Mammals
Mammals
 
A mammal is an animal that feeds its babies with milk when it is young. There are over 4,500  types of mammals. Many of the most popular animals we know are mammals, for example, dogs, cats, horses,  cows, but exotic animals like kangaroos, giraffes, elephants and anteaters belong to  this group, too. Humans are also mammals.
Mammals live in all regions and climates. They live on the  ground, in trees or underground. Polar bears, reindeer and seals are  mammals that live in the Arctic regions. Others, like camels or kangaroos prefer the  world’s dry areas. Seals and whales are mammals that swim in the oceans; bats are the only mammals  that can fly.
Mammals have five features that make them different from other animals:
Female  mammals  produce milk and feed their babies with it.
Only  mammals have hair or hair-like skin. All mammals have hair at least some time  in their lives.
Mammals  are warm-blooded. Their body temperature always stays the same and does not  change with the outside temperature.
Most  mammals have a larger and well-developed  brain. They are more intelligent than  other animals.
Mammals  protect their babies more than other animals. They prepare them for future life.
People have hunted mammals for ages. They ate their food and made  clothes out of their skins. Thousands of years ago wild mammals were domesticated and gave  human beings milk, wool and other products. Some mammals, like elephants and  camels are still used to transport goods. In poorer countries farmers use cows or oxen, to plough fields.
Today some mammals are hunted illegally. Whales  are killed because people want their meat and oil, elephants are killed for the ivory of their tusks.
Mammals are  often kept as pets. Among them are cats, dogs, rabbits or guinea pigs.
Mammals are useful to people in many other ways. Some help  plants grow and eat harmful insects . Others eat weeds and prevent them from spreading too far. The waste of  mammals is used as fertilizers that improve the quality of soil.
 
Types  of mammals
Mammals are divided into three groups:
Monotremes  are mammals that lay eggs, like a bird. They live in Australia and New Zealand.  The platypus belongs to this group
Marsupials  are mammals that raise their young ones in a pouch in their bodies.
Placentals  are the largest group of mammals. The babies grow inside their mothers until  they are ready to be born. Humans are placentals.
 
Mammals and their bodies
Skin and hair cover a mammal’s body. Some mammals have horns, claws and hoofs. The hair or fur of a mammal  has many functions. The colour often blends in with the world around them and  allows them to hide from their enemies. Some mammals produce needles or sharp hair that protects them  from attack. But the main function is to keep the body warm.
Mammals have glands that  produce substances that the body needs like hormones, sweat and milk.
A mammal’s skeleton is made up of three parts:
The skull contains  the brain, teeth and other organs.
The spine or  backbone enables mammals to stand or walk.
Limbs are legs and arms of a mammal, often with strong bones .
Mammals have a four-chambered heart system that pumps blood into all parts of their body. The blood brings oxygen to  muscles and tissue. The red blood cells of mammals can carry more oxygen than in  many other animals. Because mammals have a high body temperature they must burn  a lot of food.
Mammals digest food through their digestive  system. After food is eaten through  the mouth it goes down the throat into the stomach and passes through the intestines. Mammals  that eat plants have a complicated system with long intestines that help break  down food. Flesh is easier to digest so meat-eating mammals have a simpler  stomach.
Mammals breathe air through their lungs. Most of them have  noses or snouts with which they take in air. Dolphins and whales breathe  through a hole in the top of their back.
A whale blowing air out of its body - Aqqa Rosing-Asvid
Mammals and their senses
Mammals have five senses that tell them what is happening in their surroundings. Not all  senses are developed equally among mammals.
Mammals rely on smell to find food and warn them of their enemies. Many species use smell  to communicate with each other. Humans, apes and monkeys have a relatively bad  sense of smell.
Taste helps mammals identify the food that they eat. Most mammals have a good sense of hearing. Some  mammals use their hearing to detect objects in the dark. Bats, for example, use sounds to navigate and  detect tiny insects. Dolphins also use such a  system to find their way around.
While higher primates, like  humans, apes and monkeys have a highly  developed sense of sight other  mammals are nearly blind. Most of these mammals, like bats, are active at night.
Mammals have a good sense of touch. They have nerves on all  parts of their body that let them feel things. Cats and mice have whiskers with  which that they can feel themselves around in the dark.
 
