INTRODUCTION Phylum Platyhelminthes, commonly known as flatworms, is a diverse group of invertebrates that exhibit unique characteristics and adaptations. This phylum consists of various species, including parasitic and free-living flatworms. In this article, we will explore the characteristics of Phylum Platyhelminthes, their classification, adaptations, ecological roles, and provide examples of…
INTRODUCTION Phylum Cnidaria encompasses a diverse group of marine organisms, including jellyfish, corals, sea anemones, and hydroids. These organisms share several characteristic features that define the phylum. In this article, we will explore the characteristics of Phylum Cnidaria, its classification, unique adaptations, ecological significance, and provide examples of organisms within…
INTRODUCTION The lateral line system is a remarkable sensory adaptation found in most fish species, allowing them to perceive and navigate through their aquatic environments effectively. This sensory system comprises a network of mechanoreceptive organs, called neuromasts, distributed along the fish's body. Through the lateral line system, fish can detect…
INTRODUCTION Evolution is the fundamental process that has shaped the diversity of life on Earth. It occurs through two distinct but interconnected mechanisms: microevolution and macroevolution. Microevolution refers to small-scale genetic changes within populations, while macroevolution encompasses larger-scale changes leading to the emergence of new species or higher taxonomic groups.…
INTRODUCTION Respiration is a fundamental process in living organisms, providing oxygen for energy production and removing carbon dioxide as a waste product. To facilitate efficient oxygen transport, various animals have evolved specialized molecules called respiratory pigments. These pigments exhibit distinct structures and functions across different phylogenetic groups, enabling organisms to…
INTRODUCTION Coloration plays a crucial role in the lives of many animals, serving diverse purposes such as camouflage, communication, courtship, and warning signals. One remarkable mechanism that enables animals to achieve stunning color changes is the presence of specialized pigment-containing cells called chromatophores. Chromatophores possess the extraordinary ability to alter…
Introduction Osmoregulation is a critical physiological process that enables organisms to regulate the balance of water and solutes within their bodies. This essential mechanism allows animals to adapt to and survive in a wide range of environments with varying salinity levels, from freshwater habitats to highly saline marine ecosystems. Osmoregulation…
Introduction The animal kingdom is a realm of diverse creatures, each with its own unique adaptations for survival and communication. Among the myriad forms of communication, pheromones stand out as remarkable chemical signals that play a crucial role in inter- and intra-species interactions. In this article, we delve into the…
Introduction The animal kingdom is a diverse and fascinating realm, encompassing a wide array of creatures. One way to categorize animals is based on their structural characteristics, which leads to the classification of vertebrates and invertebrates. In this article, we will delve into the key differences between these two groups,…
Introduction Zoology, the scientific study of animals, offers a captivating journey into the realm of living organisms that inhabit our planet. From the tiniest microorganisms to the largest mammals, the field of zoology unravels the intricacies of animal life, their behavior, habitats, and evolutionary adaptations. In this article, we will…
INTRODUCTION Development of C. elegans begins when a fertilized egg undergoes a series of cell divisions to form a multicellular embryo. C.elegans (Caenorhabditis elegans) is a roundworm that has been extensively studied as a model organism in developmental biology. It has a relatively simple anatomy and a fully sequenced genome,…
FUNCTIONS OF ENDOPLASMIC RETICULUM The ER enables the movement of materials from one area of the cell to another, constituting the circulatory system of the cell. Desmotubule formation: Desmotubules are tubular extensions that stretch through plasmodesmata to connect the ER in two adjacent plant cells. Support – The cytoskeleton, which…
STRUCTURE OF ENDOPLASMIC RETICULUM The endoplasmic reticulum is often the biggest membrane in eukaryotic cells, forming a complex network of interconnecting membrane sacs or channels. It makes up 30 to 60 percent of a cell's entire membrane. Ribosomes may or may not be linked to the endoplasmic reticulum's outer membrane.…
Introduction and History Endoplasmic reticulum, the huge organelle, is made up of tubules and membranous sheets that extend across the entire cell and begin close to the nucleus. Many of the products made by a cell are manufactured and secreted by the endoplasmic reticulum, which also bundles them. One of…
The equation derived based on the Hardy Weinberg equilibrium concept is called the Hardy Weinberg law. In this particular equation, p is represented as the dominant allele’s frequency and q is the representation of the recessive allele’s frequency. This is explained with an example to conclude a Hardy Weinberg equation. Consider a single locus with the presence of only two alleles namely A and a.
