Affinities of Dipnoi or lungfishes towards fishes and amphibians and their phylogenetic relationship and position with respect to Chordates diversification.
They are not the father of amphibians rather they are the uncle of amphibians.
They might have originated from Latimaria like ancestor.
Moreover it is now confirmed that Dipnoi, Crossopterygii and Labirynthodint amphibians are originated from the common ancestor.
ORIGIN OF CHORDATES
Animal kingdom is basically divided into two sub kingdoms:
Non-chordata- including animals without notochord.
Chordata- This comprising animals having notochord or chorda dorsalis.
Chordates were evolved sometime 500 million years ago during Cambrian period (invertebrates were also began to evolve in this period) .
Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.
It is believed that Chordates have originated from invertebrates.
It is difficult to determine from which invertebrate group the chordates were developed.
Chordate ancestors were soft bodied animals. Hence they were not preserved as Fossils.
However, early fossils of chordates have all been recovered from marine sediments and even modern protochordates are all marine forms.
Also glomerular kidneys are also found in some marine forms such as myxinoids and sharks. That makes the marine origin of chordates more believable.
Chordates evolved from some deuterostome ancestor (echinoderms, hemichordates, pogonophorans etc.) as they have similarities in embryonic development, type of coelom and larval stages.
Many theories infers origin of chordates, hemichordates and echinoderms from a common ancestor.
Affinities of Dipnoi or lungfishes towards fishes and amphibians and their phylogenetic relationship and position with respect to Chordates diversification.
They are not the father of amphibians rather they are the uncle of amphibians.
They might have originated from Latimaria like ancestor.
Moreover it is now confirmed that Dipnoi, Crossopterygii and Labirynthodint amphibians are originated from the common ancestor.
ORIGIN OF CHORDATES
Animal kingdom is basically divided into two sub kingdoms:
Non-chordata- including animals without notochord.
Chordata- This comprising animals having notochord or chorda dorsalis.
Chordates were evolved sometime 500 million years ago during Cambrian period (invertebrates were also began to evolve in this period) .
Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.
It is believed that Chordates have originated from invertebrates.
It is difficult to determine from which invertebrate group the chordates were developed.
Chordate ancestors were soft bodied animals. Hence they were not preserved as Fossils.
However, early fossils of chordates have all been recovered from marine sediments and even modern protochordates are all marine forms.
Also glomerular kidneys are also found in some marine forms such as myxinoids and sharks. That makes the marine origin of chordates more believable.
Chordates evolved from some deuterostome ancestor (echinoderms, hemichordates, pogonophorans etc.) as they have similarities in embryonic development, type of coelom and larval stages.
Many theories infers origin of chordates, hemichordates and echinoderms from a common ancestor.
Larval forms and their significance in arthropodaRekha Jalandra
This presentation is all about the larval forms being found in phylum arthropoda. It starts with the introduction of phylum arthropoda and then detailed information about the larval forms and their significance. i have included total 9 larval forms in this presentation.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
INTRODUCTION
The jaw (Upper and lower) is any opposable articulated structure at the entrance of the mouth.
It is typically used for grasping and manipulating food.
Jaw suspension means the fusion of upper jaw and lower jaw or skull for efficient biting.
There are different ways in which these attachments are attained depending upon the modifications in visceral arches in vertebrates.
In most vertebrates, the jaws are bony or cartilaginous and oppose vertically.
The vertebrate jaw is derived from the most anterior two pharyngeal arches supporting the gills, and usually bears numerous teeth.
The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the Devonian.
It is believed that the hyoid system suspends the jaw from the brain case of the skull, permitting great mobility of the jaws.
The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency.
The jaws were used in the buccal pump (observable in modern fish and amphibians) that pumps water across the gills of fish or air into the lungs in the case of amphibians.
Over evolutionary time the more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion, resulting in highly complex jaws with dozens of bones involved.
Jaw Suspension or Suspensoria:
The method by which the upper and lower jaws are suspended or attached from the chondrocranium is known as jaw suspension or suspensorium.
Amongst the visceral arches, the first (mandibular) arch consists of
= a dorsal palato pterygoquadrate bar forming the upper jaw,
= and ventral Meckel’s cartilage forms the lower jaw.
The second (hyoid) arch consists of = a dorsal hyomandibular supporting and suspending the jaws with the cranium, and a ventral hyoid.
The remaining visceral arches support the gills and are, hence, called branchial arches. Thus, splanchnocranium forms the jaws and suspends them with the chondrocranium.
looking after the eggs or young until they are independent to defend from predators is known as parental care.
Amphibians show great diversity in Parental care.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Larval forms and their significance in arthropodaRekha Jalandra
This presentation is all about the larval forms being found in phylum arthropoda. It starts with the introduction of phylum arthropoda and then detailed information about the larval forms and their significance. i have included total 9 larval forms in this presentation.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
INTRODUCTION
The jaw (Upper and lower) is any opposable articulated structure at the entrance of the mouth.
It is typically used for grasping and manipulating food.
Jaw suspension means the fusion of upper jaw and lower jaw or skull for efficient biting.
There are different ways in which these attachments are attained depending upon the modifications in visceral arches in vertebrates.
In most vertebrates, the jaws are bony or cartilaginous and oppose vertically.
The vertebrate jaw is derived from the most anterior two pharyngeal arches supporting the gills, and usually bears numerous teeth.
The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the Devonian.
It is believed that the hyoid system suspends the jaw from the brain case of the skull, permitting great mobility of the jaws.
