Monday, 28 November 2011

Invertebrate



Animals that lack backbone are called as invertebrates. These invertebrates are seen in all places from deserts to forests and from caves to seabed and even in unbearable Polar Regions. They can also been seen in the air.
And most of the invertebrates are small in their size and only few reach the impressive sizes. For example the heaviest invertebrate is the giant squid and the longest one is the ribbon worms and the smallest one is the rotifers. 
Ribbon Worms


 
Rotifers

Other animals that are considered as invertebrates are spiders, worms, snails, centipedes, clams, jellyfish, crabs and squid.
All the species that belong to invertebrates have their own life cycle. All invertebrates lay eggs and the eggs of some species directly hatch into an adult and some enter into the larvae stage and then move into an adult.


Since the invertebrates are many in number they all share a single characteristic in common.
The first and common characteristic of all the invertebrates is that they all lack backbone
These soft bodied animals maintain their body shape by maintaining their internal pressure. Some invertebrates have hard outer covering called as exoskeleton to protect them from their predators.


The exoskeleton not only prevent the animals from their enemies they also provide a support to their muscles and in the land they prevent the water content from evaporating so that the animal species does not dry up.The body of the invertebrates is of two types. They are radial symmetry and the other one is called as bilateral symmetry.

Bilateral symmetry


 
Radial Symmetry

Invertebrates have simple nervous system. The internal anatomy of the invertebrates differs from each other. Some may have respiratory, excretory and circulatory organs and in some species these organs may be absent. 

With 2 million known animal species on earth nearly 95% of the animals are invertebrates. 
These invertebrates can be found in all the environments from hot desserts to unbearable polar zones. These vertebrates are seen in different shapes, sizes and colours.


Friday, 25 November 2011

Amphibians





The amphibians belong to the class amphibian. Ectothermoc or cold blooded animals like frogstoadssalamandersnewts, and caecilians metamorphose from a juvenile, water breathing form to an adult, air breathing form. Amphibians are four limbed animals. As by their ancestors "the fish" the amphibians lay eggs in the water. Amphibians are similar to the reptiles. Amphibians are cold blooded animals that posses backbone and are the direct offspring of fishes. They have the capacity to live both on land as well as in water.
Salamander

Frog


Amphibians have complex circulatory system unlike fish that have scales. The larvae of the amphibians that develop in the water breathe through gills while the adults breathe through skins and lungs. Some amphibians are terrestrial at some point of time in their life cycle.
The word amphibian means two-lives.  Amphibians spend their lives in the water and on land.

Tadpole

All amphibians begin their life in water with gills and tails. As they grow, they develop lungs and legs for their life on land. 
Toad

Amphibians are cold-blooded, which means that they are the same temperature as the air or water around them. 
Caecilian
Salamander
 
Caecilian
 
Frog

There are more than 4,000 different kinds of amphibians. Members of this animal class are frogs, toads, salamanders, newts, and caecilians or blindworms.



Thursday, 24 November 2011

FISH



Fish are a class of aquatic vertebrates.  The combination of gills, fins and the fact that they live only in the water make fish different from all other animals.

Fish spend all of their lives in the water and are cold-blooded with the exception of Tuna family and the Mackerel shark family.

Tuna Fish
Mackerel Shark

Scientists believe that there are more than 24,000 different species of fish in the world.
 

They range in size from the largest, Whale shark at 16 m (51 ft) long, to the smallest the 8 mm (1/4 in.) Stout Infantfish.

Stout Infantfish

Whale shark

Most fish have a skeleton made of bone but some, like sharks, have a skeleton made of cartilage.



Many people mistakenly group whales and dolphins into the fish family. They are actually mammals.  They are warm-blooded, feed their babies with milk from their bodies and breathe air into lungs.

Jellyfish and starfish are not fish at all!  They are marine invertebrates.








Wednesday, 23 November 2011

Reptile


Reptile



Animals that have scales and the ability to creep are called Reptiles. Since the animals have the ability to creep they got the name Reptiles 


Reptiles are cold blooded animals that live on the world since the Dinosaurs period. The Dinosaurs is the biggest and the extinct species of the reptiles.

Today about 6500 species of reptiles survive in the world. Those include crocodiles, snakes, lizards and turtles. 

Reptiles are covered with scales to protect themselves. Reptiles are capable of living on both land and in water. The body structure of the reptiles is designed to make them adapt to survive both on land and in water. 

The feet of the reptiles have claws in their toes and the body is covered with scaly skins.

So what makes a reptile a reptile? 

The two biggest clues are:
   1) they are cold-blooded, and
   2) they are covered in scales.

Reptiles are cold blooded animals. They regulate their body temperature by adapting to the outside temperatures. To keep them warm they stay in the sun and to keep them cold they stay in the water or hide under the ground or rock. Reptiles are air breathing animals and give birth to the young one by laying eggs. Usually reptiles breathe through lungs but sometimes they can suck up oxygen in the water through the membranes present in the mouth. Being cold-blooded means that their bodies react to the temperature of their surroundings. When they get too warm, they can go into the water or shade to cool off. 

When they get too cold they can hang out in the sun to warm themselves up.
Some creatures that belong to the reptile group of animals are snakes, alligators, crocodiles, tortoises, lizards, etc.
Scales protect their bodies.
Scales can be hard or soft, large or small.

Reptiles are born on land and are born with strong instincts, so they are on their own at birth.  Just think, no parents to nag them about cleaning their rooms!

Monday, 21 November 2011

Mammals



Mammals are one of the 6 main classes of animals.  Animal classes are groups of animals that scientists consider to be alike in some important ways.  Mammals are the animal class that people belong to.  


There are only about 4,000 kinds of mammals.  This sounds like a lot, but when you consider there are 21,000 kinds of fish and a whopping 800,000 kinds of insects you’ll realize mammals are a pretty small class!

Here are some of the ways that mammals are alike!

Mammals are warm blooded.
but mammals’ bodies are built to maintain just about the same temperature all the time.  Warm blood lets the mammals be very active and live in a wide variety of places.  
Mammals are everywhere.  Polar bears live in very cold areas.  Camels live in hot areas.  Moles live under the ground.  Bats live in caves and fly in the air. Dolphins live in the oceans.  Fur and fat help protect mammals who live in the cold.  Mammals sweat or pant to release extra heat if they live somewhere toasty.


Mammal Babies:  We all drink Milk!
Most mammal babies live inside their mothers before they are born, just like humans.
When the baby is big enough, it comes out of its mother’s body.  Many people mistakenly think that being born alive is something all mammals have in common.  There are, however, a few mammals (like the duckbilled platypus) who lay eggs like a bird!


Mammals aren't spineless
Mammals are vertebrates, which means that they all have backbones (spines).  Believe it or not, most animals don't have backbones -- mammals are one of the few groups that do.  
All mammals, except some sea cows and sloths have seven bones in their necks.  This includes giraffes who have VERY long spines!  Their necks can be 6 1/2 feet long, but they're still made up of just seven bones.



Tetrapods
All mammals have four limbs. Some mammals walk on all four limbs, others walk on two and others can do both.


Hair
Mammals have hair which grows from follicles found in the skin. Functions of the hair include warmth, protection and to act as a sensor.


Respiration
Mammals breathe using a pair of lungs composed of spongy like material. The breathing rate of mammals varies - a whale might only breathe once every two hours while smaller rodents breathe 150+ times a minute.


Reproduction
Most mammals give birth to live young but a few lay eggs.
E.g. Platypus lay eggs.
Platypus lay eggs.


Cat gives birth.



Let us see what is mammals together!



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