In this presentation, Phylum Mollusca Is described. After watching this you will learn Evolutionary Perspective of Mollusca and Relationships to Other Animals, Molluscan Characteristics, Class Gastropoda, Torsion, Shell Coiling, Locomotion, Feeding and Digestion, Other Maintenance Functions, Reproduction and Development, Gastropod Diversity, Class Bivalvia, Shell and Associated Structures Gas Exchange, Filter Feeding, and Digestion, Other Maintenance Functions Reproduction and Development, Bivalve Diversity, Class Cephalopoda, Shell, Locomotion, Feeding and Digestion, Other Maintenance Functions, Learning, Reproduction and Development, Class Polyplacophora, Class Scaphopoda, Class Monoplacophora, Class Solenogastres, Class Caudofoveata, Further Phylogenetic Considerations. It is part of BS Zoology Course, Animal diversity.
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.
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.
Reptiles are a group (Reptilia) of tetrapod animals comprising today's turtles, ... The reptiles were, from the outset of classification, grouped with the amphibians. ... between lizards, birds, and their relatives on the one hand (Sauropsida)
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.
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.
Fish has a air bladder system ,its a sac containing gas especially air .it provide buoyancy to the fish and help them to stay and swim in water current swimming. It include air bladder and its function and also focus to weberian ossicles and its function.
Introduction
Gnathostomata are the jawed vertebrates. (gnathos= "jaw" + (stoma)="mouth".
It comprises roughly 60,000 species. (99% of all living vertebrates).
Living gnathostomes have teeth, and paired appendages.
A horizontal semicircular canal is present in the inner ear.
Myelin sheaths is present on the neurons.
Adaptive immune system uses V(D) J recombination ( it is the mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. VDJ recombination is the process by which T cells and B cells randomly assemble different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to generate unique receptors (known as antigen receptors) that can collectively recognize many different types of molecule. While Agnatha (petromyzon and hagfish) use genetic recombination in the variable lymphocyte receptor gene.
It is now assumed that Gnathostomata evolved from ancestors that already possessed a pair of both pectoral and pelvic fins.
In addition to this, some placoderms were shown to have a third pair of paired appendages, that had been modified to claspers in males and basal plates in females—a pattern not seen in any other vertebrate group.
It is believed that the jaws evolved from anterior gill support arches that had acquired a new role, being modified to pump water over the gills by opening and closing the mouth more effectively – the buccal pump mechanism.
Presence of Calcified, bony skull and vertebra are the characteristic features of Gnathostomata (fishes, amphibians, reptiles, birds and mammals).
Pelvic fins are situated just in front of the anus.
Interventrals and basiventrals present in the backbone. These are the elements of the backbone which lie under the notochord, and match the basidorsals and interdorsals respectively.
Gill arches which lie internally to the gills and branchial blood vessels, contrary to the gill arches of all jawless craniates, which are external to the gills and blood vessels.
A horizontal semicircular canal in the inner ear.
Paired nasal sacs which are independent from the hypophysial tube.
There are numerous other characteristics of the soft anatomy and physiology (e.g. myelinated nerve fibres, sperms passing through urinary ducts, etc.), which are unique to the gnathostomes among extant craniates, but cannot by observed in fossils.
Reptiles are a group (Reptilia) of tetrapod animals comprising today's turtles, ... The reptiles were, from the outset of classification, grouped with the amphibians. ... between lizards, birds, and their relatives on the one hand (Sauropsida)
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.
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.
Fish has a air bladder system ,its a sac containing gas especially air .it provide buoyancy to the fish and help them to stay and swim in water current swimming. It include air bladder and its function and also focus to weberian ossicles and its function.
Introduction
Gnathostomata are the jawed vertebrates. (gnathos= "jaw" + (stoma)="mouth".
It comprises roughly 60,000 species. (99% of all living vertebrates).
Living gnathostomes have teeth, and paired appendages.
A horizontal semicircular canal is present in the inner ear.
Myelin sheaths is present on the neurons.
Adaptive immune system uses V(D) J recombination ( it is the mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. VDJ recombination is the process by which T cells and B cells randomly assemble different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to generate unique receptors (known as antigen receptors) that can collectively recognize many different types of molecule. While Agnatha (petromyzon and hagfish) use genetic recombination in the variable lymphocyte receptor gene.
It is now assumed that Gnathostomata evolved from ancestors that already possessed a pair of both pectoral and pelvic fins.
In addition to this, some placoderms were shown to have a third pair of paired appendages, that had been modified to claspers in males and basal plates in females—a pattern not seen in any other vertebrate group.
