Whales and dolphins

Introduction: Whales and dolphins are the animals which are included under the order Cetacea of class mammalia. They come under the phylum chordata.
Habit and habitat : Whales and dolphins are found in all seas. Few of them also live in rivers and lakes. They are carnivorous and predaceous in habit. They are found to be swimming with great strength.
Structure : Body of these animals is fish -like and stream-lined. Scales are lacking. So, the body is naked. But a thick layer of fat is present below the skin in subcutaneous layer. It is also known as blubber . Nasal apertures are found on the top of the head region. Caudal fin or tail fin is expanded horizontally expanded. Their dorsal fin is fatty. They have minute external ear. But pinna are absent. Eyes are very small and are situated at the angle of the mouth. Their body size ranges from small five feet to hundred feet in length and about 150 ton in weight. Whales are the largest animals in the animal kingdom. They are even larger than the dinosaurs. These animals are descended from the land living ancestors and use to breathe air by coming to the surface frequently.

Rhinoceros unicornis

Rhinoceros unicornis is one of the huge animal. It belongs to the order perrisodactyla of class mammalia. This is the huge bodied mammal. Its distribution is in African continent as well as in the Asian continent. In Asia this animal is found in the countries like India, Nepal and Nepal. It is also found to be distributed in the south east countries like Indonesia , Sumatra etc.
Rhinoceros has the huge body with tons of weight. Its body is divisible into head, neck. trunk and tail. Head hinregion consists of special horn which is epidermal in origin. The name Rhinoceros unicornis signifies to the presence off single horn in its head region. Some rhinoceros have two horns in the head region. They are known as Rhinoceros bicornis. Rhinoceros bicornis or two horned Rhino are found to be distributed in a the African continent but not in Asian continent. But single horned Rhino is distributed in Asian continent but not in Africa.
Single horned Rhino which is distributed in Asia is found mainly in the dense forests of the tropical countries like Nepal.

Introduction of amphibian animals

Amphibian animals are those animals which live in the two different types of habitat, the aquatic habitat and the terrestrial habitat or land. These animals need the aquatic habitat at the time of breeding season. Some amphibians are more terrestrial than others. Toads are the amphibians which are more terrestrial. Other amphibians are more aquatic than other amphibians. For example frog is the amphibian which is more aquatic in habitat. There are other amphibians which have tail in their body and which swim in water y and look like the fish or like the larva of frog. Anyway amphibian animals have the important characters like :
- They have stream-lined body shape
- They have thin and moist skin which helps them in cutaneous respiration
- They also respire through the lungs when they are in the adult stage and when they need more oxygen like in breeding season and in the time of high metabolic rate.
- They have the body colour which harmonise them in the surrounding environment-

Introduction of 'Dipnoi'

Dipnoi are also called lung fishes. They have the peculiar character. They first appeared in the mid Devonian deposits, flourished in Permian and Triasic period and became rare. They are actually the  fishes having the skeleton made up of bones . They belong tot he subclass choanichthyes. Actually all the fishes use to respire with  the help of gills but the most interesting and peculiar character of  these fishes is that they have lungs by which they breathe in oxygen during respiration. The living Dipnoans are represented by three genera only. These show the discontinuous distribution. These genera are the following:
1.Protopterus from Africa, 2. Lepidosiren from South America and 3. Neoseratodus from Queensland - Australia.
Dipnoi are so known as lung fishes that they have air filled bladder like structures in their body called air bladder which act as lung. These fishes also possess gills. So, these fishes exhibit the double mode of breathing, i.e. breathing from gills and breathing from lungs or air bladder.

How animals communicate ?