The binomial system classifies organisms into groups at various hierarchic levels, on the basis of easily observable and shared morphological features like shape, number and position of limbs etc. in a descending order of group size. As the word binomial suggests, the name of a species is made up of two parts: one indicating the genus and indicating the species. Binomial nomenclature means “two part name” or “system of two part names”.Which name must be used in case of name conflicts How scientific literature must cite names
INTRODUCTION • Plasmodium (Malarial Parasite) belongs to the subphylum Sporozoan of the phylum Protozoa. All sporozoites are parasites. They are intracellular or extracellular parasites of both vertebrates and invertebrates. • Among sporozoans, Plasmodium is the best known and most important species that causes malaria fever. Of these, about 60 species are known among…
INTRODUCTION Environmental pollution is defined as the contamination of air, water, or food in such a manner as to cause real or potential harm to human health or well-being, or to damage or harm nonhuman nature without justification. Pollution is an undesired change in the physical, chemical, or biological properties…
INTRODUCTION Biotic factors and abiotic factors are two types of factors that have an influence on ecosystem. Biotic factors are the living factors that have an influence on ecosystem. Organisms do not exist alone in nature but in a matrix of other organisms of many species. Many species in an…
INTRODUCTION Noise pollution, or noise disturbance, is annoying or excessive noise that can affect the activity or balance of human or animal life. Most of the world's external noise sources are primarily caused by machinery, transportation systems, cars, planes and trains. External noise is summarized in the term environmental noise.…
INTRODUCTION All the living organisms of an ecosystem form a single biotic component, the community or biotic community (communities of the environment). All the organisms of a community live together, share same habitat, influence each other's life directly or indirectly and have reached a survival level within a given radiant…
INTRODUCTION Cells of immune system and the immune system protects multicellular organisms from pathogens attack.Highly adaptable, it defends the body against invaders as tiny as (~30 nm), intracellular virus that causes polio and as large as the giant parasitic kidney worm Dioctophyme renale. These invading pathogens needs to be detected…
INTRODUCTION - BIOSYNTHESIS OF NUCLEOTIDE Nucleotides have a variety of important functions in all cells. They are the precursors of DNA and RNA. They are essential carriers of chemical energy—a role primarily of ATP and to some extent GTP. They are components of the cofactors NAD, FAD, Sadenosylmethionine, and coenzyme…
INTRODUCTION - MECHANISM OF ENZYME CATALYSIS The enzymatic catalysis of reactions is essential to living systems. Under biologically relevant conditions, uncatalyzed reactions tend to be slow—most biological molecules are quite stable in the neutral-pH, mild-temperature, aqueous environment inside cells. Furthermore, many common chemical processes are unfavorable or unlikely in the…
INTRODUCTION CLASSIFICATION OF ENZYMES AND ENZYME KINETIC Enzymes are central to every biochemical process. Acting in organized sequences, they catalyze the hundreds of stepwise reactions that degrade nutrient molecules, conserve and transform chemical energy, and make biological macromolecules from simple precursors. The study of enzymes has immense practical importance. In…
INTRODUCTION ENERGY RICH BONDS, ENERGY TRANSDUCER, ISOMERISM AND RESONANCE A relevant reaction is one that makes use of an available substrate and converts it to a useful product. However, even a potentially relevant reaction may not occur. Some chemical transformations are too slow (have activation energies that are too high)…
INTRODUCTION PROTEIN SYNTHESIS REGULATION Of the 4,000 or so genes in the typical bacterial genome, or the 20,000 genes in the human genome, only a fraction are expressed in a cell at any given time. Some gene products are present in very large amounts: the elongation factors required for protein…
INTRODUCTION BIOSYNTHESIS OF FATTY ACID, CHOLESTROL AND MEMBRANE LIPID Lipids play a variety of cellular roles, some only recently recognized. They are the principal form of stored energy in most organisms and major constituents of cellular membranes. Specialized lipids serve as pigments (retinal, carotene), cofactors (vitamin K), detergents (bile salts),…
Introduction This article includes comprehensive information on the causes of extinction of wildlife and how to conserve it. Each ecosystem on land and in water contains a variety of living things. While fish, some insects, and small plants dwell in the aquatic ecosystem, cattle, plants, trees, and other living things…
INTRODUCTION Energy flow in environment is the important function in the ecosystem. The storage of the energy in the ecosystem is based on two basic laws of thermodynamics. The first law of thermodynamics states that when energy is converted from one form into another, energy is neither created nor destroyed.…
INTRODUCTION Abiotic and biotic factors or components are present in environment of an organism. The abiotic factors includes the atmosphere(air), hydrosphere (water), and lithosphere( land including soil).The abiotic factors are characterized by physical and chemical factors such as light, temperature, rainfall, pressure, pH, the content of oxygen and other gases.…