It is believed that the jaws evolved from anterior gill support arches that had acquired a new role, being modified to pump water over the gills by opening and closing the mouth more effectively – the buccal pump mechanism.
Presence of Calcified, bony skull and vertebra are the characteristic features of Gnathostomata (fishes, amphibians, reptiles, birds and mammals).
Pelvic fins are situated just in front of the anus.
Interventrals and basiventrals present in the backbone. These are the elements of the backbone which lie under the notochord, and match the basidorsals and interdorsals respectively.
Gill arches which lie internally to the gills and branchial blood vessels, contrary to the gill arches of all jawless craniates, which are external to the gills and blood vessels.
A horizontal semicircular canal in the inner ear.
Paired nasal sacs which are independent from the hypophysial tube.
There are numerous other characteristics of the soft anatomy and physiology (e.g. myelinated nerve fibres, sperms passing through urinary ducts, etc.), which are unique to the gnathostomes among extant craniates, but cannot by observed in fossils.
Phylum Mollusca, Class Gastropoda, Torsion, Locomotion, Digestion,Reproductio...Dr. Muhammad Moosa
In this presentation, Phylum Mollusca Is described. After watching this you will learn Evolutionary Perspective of Mollusca and Relationships to Other Animals, Molluscan Characteristics, Class Gastropoda, Torsion, Shell Coiling, Locomotion, Feeding and Digestion, Other Maintenance Functions, Reproduction and Development, Gastropod Diversity, Class Bivalvia, Shell and Associated Structures Gas Exchange, Filter Feeding, and Digestion, Other Maintenance Functions Reproduction and Development, Bivalve Diversity, Class Cephalopoda, Shell, Locomotion, Feeding and Digestion, Other Maintenance Functions, Learning, Reproduction and Development, Class Polyplacophora, Class Scaphopoda, Class Monoplacophora, Class Solenogastres, Class Caudofoveata, Further Phylogenetic Considerations. It is part of BS Zoology Course, Animal diversity.
Lecture on arthropods and echinoderms.pptEsayDawit
zoologist now what are arthropods, what are the distinguishing features and what are echinoderms with identifying their features from the rest other invertebrates.
Phylum Mollusca, Class Polyplacophora, Class Monoplacophora, Phylogenetic con...Dr. Muhammad Moosa
In this presentation, Phylum Mollusca Is described. After watching this you will learn Evolutionary Perspective of Mollusca and Relationships to Other Animals, Molluscan Characteristics, Class Gastropoda, Torsion, Shell Coiling, Locomotion, Feeding and Digestion, Other Maintenance Functions, Reproduction and Development, Gastropod Diversity, Class Bivalvia, Shell and Associated Structures Gas Exchange, Filter Feeding, and Digestion, Other Maintenance Functions Reproduction and Development, Bivalve Diversity, Class Cephalopoda, Shell, Locomotion, Feeding and Digestion, Other Maintenance Functions, Learning, Reproduction and Development, Class Polyplacophora, Class Scaphopoda, Class Monoplacophora, Class Solenogastres, Class Caudofoveata, Further Phylogenetic Considerations. It is part of BS Zoology Course, Animal diversity.
Phylum Mollusca, Class Bivalvia, Shell, Locomotion, Digestion,Reproduction an...Dr. Muhammad Moosa
In this presentation, Phylum Mollusca Is described. After watching this you will learn Evolutionary Perspective of Mollusca and Relationships to Other Animals, Molluscan Characteristics, Class Gastropoda, Torsion, Shell Coiling, Locomotion, Feeding and Digestion, Other Maintenance Functions, Reproduction and Development, Gastropod Diversity, Class Bivalvia, Shell and Associated Structures Gas Exchange, Filter Feeding, and Digestion, Other Maintenance Functions Reproduction and Development, Bivalve Diversity, Class Cephalopoda, Shell, Locomotion, Feeding and Digestion, Other Maintenance Functions, Learning, Reproduction and Development, Class Polyplacophora, Class Scaphopoda, Class Monoplacophora, Class Solenogastres, Class Caudofoveata, Further Phylogenetic Considerations. It is part of BS Zoology Course, Animal diversity
Phylum Mollusca, Characteristics and Classification.pptxDr. Muhammad Moosa
In this presentation, Phylum Mollusca Is described. After watching this you will learn Evolutionary Perspective of Mollusca and Relationships to Other Animals, Molluscan Characteristics, Class Gastropoda, Torsion, Shell Coiling, Locomotion, Feeding and Digestion, Other Maintenance Functions, Reproduction and Development, Gastropod Diversity, Class Bivalvia, Shell and Associated Structures Gas Exchange, Filter Feeding, and Digestion, Other Maintenance Functions Reproduction and Development, Bivalve Diversity, Class Cephalopoda, Shell, Locomotion, Feeding and Digestion, Other Maintenance Functions, Learning, Reproduction and Development, Class Polyplacophora, Class Scaphopoda, Class Monoplacophora, Class Solenogastres, Class Caudofoveata, Further Phylogenetic Considerations. It is part of BS Zoology Course, Animal diversity.
