Endangered Species Conservation : Preserving Biodiversity for Future Generations Introduction The Earth is home to a remarkable tapestry of life, with millions of species coexisting in a delicate balance that sustains our planet's ecosystems. However, this intricate web of biodiversity faces an unprecedented threat: extinction. Human activities, such as habitat…
Introduction :- Zoology as a Career Zoology, the scientific study of animals and their behavior, is a captivating field that offers a plethora of exciting career opportunities for those with a passion for the natural world. Whether you are intrigued by the diverse world of insects, fascinated by the complexity…
Role of Zoology in Ecosystem Conservation and Understanding Introduction Role of Zoology in Ecosystem, the study of animals and their behavior, plays a critical role in our understanding of ecosystems and their conservation. Ecosystems are intricate webs of life where every species, from the smallest microorganisms to the largest mammals,…
INTRODUCTION TO SICKLE CELL ANEMIA Sickle Cell Anemia falls under the broader category of sickle cell disease (SCD), which encompasses a group of inherited red blood cell disorders. Hemoglobin is a protein responsible for carrying oxygen in red blood cells. In Sickle Cell Anemia, a single amino acid change in…
INTRODUCTION Turner syndrome is a genetic disorder affecting females, marked by the absence of one X chromosome in cells, leading to a range of physical and developmental traits. Common features include short stature, distinctive physical traits like webbed neck and low-set ears, and infertility due to underdeveloped ovaries. Hormone imbalances…
INTRODUCTION Klinefelter syndrome affects males due to an additional X chromosome (47,XXY). The condition originates from a random error during conception. Physical changes include increased height, reduced body hair, and enlarged breast tissue. Hormonal imbalances, stemming from lower testosterone levels, lead to fertility problems and other issues. Intelligence typically falls…
INTRODUCTION Patau’s syndrome, known as Trisomy 13, unveils the intricate world of genetic anomalies and their impact on human development. Named after Dr. Klaus Patau, the syndrome involves an extra copy of chromosome 13, disrupting the usual genetic blueprint. This disruption triggers a series of events that shape the physical…
INTRODUCTION Down syndrome causes and risk: Down syndrome also known as trisomy 21, is a genetic condition caused by the presence of an extra copy of chromosome 21. It is one of the most common genetic disorders, affecting approximately 1 in 700 babies born worldwide. This article aims to explore…
INTRODUCTION Patterns of feeding and digestion in arthropoda : Arthropoda is a phylum of invertebrate animals that includes insects, spiders, crustaceans, and other related organisms. They exhibit a diverse range of feeding strategies and digestion patterns, which are adapted to their specific lifestyles and habitats. Here are some common patterns…
INTRODUCTION Polychaeta, a diverse class of segmented marine worms, exhibit a wide range of feeding strategies. One of the most intriguing feeding modes found in polychaetes is filter feeding. Filter feeding is a specialized feeding adaptation that allows these organisms to extract food particles suspended in water. This article provides…
INTRODUCTION Nutrition in Protozoa involves various modes of feeding. Protozoa are a diverse group of single-celled eukaryotic microorganisms that play significant ecological roles and exhibit diverse nutritional strategies. They can be found in various environments, including freshwater, marine habitats, and soil. Understanding the nutritional requirements and mechanisms of nutrient acquisition…
INTRODUCTION Characteristics of Phylum Annelida is their segmented body plan. The bodies of annelids are divided into a series of repetitive segments or metameres, each containing specific organs and structures. This segmentation allows for functional specialization, flexibility, and adaptability to different environments. Whether they inhabit marine, freshwater, or terrestrial habitats,…
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 Phylum Protozoa includes a diverse group of single-celled eukaryotic organisms that belong to the kingdom Protista. They exhibit a remarkable range of characteristics and inhabit a wide variety of environments, including freshwater, marine habitats, soil, and even the bodies of other organisms. In this article, we will explore the…
INTRODUCTION Phylum Porifera, commonly known as sponges, represents one of the simplest and most primitive multicellular organisms in the animal kingdom. This phylum includes a wide variety of marine and freshwater species that exhibit diverse shapes, sizes, and colors. Sponges possess unique structural and physiological characteristics, lacking true tissues and…
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 Biodiversity is a fundamental aspect of our planet's ecosystems, representing the variety of life forms and their interactions within a given area. Measuring and evaluating biodiversity is crucial for understanding ecosystem health, identifying conservation priorities, and assessing the impacts of human activities on natural environments. Biodiversity indices are quantitative…