INTRODUCTION Environment and biosphere: Every living organism has its own surrounding, medium of environment to which it interacts and is adapted to it. The environment is the sum total of physical or abiotic and biotic conditions influencing the organisms. The life supporting environment of planet earth is biosphere. The biosphere…
INTRODUCTION Tumor suppressor genes and oncogenes are important regulatory genes which encode proteins regulating transitions in and out of the cell cycle and which also have a role in the gateway to terminal differentiation. Defects in tumor suppressor genes and oncogenes result in uncontrolled cell division, which leads to cancer.…
INTRODUCTION Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide with the highest prevalence in young women and men. Most sexually active individuals of both sexes will acquire a genital HPV infection at some point in life. While most HPV infections resolve spontaneously within two years, the…
Aquatic adaptations occur in those animals which live in water habitat, viz., fresh, brackish or sea water. They are called aquatic animals or hydrocoles. Based upon the phylogenetic history of the aquatic animals, following two types of hydrocoles have been recognised
INTRODUCTION Cancer, also called malignancy, is an abnormal growth of cells. Cancer is more than 100 types, including breast cancer, skin cancer, lung cancer, colon cancer, and lymphoma. Cancer cells are uncontrolled division of cells. Conversion of normal cell into cancerous cell is called transformation. And the cell is called…
The idea of adaptation maintains that organisms (animals and plants) are structurally and functionally designed for meeting the needs of life in the habitats in which they live. Thus, adaptations include adjustments by which an organism accommodates itself to its environment. These may occur by natural selection.
The aerial adaptations are concerned with the flight. The flight is a form of locomotion in the air under which the body has to be firstly prevented from falling down and secondly moved forwards, the speedier the better. Thus, aerial adaptations must include modifications in the animals body for reducing the weight of the body and also for the formation of organs capable of executing the flight.
TYPES OF TAXONOMY -Chemotaxonomy, also called chemosystematics, is to classify and identify organisms according to confirmable differences and similarities in their biochemical compositions. In a nutshell, the biological classification of plants and animals based on similarities and differences in biochemical composition.How scientific literature must cite names
A Taxonomic key is a device, which when properly constructed and used, enables a user to identify an organism.In lifesciences, an identification key is a printed or computer-aided device that aids the identification of biological entities, such as plants, animals, fossils, microorganisms, and pollen grains.How names are correctly established in the frame of bionomial nomenclature Which name must be used in case of name conflicts How scientific literature must cite names
Mode is the value of the variable which occurs most frequently in a distribution. Mode is also positional average which can be located by inspection.
Aortic Arches in Vertebrates Basic embryonic plan. In a typical vertebrates embryo, the major arterial channels include a ventral aorta, a dorsal aorta and usually 6 pairs of aortic arches connecting ventral aorta with the dorsal aorta.
The Chondrichthyes, also called elasmobranchii, comprise sharks, rays, skates, chimaeras, etc. Fishes are essentially aquatic and jaw-bearing true vertebrates. This class is specially known for their unimaginable number (about 40,000 species) and bewildering forms.
The Gnathostomata includes all vertebrates with upper and lower jaws. It comprises a wide range of animals, from fish to the various tetrapod classes, which have in turn been derived from a fish or fish-like ancestor. An entirely satisfactory classification of fishes is not easy to construct, because of the incompleteness of several parts of the fossil record, and the consequent lack of connecting links.
Viruses are very small submicroscopic biological entities which though lack plasma membrane and metabolic machinery. Viruses require some host cell that is they are obligate cellular parasites of either bacteria, plants or animals. There genetic material is can be RNA or DNA.
Crossopterygian, (subclass Crossopterygii), any member of a group of primitive, lobe-finned, bony fishes believed to have given rise to the amphibians and all other land vertebrates.
Arithmetic mean is defined as the quantity obtained by adding together all the given observations and by dividing this total by the number of items.
Mean, median and mode all three are Central Tendency or Averages. The Arithmetic mean lies under Mathematical Average and the other two Median and Mode are types of Positional Averages. A measure of central tendency is a typical value around which the figures congregate". The value of central tendency or average always lies between the minimum and maximum values.
A disease in which cells divide abnormally and destroy body tissues. Three classes of genes are responsible for the onset of cancer. First one is proto oncogene the normally promotes cell growth. After mutation proto-oncogene changes into oncogene whose products are excessively active in growth promotion.