What mammals eat
Herbivores  are mammals that eat plants. They have special teeth that allow them to chew food better. Examples of  herbivores are deer, cows and elephants. The giant panda is a plant eater that  only eats bamboo.
Carnivores  are mammals that eat other animals. Cats, dogs, tigers, lions, wolves belong to  this group. They are hunters that tear their prey apart with sharp teeth. They do not chew their food very much.
Omnivores are  mammals that eat plants and meat. Bears, , apes, pigs and humans are examples  of omnivores.
 
How mammals move
Most mammals live and move on the ground. They have four legs  and walk by lifting one foot at a time or by trotting.  Kangaroos hop and use their tail for balancing.
Mammals that  live in forests spend a lot of their time in trees. Monkeys can grasp tree branches with claws and can  hang on to them with their curved tail. Often mammals spend time hanging upside down in trees.
Dolphins and  whales are mammals that live and move around in water. Instead of limbs they have flippers which they use to move forward. Other animals, like the hippopotamus, only  spend some time in the water.
Bats are the  only flying mammals. Their wings are made of skin stretched over  their bones. They can fly by beating their wings up and down.
Gophers and moles are mammals that spend most of their life underground.
How mammals have babies
Mammals reproduce when a  male’s sperm gets into contact with a female egg and fertilizes it. A young mammal grows inside  the female’s body. Before this can happen mammals mate. Males and females stay  together for a certain time.
Unborn mammals live their mother’s body for different periods of time.  While hamsters are born after only 16 days, it takes elephants 650 days to give  birth. Human pregnancies last about 9 months.
Many new-born mammals, like horses and camels, can walk and run shortly  after they are born.
Marsupials give birth to babies that attach themselves  to their mothers. They stay in pouches because they are too weak to live alone. Almost all marsupials, including kangaroos,  koala bears or wombats live in Australia .
After birth  the glands of a female mammals produce milk. Some mammals nurse their  babies for only a few weeks. Others, for example elephants, give milk to their  babies for a few years.
The duck-billed platypus and echidnas are the  only mammals that lay eggs. After the young hatch they  drink milk from their mother, just like other mammals do.
 
Life habits
Many mammals live in families or groups. Wolves and lions help each  other in their search for food and protect each other from attackers.
Leopards, cats, tigers and other mammals prefer living  alone . They do not share their living space and food that they have, however males and  females get together to mate.
Mammals can mark the areas that they live in. They defend these  areas by fighting off attackers. Some mammals claim territories only  during the breeding season.
Many mammals migrate during special times of the year in order to get food and survive. North  American bats travel to the south because insects become scarce during  the cold winter months. Zebras and other wild animals follow the rainy seasons  in Africa to find green grass. Whales migrate to warmer southern waters off the coast of Mexico to give birth to babies because they could not survive in the  cold waters of the Arctic Ocean.
Some mammals hibernate because  they cannot find enough food to survive. Their body temperature falls, heartbeat and breathing become  slower. During this period hibernating mammals do not eat. They live from the  fat of their bodies. Bats, squirrels and other rodents hibernate.
Mammals defend themselves  from attackers in many ways. Hoofed  mammals can run quickly in order to get  food or escape. Squirrels rush into trees to hide. Some animals have special features that protect them from  enemies. Skunks spray a bad smelling liquid to keep off attackers. The fur of mammals sometimes changes  with its surroundings. Arctic  foxes, for example, are brown in summer and in the winter their coats turn white.
Squirrel eating a peanut by DAVID ILIFF
History  of mammals
The first mammals probably evolved from reptiles about 200 million years ago during the Mesozoic period .  They were rather small in a time when dinosaurs ruled the  lands. When the dinosaurs died out about 65 million years ago mammals became  the dominant land animals. Many mammals became extinct during  the Ice Age , which ended thousands of years ago.
Today, some species are in constant danger of  becoming extinct because they are hunted by humans. Hunters and poachers earn  money by selling fur, tusks and other parts of mammals. Larger wild animals are often  brought to zoos where they are protected.
 