The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency.
The jaws were used in the buccal pump (observable in modern fish and amphibians) that pumps water across the gills of fish or air into the lungs in the case of amphibians.
Over evolutionary time the more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion, resulting in highly complex jaws with dozens of bones involved.
Jaw Suspension or Suspensoria:
The method by which the upper and lower jaws are suspended or attached from the chondrocranium is known as jaw suspension or suspensorium.
Amongst the visceral arches, the first (mandibular) arch consists of
= a dorsal palato pterygoquadrate bar forming the upper jaw,
= and ventral Meckel’s cartilage forms the lower jaw.
The second (hyoid) arch consists of = a dorsal hyomandibular supporting and suspending the jaws with the cranium, and a ventral hyoid.
The remaining visceral arches support the gills and are, hence, called branchial arches. Thus, splanchnocranium forms the jaws and suspends them with the chondrocranium.
looking after the eggs or young until they are independent to defend from predators is known as parental care.
Amphibians show great diversity in Parental care.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
Cnidaria is a phylum containing over 9,000 species found only in aquatic and mostly marine environments. All cnidarians have radial symmetrical. There are two major body forms among the Cnidaria - the polyp and the medusa. Sea anemones and corals have the polyp form, while jellyfish are typical medusae.
2. DIGESTION • The process of conversion of complex food substances to simple absorbable forms is called digestion. • Digestion is carried out by our digestive system by mechanical and biochemical methods.
3. PHASES OF DIGESTION • The activities of the digestive system can be grouped under five main headings. • Ingestion :-This is the taking of food into the alimentary tract, i.e. eating and drinking. • Propulsion :-This mixes and moves the contents along the alimentary tract. • Digestion :-This consists of: • Mechanical breakdown of food by mastication(chewing). • Chemical digestion of food into small molecules by enzymes present in secretions produced by glands and accessory organs of the digestive system
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
3. introduction
• Mollusca = mollis (L.) = soft bodies.
• 1st used by Aristotle to the cuttle fish .
• Second largest phylum of animal
kingdom.
• Animal having soft bodies with in shell
and ventral muscular foot.
• Found in all possible habitat except in the
air.
• Most of them are marine.
• Dioecious or monoecious.
• Fertilization either internal or external.
• Development is either direct or indirect.
• Direct development -- no larval stage ,
indirect development– with larval stage.
4. Types of larva
• 3 types of larva are found in Mollusca.
TROCHOPHORE VELIGER GLOCHIDIUM
5. Trochophore larva
• Pear shaped.
• Measures about 0.5 mm in length.
• Circle of preoral cilia.
• Prototroch or velum divides the body into
two unequal parts.
• Upper one consist of prostomium.
• Lower part bearing mouth and anus.
• Preoral part is large and convex.
• Upper end consist of apical tuft.
• Prototroch is the swimming organ.
6. • Comprises mouth.
• Oesophagus.
• Stomach.
• Intestine (mesenteric).
• Sides of the mouth two ciliated elevations
present each consisting of a single cell.
• Lower end bearing a bunch of cilia called
“telotroch”.
• Generally planktonic and feeds on tiny
suspended particle, living or dead.
• Body divided in 3 regions -- pretrochal
-- pygidium
--growth zone.
• Pretrochal region consist of apical plate,
prototroch , the area surround the mouth.
• Pygidium consist of telotroch and the area
surrounding the anus.
• Growth zone lies between the mouth and
telotroch.
• The trochophore larva later develops into a
veliger larva
7. Veliger larva
• Preoral ciliate area.
• Velum begin to protrude on both sides as a
bilobed flap.
• Very delicate.
• Anterior end of the larva provided with eyes
and Tentacles.
• Larva has a shell.
• Velum is developed from the prototroch of
the trochophore.
Page 5
8. • Larval heart and kidney present which is
situated at the anterior end of the body
immediately behind the velum.
• Statocyst and gill-rudiments present.
• Long cilia of the velum function
Locomotion.
• suspension feeding.
• Alimentary canal is complete.
• Anus is shifted to anterior side.
• Foot usually bearing an operculum.
• During development of veliger larva
torsion occur.
9. Glochidium larva
• Glochidium larva enclosed by two valves.
• Each edge of which bears a hook.
• Shell valves cover a larval mantle.
• Bears four groups of sensory bristles.
• Rudimentary foot is present.
• Attached a long adhesive thread called
“Byssal thread”.
• Neither mouth nor anus.
• Measures from 0.1 mm to 0.5mm .
10. • Highly modified for a parasitic existence on
fish.
• They clamp on the body and other part of
the body.
• The larval mantle contains phagocytic cells
that feed on the tissue of host and obtain
nutrition for development.
• This period lasts for about 10-30 days.
• In the mean time the parasite is surrounded
by the overgrowth of skin of fish forming a
cyst.
• Some of the larger freshwater molluscans
may produce as many as 30,00,000
glochidia.
11. CONCLUSION
• Free-swimming larva are usually formed
when the adult is fixed.
• Internal parasites generally have a stage
which may be called larval stage in which
they are transferred either by active or
passive migration to a new host.
12. source
• Google
• Modern textbook of
zoology invertebrate book
by R.L. Kotpal.
• Biology of Mollusca book
by D.R. Khanna &P.R. Yadav.
• Wikipedia.
• www.biologyjunction.com/
mollusca
• ecoursesonline.iasri.res.in/m
od/resource/view.php?id=85576
• Invertebrate zoology book
by barnes,fox,ruppert.