Holocephali (Gr. Holos = entire + kephale = head), is a very small ancient group of highly specialized marine fishes. It comprises of rat-tailed fishes. They appeared first in the lower Jurassic and at present, are represented by a few marine genera only. It includes the only cartilaginous fishes having fleshy opercular covering of the gills.
With special features of their own, the Dipnoi combine characteristics in which they resemble different groups of fishes as well as Amphibia. AFFINITIES OF DIPNOI
The origin and evolution of Dipnoi remains problematic due to diverse opinions. They combine characteristics in which they resemble almost all the other groups of fishes as well as Amphibia. Fossil primitive Dipnoi (e.g. Diptems), shows geater similarity with fossil crossopterygians (e.g. Osteolepis), than do their living members.
The earliest known vertebrates to appear in fossil record were jawless primitive fishlike animals collectively known as the ostracoderms, and placed under the class Ostracodermi. They resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them, constitute a special group of jawless vertebrates, the Agnatha.
Adult cyclostomes are too specialized or too degenciative in many respect. It is probable that many adult characteristics are adaptations for parasitic mode of feeding. Some of their specialized features are SPECIALIZED AND DEGENERATED CHARACTERS OF CYCLOSTOMATES
We shall now consider the origin of the earlier chordate ancestors of vertebrates. That the chordates have originated from the invertebrates is not doubted by most zoologists now-a-days. Since the earlier chordate ancestors were all soft bodied forms, they left no fossil remains to give us clues as to origin of chordata. Therefore, the only basis for judging the origin of the group comes from the resemblances between the lower chordates (protochordates and the invertebrates).
The International Code of Zoological Nomenclature (ICZN or ICZN Code) is a widely accepted convention in zoologythat rules the formal scientific naming of organisms treated as animals. The rules principally regulate: How names are correctly established in the frame of bionomial nomenclature Which name must be used in case of name conflicts How scientific literature must cite names
Polymorphism is most apparent when it affects a visible or behavioral phenotype, but is not at all restricted to such traits. R. Lewontin and J. Hubby, in 1966, undertook the first extensive analysis of protein polymorphisms in natural population of Drosophila pseudoobscura by subjecting extracts of individual flies to get electrophoresis and observing the rates of migration of various proteins, which represented 18 gene loci.
New species form by speciation, in which an ancestral population splits into two or more genetically distinct descendant populations. Speciation involves reproductive isolation of groups within the original population and accumulation of genetic differences between the two groups.
The categorization and maintenance of species records is important for science and conservation. For identifying an individual species, typically scientists will first consider Biological Species Concept, then descent from common ancestry and genotypic and phenotypic cohesion. Species concepts are still subject to debate.
Evolution is change in the heritable characteristics of biological population over successive generation. Molecular evolution is change in the sequence of molecule of cell. Evolutionary genetics is study where how change in genes leads to change. Molecular markers have ability to detect genetic variation. TRENDS IN EVOLUTION
LARVAL FORMS OF ECHINODERMS :- Echinoderm larva is strikingly bilaterally symmetrical in marked contrast to radially symmetrical adult. It swims about by means of a ciliated band, which may be complicated by a number of short or long slender projection or arms from the body wall. Based upon the nature and position of the arms or their absence, lame of different classes of Echinodermata may distinguished.
LARVAL FORMS OF MOLLUSCA :- Molluscan life histories do not perfectly correspond with taxonomy, but in general it is true that the archaeogastropods and the bivalves begin life as a trochophore and rapidly pass on to a veliger. There are different types of molluscan larvae according to the importance of the pelegic phase and amount of planktonic food taken. G. Thorson (1950) recognised three ecological types of larvae in Mollusca.
LARVAL FORMS OF CRUSTACEA :- Crustaceans show both direct and indirect development. In direct development (e.g„ Palaemon, crayfish), the adult is attained by progressive growth and differentiation of the embryo, so that the newly hatched young resembles the parents in general structure.
LARVAL FORMS OF TREMATODA, CESTODA AND ANNELIDA :- The trematods or flukes are either external or internal parasites, the cestodes or tap worms are internal parasites. The termatoda class includes three order . The fasciola hepatica which is an example of order digenea have mainly 5 larval forms (i) miracidium (ii) sporocyst (ii) redia (iv) Cercaria (v) metacercaria.
Nervous system in mollusca has a well developed nervous system. It also bears paired ganglia, nerves and connectives. One important aspect is there that a Circumentric ring is formed by ganglia. A pair of cerebral ganglia (masses of nerve cell bodies) innervate the head, mouth, and associated sense organs. NERVOUS SYSTEM IN MOLLUSCA
NERVOUS SYSTEM IN ARTHROPODA is as advance as in Annelida. There is dorsal brain again connected with nerve ring to ventrae nerve cord. The arthropod nervous system consists of a dorsal brain and a ventral, ganglionated longitudinal nerve cord (primitively paired) from which lateral nerves extend in each segment.