ages = a very long time
anteater = an animal that has a very long nose and eats  insects
attach = connect
bamboo = tall tropical plant with hollow stems
beat = hit, move
blend in = to have the same colour as
brain = organ inside your head that controls the way  you feel, think and move
branch = part of a tree that grows out from the main  stem; it has leaves and fruits on it
breathing = take in air
breeding season = time during which animals mate in  order to have babies
certain = special
chew = to bite food many times before you swallow  it
claim = show that something belongs to them
claw = sharp curved nail on an animal
coast = where land meets the sea
communicate = get into contact with
constant = always
deer = a large wild animal that can run very fast,  eats grass and has horns
defend = guard, protect
digest = to change food that you have eaten into  substances that the body can use
digestive system = the way food passes through your  body
domesticate = to train an animal so that it can  work for other people or be a pet
dominant = number one
duck-billed = with a mouth like a duck
echidna = anteater
enemy = person or animal that hates you and wants to  fight against you
equally = the same
escape = to get away from a dangerous situation
evolve = grow, develop
feed = to give food to
female =about a woman
fertilize = to make a new plant or animal  grow
fertilizer = substance that is put on the soil  to make plants grow
flesh = meat
flipper = flat part of the body of some sea animals  that is used for swimming
four chambered = with four separate parts
fur = thick soft hair that covers the bodies of  animals
future = coming
gland = organ of the body that produces material  that the body needs, like hormones, sweat or milk
goods = products
gopher = north and Central American animal like  a large rat that lives in holes in the ground
grasp = get hold of
guinea pig = small furry animal with short  ears and no tail; it is often kept as a pet
harmful = dangerous
hatch = the egg breaks and a young animal comes out
hibernate = to sleep the whole winter
highly-developed = very good
hippopotamus = large grey African animal with a  big head and mouth that lives near the water
hoof = hard foot of a cow, horse or a camel
hop = jump
hormone = chemical substance that the body produces  and influences how you grow and develop
however = but
human = a person
Ice Age = one of the long periods of time thousands of  years ago when ice covered the northern countries
identify = recognise, find
instead of = in something’s place
intestine = long tube through which food  passes after it leaves your stomach
ivory = the hard smooth yellow material from the  tusks of elephants
limb = leg or arm
mark = show the position of something
marsupial = animal that carries its baby in  pocket of skin
mate = to have sex in order to produce babies
Mesozoic = the geologic middle ages
migrate = to travel regularly to another place in the  world
mole = small dark furry animal that is almost blind  ; moles usually live under the ground
navigate = travel around, steer
oxygen = gas that has no colour or smell and which we  need to breathe
platypus = a small furry animal that has a mouth and  feet like a duck
plough =  turn  over the earth so that seeds can be planted
poacher = someone who catches or shoots animals  illegally
popular = well-known
pregnancy = when a female has a baby growing  inside her
prepare = to get ready
prey = victim, target, the animal they want to eat
primate = a member of a group of animals that include  humans and monkey
protect = defend against enemies
reindeer= a large deer with long horns that lives in  northern, colder areas
rely = depend on, need
reproduce = to have babies
reptile = animal like a snake or lizard whose body  temperature changes according to the temperature around it
rodent = small animal that has long sharp front teeth  , like a rat
rule = to have the power over others
rush = hurry
seal = a large sea animal that eats fish and lives  around the coast
search = look for
sense = one of the five natural powers : seeing,  hearing, feeling, tasting, smelling
sense of  hearing = the way an animal can hear
share = use with another animal
sight = vision, ability to see
skull = bones of a person’s or animal’s head
skunk = a black and white North American animal that  produces a strong bad smell when it is attacked
snout = long nose of an animal
soil = the top layer of the earth, on which plants  grow
species = group of plants or animals that are alike  and can produce young ones
sperm = a cell of a man that can produce new life
spine = the row of bones down the centre of your  back
spray = a stream of very small drops
spread  = to  move from one place to another
squirrel  = small  animal with furry skin that climbs trees and eats nuts
stretch = to go from one place to another
surroundings = the world around us
survive = continue to live
sweat = drops of salty liquid come through your skin  because it is hot or you are doing a lot of exercise
tail = part that sticks out of the back of an  animal
tear = rip
throat = the passage from your mouth to the tubes  that go to your stomach
tiny = very small
tissue = the material that forms cells
trot = to move quickly with each front leg moving at the same time as one of the  back legs
tusk = long curved tooth of an elephant
upside  down = with the top at the bottom and the bottom at the top
warm-blooded = animals that have the same body temperature all the time
waste = the material that animals leave after they digest food
weak = not strong