Animals use different methods to communicate with one another. Dogs use to bark and show their communication to their fellow dogs. Mouse vibrates its tail so as to communicate with other mouse. Bee which are the insects use to produce a unique sound to give the signal of presence of some sweet fragrance of flowers in a particular direction. Crows and other birds produce the special sound to give the signal of communiacation with other birds.  Parrots make the sweet call as a method of communication. The communication of animals is for the purpose of giving signal to their own fellow species  and the other purpose is to give signal to the other species and to human beings also. communication of animals is usually nonverbal. Some animals use to communicate just by their body language. They use to make the fast or the slow movement of the body and some times come close to the human beings. Some animals use tom gaze at the other animals and also with human beings. Gazing at a point is also one of the form of communication which is seen usually among the cattles.

Animal behaviour

Definition: Animal behaviour can be defined as the activity of the animals in response to a particular type of environmental stimulus. Animal behaviour is mainly of the two types:
(1) The simple type of animal behaviour and
(2) The complex type of animal behaviour

Simple type of animal behaviour: Simple type of animal behaviour is that behaviour which takes place automatically and without any will. It is also of two types.
 a. Reflexes and b. Taxes
:Reflexes: Reflexes are the animal behaviour which is considered to be of the simple type. It takes place in the higher animals as well as the lower animals. Reflexes can be defined as the automatic activity which occurs without any will. It is also known as the involuntary activity of animals without any will There are different types of reflexes which are- Protective reflexive, anti gravity reflex, righting reflex and the conditioned reflex.
 The protective reflex is that in which the sudden acitivity is shown to protected the stimulated part of the body. For example, sudden withdrawl of one's hand when it touches any hot surface or hot object. In this activity a reflex arc is formed during this type of reflex. This reflex arc involves the different nervous components arranged in a cyclical  pattern. The various nervous components involved in this arc are the receptor organ, sensory neurons, spinal cord, brain, response the motor neuron and the effector organs.

What is animal adaptation?

Animals adjust themselves in their habitat by making the body structure suitable according to their environment. This adjustment of the animals in their environment is known as animal adaptation.
Types of animal adaptation:

(1) Aquatic adaptation
(2) Terrestrial adaptation
(1) Aquatic adaptation: Adjustment of animals in the aquatic habitat by modifying certain structures of their body is known as aquatic adaptation. The structures or features which help them to adjust themselves in aquatic habitat are known as the adaptational features or adaptational structures.
     Following adaptational structures or adaptational features are found int the body of aquatic animals

- Body is streamlined in shape which enable them to live in aquatic habitat
- Fins as the main locomotory organs in aquatic habitat. Fins are also of the different types. They are dorsal fins, ventral fins caudal fins. There are paired fins also which are known as the pectoral fins and the pelvic fins.
The fins help them in swimming mode of life but the caudal fin helps them in balancing the body in water and also for changing the direction while swimming.
Gills- as the respiratory organs are also the adaptational structures which help the aquatic animals to breathe in oxygen the oxygen which is dissolved in water. Such aquatic animals which have gills as the respiratory organs are perfectly adapted in aquaticc mode of life.

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Geometrical ratio of increase or theory of ove production

Charles Darwin, the British naturalist propounded his popular theory of organic evolution which is popularly known as ''Darwinism''. This theory states that there is the tendency of all the animals to reproduce and continue the race. They all tend to increase the number of their species and this increase in numbe rof their species is always in the geometrical ratio. This theory is known as the theory of over production or the theory of the geometrical ratio of increase. In this point of his theory he has given the example of the fast reproducing animal and the slow reproducing animal. In the fast reproducing animals he has given the example of paramecium. In the slow breeding animal he gave the example of the elephant. According to this theory of over production Darwin explains that paramecium reproduces by the process of binary fission in the favourable condition of the year and gives the two daughter paramecia. Paramecium reproduces four times a day by the process of binary fission. and the total number of daughter paramecia formed in one day are sixteen. Inthe same way if paramecium foes on reproducing in this way for one year and if all the off springs produced in one year survive without death then what will eb the result? The result will be that there will be no place for other animals to live in this world. The space will not be sufficient for only paramecium also.But there is the check and balance system also which is going on in nature.