The advanced nervous system in annelids is generally compare with coelenterates. The well developed nervous system can be seen here in form of a pair of cerebral ganglia (brain) and a double ventral nerve cord. This ventral nerve cord bears ganglia and lateral nerve in each segment as annelids are true segmented animals.
NERVOUS SYSTEM OF COELENTERATE AND ECHINODERM is not complex. Hydra and jelly fish possesses diffused nervous system, diffused nervous system is most primitive form of nervous system. Nerve cells are distributed beneath the outer epidermis. Brain is absent though there can be concentrated neuron present locally and ganglia are present.
Regulation of osmotic pressure of an organism body fluid is refer to as osmoregulation. It allow to maintain balance of water content, fluid content and electrolytes. Hence due to osmoregulation body neither become too dilute nor become too concentrated. Right concentration of solute and amount of water must be maintain by any aquatic [fresh or marine] and terrestrial organisms. It can be mostly achieved by excretion.
EXCRETION IN HIGHER TERRESTRIAL INVERTEBRATES :- Excretory system regulates the amount of nitrogenous material, inorganic salts and water content in the blood. Both cockroach and earthworm are terrestrial in habitat their excretion is discuss in detail.
EXCRETION IN HIGHER AQUATIC INVERTEBRATES :- Process by which nitrogenous waste produce during metabolism is removed is known as excretion. Some animals such hydra, echinoderms and other may not posses proper excretory organs the reason is quite clear that they are aquatic and it is supposed that nitrogenous material may be diffuse out of there body through their body surface.
EXCRETION IN LOWER INVERTEBRATES :- Every organism possess different mechanisms, organs and different excretory product. For example porifera and hydra can perform excretion through body surface where as platyhelminthes possess a specialised cells known as flame cells.
ORGANS AND MECHANISM OF RESPIRATION IN HIGHER INVERTEBRATES :- There are generally three common ways through which invertebrates can perform the process of respiration. These are cutaneous respiration which is mainly performed by lower invertebrates and annelids other is respiration through trachea and gills.
ORGANS AND MECHANISM OF RESPIRATION IN LOWER INVERTEBRATES :- In terms of biochemistry respiration is chemical reaction which occur in all living cell that provides energy after breakdown of glucose. Now respiration can be divided into two categories first aerobic respiration and other is anaerobic respiration.
PATTERN OF FEEDING AND DIGESTION IN HIGEHER INVERTEBRATES :- There are various mechanism for capturing and feeding over prey or food these are as follow Leeches generally feed over the fluid and soft tissue by piercing and then sucking from their host and simply absorbs the blood from the prey or host
PATTERN OF FEEDING AND DIGESTION IN LOWER INVERTEBRATES :- Every organism needs energy to perform its basic metabolic function. This energy can be obtain from food and sun. As sun is a universal source of energy but only autotrophic organism can obtain energy from sun.
The Ectoprocta are minute, sessile, colonial, unsegmented coelomate animals. Provided by the circular or cresentic lophophore, a u-shaped alimentary canal with anus opening near the mouth but outside of lophophore. Usually posses free swimming larva but without nephridia or circulatory system.
The Entoprocta or Endoprocta are group of small sessile aquatic animals. In which the body cavity is believed to be pseudocoel. They were formerly include in the phylum Bryozoa which however are true coelomate animals.
The Phoronida, brachiopod and Ectoprocta are collectively called as lophophorates coelomates because they all posses lophophore.
The word Rotifera is derived from latin meaning wheel barrier. They are commonly known as “wheel animalcules” as they are rotating wheel like structures
Hydrostatic movement occur when dominantly muscles are involved in their movement many organism show such kind of movement including Hydra, Earthworm, Leeches and Echinoderms.
LOCOMOTION IN PROTOZOA :- Moving ones body is an essential need of any organism. Some organism are sessile while other moves at very high speed. Some organisms moves very slowly such as amoeba or euglena where as other can move fastest example leopard.
The word coelom describes the body cavity that is internal space. But there can be difference in coelom true coelom will always be fluid filled lying between outer bodywall and inner digestive tube. It arises between two layers of embryonic mesoderm and consist of most of the visceral organs.
Metazoans can be define as multicellular organisms or as cellular animal or more accurately simply as animals.They are holozoic multicellular organisms.