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 The neuroendocrine system in vertebrate is a remarkable communication network that coordinates and integrates the activities of the nervous system and the endocrine system in vertebrates. This intricate system plays a crucial role in regulating various physiological processes, including growth, reproduction, metabolism, stress response, and behavior. It involves the…
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 phenomenon of bioluminescence, the production and emission of light by living organisms, has captivated human curiosity for centuries. It is a remarkable natural spectacle found in a wide array of animal species across various ecosystems. Bioluminescent organisms have evolved fascinating mechanisms to generate light, and this ability serves…
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 Molecular analysis using Atomic Absorption Spectroscopy (AAS) has found numerous applications in biology due to its ability to detect and quantify trace amounts of metal ions in biological samples. Metal ions are essential for various biological processes such as enzyme catalysis, signal transduction, and DNA replication, and their imbalances…
INTRODUCTION Antibody generation by Hybridoma technology is a technique used to produce monoclonal antibodies, which are highly specific and homogeneous antibodies that recognize a single epitope on an antigen. The development of hybridoma technology revolutionized the field of immunology, as it allowed for the large-scale production of highly specific monoclonal…
INTRODUCTION Molecular analysis using circular dichroism spectroscopy and optical rotatory dispersion is a major helpful technique in biology. Circular Dichroism (CD) and Optical Rotatory Dispersion (ORD) are analytical techniques used to investigate the structural and functional characteristics of biological molecules such as proteins, nucleic acids, and lipids. These techniques are…
INTRODUCTION Molecular analysis using Fluorescence spectroscopy is a powerful technique used in biology to study the properties of biomolecules that exhibit fluorescence. Fluorescence is a phenomenon in which a molecule absorbs light of a particular wavelength and re-emits light at a longer wavelength. The emitted light is often of a…
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,…
INTRODUCTION Electrical properties of membranes are crucial to its function and the function of the cell as a whole. The membrane potential, which is the difference in electrical potential across the membrane, plays a critical role in a variety of cellular processes, including signaling, transport of ions and molecules, and…
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…
INTRODUCTION - RNA SPLICING Many of the RNA molecules in bacteria and virtually all RNA molecules in eukaryotes are processed to some degree after synthesis. Some of the most interesting molecular events in RNA metabolism occur during this post synthetic processing. Intriguingly, several of the enzymes that catalyze these reactions…
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 - RNA SYNTHESIS Transcription is, chemically and enzymatically, very similar to DNA replication. Both involve enzymes that synthesize a new strand of nucleic acid complementary to a DNA template strand. There are some important differences, of course; most notably, in the case of transcription, the new strand is made…
INTRODUCTION All amino acids are derived from intermediates in glycolysis, the citric acid cycle, or the pentose phosphate pathway. Nitrogen enters these biosynthetic pathways by way of glutamate and glutamine. Some pathways are simple, others are not. Ten of the amino acids are just one or several steps removed from…
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 - PROTEIN SYNTHESIS Proteins are the end products of most information pathways. A typical cell requires thousands of different proteins at any given moment. These must be synthesized in response to the cell’s current needs, transported (targeted) to their appropriate cellular locations, and degraded when no longer needed.An understanding…
INTRODUCTION - REGULATION OF ENZYME ACTION The activity of enzymes, often must be regulated so that they function at the proper time and place. The biological activity of enzyme is regulated in four principal ways:Allosteric control. Allosteric enzyme contain distinct regulatory sites and multiple functional sites. Regulation by small signal molecules…
CONCEPT OF FREE ENERGY AND THERMODYNAMICS PRINCIPLES Living cells and organisms must perform work to stay alive, to grow, and to reproduce. The ability to harness energy and to channel it into biological work is a fundamental property of all living organisms; it must have been acquired very early in…
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 Higher order chromatin structure comprises of nucleosomes and DNA which further form compact structures to fit 1-2 meter DNA into a very small nucleus. Earlier studies of chromosomes divided chromosomes divides chromosomal region into two categories : euchromatin and heterochromatin. Heterochromatin was characterized by dense staining with a variety…
INTRODUCTION The large human chromosome of humans contains 300 million base pairs. If it is in normal confirmation, it constitutes a chromosome over 10 cm in length. How can I fit all 46 chromosomes to a single nucleus? At the same time as being 10 µm in diameter, it keeps…
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.