and terrestrial environment.

• Placental mammals are separated into large groups based on their characteristics and adaptations. Some examples are listed below:

• Milk-secreting glands nourish the young from nipples.

• Brain capacity is increased, allowing more capacity for memory, learning, and conscious thought.

• Teeth (incisors, canines, premolars, and molars) are extensive and specialized to meet dietary habits.

* Carnivora- are carnivores (flesh eaters), they have teeth adapted for tearing flesh, clawed toes and well-developed brains. Common animals in this group include dogs, cats, bears, seals and otters.

• * Cetacea- are mammals that are adapted for life in the ocean. Whales and dolphins belong to this order.

• * Chiroptera- are mammals that fly. They are mostly nocturnal. Bats belong to this order.

• * Insectivora- are mammals that eat insects. They typically have long skulls, narrow snouts, and clawed feet. Common animals in this order are shrews, hedgehogs and moles.

• * Lagomorpha- have long rear limbs adapted for jumping. They include rabbits and hares.

* Perissodactyla- are mammals that have hooves, are herbivores (plant eaters) and have an odd number of toes on each foot. Horses, zebra and rhinoceroses belong to this order.

• * Artiodactyla- are herbivores that have hooves with an even number of toes. Sheep, goats, pigs, giraffes and deer belong to this order.

• * Primates- are mammals that have thumbs used for grasping. They are omnivores (eat both plants and animals). Monkeys, apes and humans belong to this order.

• * Proboscidea- are mammals with long muscular trunks and extra long teeth called tusks. Elephants belong to this order.

• Rodentia- have teeth adapted for gnawing and are relatively small. This order includes the largest number of mammals including rats, mice, porcupines, gophers and squirrels.

• *Sirenia- Fully Aquatic, herbivorous mammals that inhabit rivers, estuaries and coastal marine waters, swamps, and marine wetlands. It includes manatees, sea cows and dugongs.

• * Xenrthra- its teeth, instead of having a root, have a number of thin tubes of dentine. The teeth have no enamel coating and are worn away and re-grow continuously. They include aardvarks, sloths, armadillos, and anteaters.

Importance of Mammals

• Environmental Impact– Control populations– Pollinate flowers– Control insects– Disperse seeds

• Displacement– Millions of wildlife habitats are being

destroyed to build shopping centers, houses, etc.

Body Systems• Circulatory System

– Endotherms have a nearly constant internal body temperature

– 4 chambered hearts– Lungs are covered with millions of

microscopic sacs• Increases the surface area of the lungs = greater

exchange of O2 and CO2

• Digestive System– Like teeth, the digestive system is specialized

based upon the food the mammal eats– Herbivores have longer digestive tracks than

carnivores in order to digest hard to break down plants

– Ruminants are hoofed mammals with multi-chambered stomachs

• Cows have 4, Camels have 3

• Food goes into the mouth, is broken down by the teeth and saliva.

• Food travels down the esophagus and into the stomach.

• The liver produces bile that is stored in the gall bladder.

• The pancreas travels the bile to the stomach for digestion.

• The food then passes into the small and then large intestine and out the anus.

• Liquid waste goes to the kidney, to the bladder and out the ureter.

• Nervous System– Made up of the brain, spinal cord, and nerves– In mammals the cerebral cortex is larger than

in other animals• This part of the brain is responsible for learning,

problem solving, and remembering

– The part of the brain responsible for muscle coordination is also larger

Respiratory System

• All mammals breathe air through lungs.• The air travels in the nostrils and down the

wind pipe or trachea.• The bottom of the trachea branches off to

each lung via the bronchial tubes.• The lungs are covered with a lining called

the pleura.• The diaphragm helps push the air up and

out of the lungs.

• Reproductive System– Internal fertilization– Most mammals give birth to live young after a

period of gestation• Gestation: period of development in the uterus

from conception until birth• Gestation period varies by species

– The human gestation period is 9 months

– Some young are born helpless, others are born more fully developed

• Ex. Baby mice are born blind, baby elephants can travel with their parents a few minutes after birth

– In most species the females raise the young, but in others the males help in this process

• Mammals are warm-blooded, which means that their body temperature stays about the same, no matter how hot or cold their surroundings are.

• Mammals' hearts have four sections, called chambers, for the blood to move through. They have larger brains than other animals.

• Mammals give birth to live young. They are the only animals that feed their young with milk from the mother's body. In most mammals, the females have a placenta which feeds the young as they develop inside the mother's uterus, or womb before they are born. Some examples of this kind of mammal are dogs, whales and dolphins, giraffes and... humans!

• One group of mammals is called marsupial.• Like other mammals, marsupials give birth to live young, but they give birth to young that are still

very tiny and unformed. After the young are born, they climb up their mother's belly and into a pouch, which is like a pocket in the female's body. Inside the pouch, the young attaches itself to a teat and remains there for some time, depending on which kind of animal it is. Milk is fed to the baby through the teat. Any ma rsupial baby is called a joey.

• Probably the best known marsupials are the koala, kangaroo and possum.• A very small number of marsupials, such as the numbat and the red-tailed phascogale, do not

have a pouch.• Most of the world's marsupials are native to Australia, and many of them are endangered.• Another group of mammals is called monotreme. • They are mammals that lay eggs.There are only two monotremes: the platypus and the echidna.

The females usually lay two eggs at a time. The eggs have a leathery skin, like reptile eggs. After the eggs have hatched, the young are fed mother's milk. However, the females do not have teats, and the young lick milk that oozes from the skin of the mother's abdomen .