In this presentation, phylum Phylum Xenoturbellida is described. Phylum Onychophora known as velvet or walking worms. After watching this you will learn the characteristics and Xenoturbella bocki and Xenoturbella westbladi .The brief description of Phylum Phylum Xenoturbellida along with reproduction and fertilization also described. The concept of phylum Xenacoelomorpha. It is part of BS Zoology Course, Animal diversity.
In this presentation, phylum Phylum Chaetognatha is described. Phylum Chaetognatha known as arrow worms. After watching this you will learn the characteristics and Examples Sagitta, Spadella. The brief description of Phylum Chaetognatha along with reproduction and fertilization also described. It is part of BS Zoology Course, Animal diversity.
In this presentation, phylum Onychophora is described. Phylum Onychophora known as velvet or walking worms. After watching this you will learn the characteristics and Examples Peripatus. The brief description of Phylum Onychophora along with reproduction and fertilization also described. It is part of BS Zoology Course, Animal diversity.
In this presentation, Phylum Mesozoa is described. After watching this you will learn the characteristics and Examples Dicyema spp., Pseudicyema spp., and Dicyemennea The brief description of Phylum Mesozoa along with reproduction and fertilization also described. Its relationship with Phylum Rhombozoa and Orthonectida. It is part of BS Zoology Course, Animal diversity.
In this presentation, Phylum Phoronida, horseshoe worm is described. After watching this you will learn the characteristics and Examples Phoronis architecha, Phoronopsis, epistome, a lophophore-bearing mesosome, and an elongate trunk, metasome ectoprocts and cycliophorans. The brief description of Phylum Phoronida along with reproduction and fertilization also described. Its relationship with brachiopods as sister groups within Lophotrochozoa. It is part of the BS Zoology Course Animal diversity.
In this presentation, Phylum Entoprocta is described. fter watching this you will learn the characteristics and examples Urnatella gracilis, Pedicellina cernua, ectoprocts and cycliophorans The brief description of Phylum Entoprocta along with reproduction and fertilization. It is part of BS Zoology Course Animal diversity.
In this presentation, Phylum Cnidaria, Coelenterata is described. After watching this you will learn the characteristics of Phylum Cnidaria, Coelenterata, The Body Wall and Nematocysts, Alternation of Generations, Maintenance of Functions, Reproduction, Class Hydrozoa, Class Staurozoa, Class Scyphozoa, Class Cubozoa, Class Anthozoa, locomotion, Digestion, Nutrition,Exchanges with the Environment, Nervous and Sensory Functions, Reproduction and Development, cnidocytes, alternation of generations, polyps, medusa, dactylozooids gastrozooid, gonozoid, obelia, aurelia Jelly fish, coral reef, Hydra, Gonionemus, siphonophora, example and taxonomy of Phylum Cnidaria. It is part of BS Zoology Course Animal diversity.
In this Presentation, Phylum Ctentophora, Comb Jellies is described. After watching this you will learn the characteristics and examples of Phylum Ctentophora. The detail description of Pleurobranchia along with reproduction, colloblasts, mesoglea, comb rows and nerve net. It is part of BS Zoology Course Animal diversity.
In this Presentation, Phylum Platyhelminth, Flatworms is described. After watching this you will learn the characteristics of Phylum Platyhelminthes, Class Turbellaria, Body wall, locomotion, Digestion, Nutrition,Exchanges with the Environment, Nervous and Sensory Functions,Reproduction and Development.