Survival of animals in nature

Animals use to survive in nature in the different ways. They have to face the different environmental conditions in their life time. They are so vulnerable that they have to face the survival problem even in the different season of the year. For example, the cold- blooded animals which are also known as poikilothermic animals have the variable body temperature. They do not have the constant body temperature. Their body temperature fluctuates according to the environmental temperature. When there is rise in environmental temperature, the body temperature of the poikilothermic animals also goes up. Similarly, when the environmental temperature falls below zero during severe cold of winter, the body temperature of these cold-blooded animals also fallsbelow zero. But, the metabolic reactions of the body cells of living organisms can take place only in the suitable temperature of about 20 to 30 degree centigrade. The important physiological processes can go on only in the suitable temperature but if there is temperature imbalance inside the body cells then the metabolic activity of the body is disturbed. So, the cold -blooded animals have to face the survival problem in each winter season of the year. Most of them which can not escape the severe cold temperature of cold winter die in the winter season. But the warm-blooded animals have at least the constant body temperature all teh year round. They don't hav eto face the survival problem in each winter. It is not a big problem for them to ace the winter. But some cold blooded animals have adapted their temperature variation by means of the physiological adaptation. Many of them go under the ground to live for the whole winter so as to escape the severe cold temperature of the winter season. This is just to survive in winter.

Intraspecific competetion in animal world

It is the law of nature that there is always the different types of competition  going in nature among the living organisms including the animals of nature. There are mainly three different types of competition going on in nature. They are :
-Intra specific competition
- Inter specific competetion and
- the competetion or the struggle going on against the forces of nature.
Intra specific competition or intrspecific struggle: It is the struggle or competition going on in nature between the animals of the same species. In this type of competition, there is the struggle going on mainly for the food, for space to live in and for the mating partner.
Inters pecific struggle or inter specificcompetition: This is the struggle going on in nature mainly for the food. This type of struggle takes place between a predator and the prey. In this type of competition one animal called predator usually kills the animal which is its prey. This type of competition takes place in the form of the predator and the prey relationship.
Struggle against the forces of nature:  The third type of competition goes on in such a way that all the animals are doing struggle to survive against the forces of nature which are not under the control. For example, flood, land slide, erosion, earthquake, storms like hurricane, tornado etc are the naturAL factors which occur unexpectedly and cause the destruction of large number of the living animals.
  Only a few animals are able to survive in the natural disaster and the large number of them die in the struggle.This phenomenon is known as the ''Struggle for existence''. Struggle for existence is the important part of Darwin's theory. It is the important element of Darwinism.

What is Anjina ?

Anjina is a symptom of the coronary artery disease. Progressive narrowing of the arteries, due to formation of plaque supplies inadequate oxygen rich blood to the heart muscles,during exercise or stress. This condition is called ''Ischaemia''. When 'ischaemia' of the heart muscles occurs, ''angina'' is  the pain signal from the heart asking for more rest.
Anjina Pectoralis? Anjina pectoralis means chest pain. This pain is often not identified to the chest. It is often a referred or radiating pain in the upper body, left arm, jaw or upper back. The pain can also show symptoms like heaviness in chest or indigestion. An anjinal attack normally lasts for less than five minutes. The effects of ischaemia on the heart muscle are reversible and do not result in the death of cells. An anjinal attack can be relieved by rest and medication.
How to diagnose anjina? Diagnosis of anjina can be made on the basis of one's medical history.The relation of one's symptoms to the physical activity or emotional stress, identify the risk of factors for atherosclerosis. Also, certain laboratory tests, a resting electrocardiogram and chest x-ray are needed to help make the diagnosis of one's disease.
Medical History  The pattern of discomfort or pain along with a review of one's medical history will help the doctor to make a provisional diagnosis of anjina.
- Th epriority is given to the nature of the discomport or pain. Its location , what brings it on and what it relieves - The risk factors will be identified by the doctor . Risk factors are overweight, smoker etc.
- The family history will be assessed .