Class Trematoda, Body wall, Subcass, Aspidogastrea, Digenea, Flukes, Lifecycle, Some Important Trematode Parasites of Humans, Chinese liver fluke, Clonorchis sinensis, Fasciola hepatica, sheep liver fluke, Schistosomes and blood flukes. Class Monogenea and Class Cestoidea, tapeworms, Segmented worms, strobili, Some Important Tapeworm Parasites of Humans, beef tapeworm Taeniarhynchus saginatus, broad fish tapeworm and Diphyllobothrium latum, Maintenance of Functions, Reproduction, example and taxonomy of Phylum Platyhelminths. It is part of BS Zoology Course Animal diversity
In this Presentation, Phylum Porifera, Sponge is described. After watching this you will learn the characteristics, Cell Types, Body Wall, Skeletons, Water Currents, Body Forms, Maintenance of Functions, Reproduction, example and taxonomy of Phylum Porifera. It is part of BS Zoology Course Animal diversity
In this Presentation, Phylum Placozoa is described. After watching this you will learn the concept of basal Phyla, description, and example of Phylum Placozoa. It is part of BS Zoology Course Animal diversity.
In this presentation Phylum Acoelomorpha is described. You will learn the concept of basal Phyla, description, and example of Phylum Acoelomorpha. It is part BS Zoology Course Animal diversity.
This is an introductory presentation about zoology. It gives you insight into what's in this field and how to tackle it.
The lecture can be accessed
https://youtu.be/qhXqXaTlMPk
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Delivering Micro-Credentials in Technical and Vocational Education and TrainingAG2 Design
Explore how micro-credentials are transforming Technical and Vocational Education and Training (TVET) with this comprehensive slide deck. Discover what micro-credentials are, their importance in TVET, the advantages they offer, and the insights from industry experts. Additionally, learn about the top software applications available for creating and managing micro-credentials. This presentation also includes valuable resources and a discussion on the future of these specialised certifications.
For more detailed information on delivering micro-credentials in TVET, visit this https://tvettrainer.com/delivering-micro-credentials-in-tvet/
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
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A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Biological screening of herbal drugs: Introduction and Need for
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Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
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Phylum Mollusca, Class Cephalopoda, Locomotion, Digestion,Reproduction, Development learning and Diversity.pptx
1. Dr. Muhammad Moosa Abro
Phylum Mollusca
1
Class Cephalopoda
Shell
Locomotion
Feeding and Digestion
Other Maintenance Functions
Learning
Reproduction and Development
2. 2 CLASS CEPHALOPODA
(Gr. kephale, head, podos, foot) includes the octopuses, squid,
cuttlefish, and nautiluses
the most complex molluscs and, the most complex invertebrates.
The anterior portion of the cephalopod foot has been modified into a
circle of tentacles or arms used for prey capture, attachment,
locomotion, and copulation.
The foot is also incorporated into a funnel associated with the mantle
cavity and is used for jetlike locomotion.
The molluscan body plan is further modified in that the cephalopod
head is in line with the visceral mass.
Cephalopods have a highly muscular mantle that encloses all of the
body except the head and tentacles.
The mantle acts as a pump to bring large quantities of water into the
mantle cavity.
3. 3
The anterior portion of the
cephalopod foot has been
modified into a circle of tentacles
or arms used for prey capture,
attachment, locomotion, and
copulation (figure 11.17).
4. 4
Shell
Ancestral cephalopods probably had a conical shell.
The only living cephalopod that possesses an external shell is
the nautilus
Septa subdivide its coiled shell.
As the nautilus grows, it moves forward, secreting new shell
around itself and leaving an empty septum behind.
Only the last chamber is occupied.
When formed, these chambers are fluid filled.
A cord of tissue called a siphuncle perforates the septa,
absorbing fluids by osmosis and replacing them with
metabolic gases.
The amount of gas in the chambers is regulated to alter the
buoyancy of the animal.
5. 5
Shell
In all other cephalopods, the shell is reduced or absent.
In cuttlefish, the shell is internal and laid down in thin
layers, leaving small, gas-filled spaces that increase
buoyancy.
Cuttlefish shell, called cuttlebone, is used to make powder
for polishing and is fed to pet birds to supplement their diet
with calcium.
The shell of a squid is reduced to an internal, chitinous
structure called the pen. In addition, squid also have
cartilaginous plates in the mantle wall, neck, and head that
support the mantle and protect the brain.
The shell is absent in octopuses.
6. 6 Locomotion
As predators, cephalopods depend on their ability to move quickly using a jet-
propulsion system.
The mantle of cephalopods contains radial and circular muscles.
When circular muscles contract, they decrease the volume of the mantle cavity and
close collarlike valves to prevent water from moving out of the mantle cavity between
the head and the mantle wall.
Water is thus forced out of a narrow siphon.
Muscles attached to the siphon control the direction of the animal’s movement.
Radial mantle muscles bring water into the mantle cavity by increasing the cavity’s
volume.
7. 7 Locomotion
Posterior fins act as stabilizers in squid and also aid in propulsion and steering in
cuttlefish.
“Flying squid” (family Onycoteuthidae) have been clocked at speeds of 30 km/hr.
Octopuses are more sedentary animals.
They may use jet propulsion in an escape response, but normally, they crawl over the
substrate using their tentacles.
In most cephalopods the use of the mantle in locomotion coincides with the loss of an
external shell, because a rigid external shell would preclude the jet-propulsion method
of locomotion described.
8. 8
Feeding and Digestion
Most cephalopods locate their prey by sight and capture prey
with tentacles that have adhesive cups.
In squid, the margins of these cups are reinforced with tough protein and
sometimes possess small hooks (figure 11.18).
All cephalopods have jaws and a radula.
The jaws are powerful, beaklike structures for tearing food, and the radula
rasps food, forcing it into the mouth cavity.
Cuttlefish and nautiluses feed on small invertebrates on the ocean floor.
Octopuses are nocturnal hunters and feed on snails, fishes, and crustaceans.
9. 9
Feeding and Digestion
Octopuses have salivary glands that inject venom into prey.
Squid feed on fishes and shrimp, which they kill by biting
across the back of the head.
The digestive tract of cephalopods is muscular, and peristalsis (coordinated
muscular waves) replaces ciliary action in moving food.
Most digestion occurs in a stomach and a large cecum.
Digestion is primarily extracellular, with large digestive glands supplying
enzymes.
An intestine ends at the anus, near the funnel, and exhalant water carries
wastes out of the mantle cavity.
10. 10
Other Maintenance Functions
Cephalopods, unlike other molluscs, have a closed circulatory system.
Blood is confined to vessels throughout its circuit around the body.
Capillary beds connect arteries and veins, and exchanges of gases, nutrients, and
metabolic wastes occur across capillary walls.
In addition to having a heart consisting of two auricles and one ventricle, cephalopods
have contractile arteries and structures called branchial hearts.
The latter are at the base of each gill and help move blood through the gill.
These modifications increase blood pressure and the rate of blood flow—necessary for
active animals with relatively high metabolic rates.
11. 11
Other Maintenance Functions
Large quantities of water circulate over the gills at all times.
Cephalopods exhibit greater excretory efficiency because of the closed circulatory
system.
A close association of blood vessels with nephridia allows wastes to filter and secrete
directly from the blood into the excretory system.
12. 12
The cephalopod nervous system is unparalleled in any other invertebrate.
Cephalopod brains are large, and their evolution is directly related to cephalopod
predatory habits and dexterity.
The brain forms by a fusion of ganglia.
Large areas are devoted to controlling muscle contraction (e.g., swimming
movements and sucker closing), sensory perception, and functions such as memory
and decision making.
Research on cephalopod brains has provided
insight into human brain functions.
The eyes of octopuses, cuttlefish, and squid are
similar in structure to vertebrate eyes, and
vision is a primary sense that is used in finding
prey and in intraspecific interactions
(This similarity is an excellent example of
convergent evolution.)
13. 13
In contrast to the vertebrate eye, nerve cells leave the eye from the outside of the
eyeball, so that no blind spot exists.
(The blind spot of the vertebrate eye is a region of the retina where no
photoreceptors exist because of the convergence of nerve cells into the optic nerve.
When light falls on the blind spot, no image is
perceived.)
Like many aquatic vertebrates, cephalopods
focus by moving the lens back and forth.
Cephalopods can form images, distinguish
shapes, and discriminate brightness and
patterns.
One species of squid can discriminate some
colors.
14. 14
The nautiloid eye is less complex.
It lacks a lens, and the interior is open to seawater:
thus, it acts as a pinhole camera.
Nautiloids apparently rely on olfaction to a greater extent than do other
cephalopods.
Cephalopod statocysts respond to gravity and acceleration, and are embedded in
cartilages next to the brain.
Osphradia are present only in Nautilus.
Tactile receptors and additional chemoreceptors are widely distributed over the
body.
15. 15
In spite of being colorblind, cephalopods use color and pattern changes in
remarkable ways.
Cephalopods have pigment cells called chromatophores, which are located in
their mantle and body wall.
When tiny muscles attached to these pigment cells contract, the chromatophores
quickly expand and change the color of the animal.
Color and pattern changes, in combination with ink discharge, function in alarm
responses.
In defensive displays, color changes may spread in waves over the body to form
large, flickering patterns.
Pattern changes may also help cephalopods to blend with their background.
16. 16
Color changes are also involved with courtship displays.
Some species combine chromatophore displays with bioluminescence.
Light emission is the result of a symbiotic relationship with bioluminescent bacteria
located within the cephalopod’s mantle cavity.
All cephalopods except nautiloids and members of the octopus suborder Cirrina possess
an ink gland that opens just behind the anus.
Ink is a brown or black fluid containing melanin and other chemicals that is discharged
into exhalent water from the siphon.
Discharged ink confuses a predator, allowing the cephalopod to escape.
For example, Sepiola reacts to a predator by darkening itself with chromatophore
expansion prior to releasing ink.
After ink discharge, Sepiola changes to a lighter color again to assist its escape.
The predator is left with a mouthful of ink.
17. 17
Learning
The complex nervous system of cephalopods contrasts sharply with that of other
molluscs .
Octopuses and cuttlefish have larger brains relative to body weight than any other
invertebrate, fish, or amphibian.
The octopus brain is modified into complex lobes that serve as visual and tactile centers.
Early scientific work on cephalopod learning began in the late 1940s at Stazione Zoologica
in Naples, Italy.
Experiments with Octopus vulgaris demonstrated that this octopus could be trained to
attack, kill, and feed on a crab when presented with certain visual stimuli.
18. 18
Learning
Surgical removal of parts of the brain demonstrated that regions of the brain called
vertical and superior frontal lobes were the learning and memory centers for visual
stimuli.
Since these early experiments, cephalopods have been trained to negotiate mazes;
distinguish shapes, sizes, and patterns in objects; and remember what they have learned.
(Octopuses can remember learned information for up to four months.)
Cephalopods use both chemical and auditory stimuli in their behaviors.
There have been reports of a higher form of learning in octopuses.
Observational learning involves an animal learning by observing other animals
performing a task.
19. 19
Initial reports of observational learning have not been reproduced, and these
investigations continue.
Interpreting all of this information has been very difficult.
The questions of how and why intelligence evolved in the cephalopods are intriguing.
The evolution of intelligence, for example in primate mammals, is usually associated
with long lives and social interactions.
Cephalopods have neither long lives nor complex social structure.
Most cephalopods live about one year (some octopuses live up to four years).
Octopuses are solitary, and squid and cuttlefish school with little social structure.
Most scientists believe that cephalopod brains and intelligence evolved in response
to avoiding predators while living as active predators themselves.
20. 20
Variable food resources present in changing habitats could select for increased
intelligence.
Cephalopods avoid predators by posturing— dangling their arms and tentacles among
seaweed to mimic their surroundings.
Their color changes are used in camouflage and interactions with other cephalopods.
The male Caribbean reef squid, Sepioteuthis sepioldea, uses one grey color display to
attract females and a striping display to ward off competitor males.
21. 21
If a male is positioned between a female and another male, the side of his body facing
the female displays the courtship pattern and the side facing the male displays the
striping pattern.
While color changes are not unusual in animals, they are usually hormonally
controlled.
Chromatophore changes in cephalopods are controlled by the nervous system and can
occur in less than one second.
This combination of nervous system functions is truly unique among the invertebrates
and would not be possible without their large, complex brains.
22. 22 Reproduction and Development
Cephalopods are dioecious with gonads in the dorsal portion of the visceral mass.
The male reproductive tract consists of testes and structures for encasing sperm in
packets called spermatophores.
The female reproductive tract produces large, yolky eggs and is modified with glands
that secrete gel-like cases around eggs.
These cases frequently harden on exposure to seawater.
One tentacle of male cephalopods, called the hectocotylus, is modified for
spermatophore transfer.
In Loligo and Sepia, the hectocotylus has several rows of smaller suckers capable of
picking up spermatophores.
23. 23
Reproduction and Development
During copulation, male and female tentacles intertwine, and the male removes
spermatophores from his mantle cavity.
The male inserts his hectocotylus into the mantle cavity of the female and deposits a
spermatophore near the opening to the oviduct.
Spermatophores have an ejaculatory mechanism that frees sperm from the baseball-bat-
shaped capsule.
Eggs are fertilized as they leave the oviduct and are deposited singly or in stringlike masses.
They usually attach to some substrate, such as the ceiling of an octopus’s den.
Octopuses clean developing eggs of debris with their arms and squirts of water.
Cephalopods develop in the confines of the egg membranes, and the hatchlings are miniature
adults.