They are five pair in numbers
They includes
paired Antennules
Antennae
Mandibles
First maxillae
second maxillae
They are five pair in numbers
They includes
paired Antennules
Antennae
Mandibles
First maxillae
second maxillae
Parental care is any behavior pattern in which a parent invests time or energy in feeding and protecting its offspring.
Parental care is a form of altruism since this type of behaviour involves increasing the fitness of the offspring at the expense of the parents.
The evolution of parental care is beneficial as it facilitates offspring performance traits that are ultimately tied to offspring fitness.
Parental care is evolved in those organism which produce limited no. of eggs to ensure the continuity of their race.
The alimentary canal of Scoliodon comprises:
the mouth,
buccal cavity,
pharynx,
oesophagus,
stomach,
intestine and
rectum opening in the cloaca through anus.
They are five pair in numbers
They includes
paired Antennules
Antennae
Mandibles
First maxillae
second maxillae
They are five pair in numbers
They includes
paired Antennules
Antennae
Mandibles
First maxillae
second maxillae
Parental care is any behavior pattern in which a parent invests time or energy in feeding and protecting its offspring.
Parental care is a form of altruism since this type of behaviour involves increasing the fitness of the offspring at the expense of the parents.
The evolution of parental care is beneficial as it facilitates offspring performance traits that are ultimately tied to offspring fitness.
Parental care is evolved in those organism which produce limited no. of eggs to ensure the continuity of their race.
The alimentary canal of Scoliodon comprises:
the mouth,
buccal cavity,
pharynx,
oesophagus,
stomach,
intestine and
rectum opening in the cloaca through anus.
The nervous system of Pila globosa consists of paired and unpaired ganglia with their commissures and connectives.
The commissures are the nerves that establish connections between similar ganglia, while connectives are the nerves that connect two dissimilar or different ganglia.
The primitive blueprint for the heart and circulatory system emerged with the arrival of the third mesodermal germ layer in bilaterians. Since then, hearts in animals have evolved from a single layered tube to a multiple chambered heart in due course of time.
It discusses basic information regarding a hemichordate animal called Balanoglossus or Acorn worm, which is also a good connecting link between the non-chordates and chordates.
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.
The nervous system of Pila globosa consists of paired and unpaired ganglia with their commissures and connectives.
The commissures are the nerves that establish connections between similar ganglia, while connectives are the nerves that connect two dissimilar or different ganglia.
The primitive blueprint for the heart and circulatory system emerged with the arrival of the third mesodermal germ layer in bilaterians. Since then, hearts in animals have evolved from a single layered tube to a multiple chambered heart in due course of time.
It discusses basic information regarding a hemichordate animal called Balanoglossus or Acorn worm, which is also a good connecting link between the non-chordates and chordates.
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.
FYBSc course-I, semester-II, Ethology, question bank is for reference of B N Bandodkar college of Scince, Thane. Pl do not consider these question as IMP. This may help preparing for the forthcoming examination, All the best!!!
The percentage frequency of occurrence (F) revealed the
predominance of ‘P Wo’, and Mol in both the
water bodies, indicative of main food items.
Feeding index (IA) shows high percentage of ‘P Wo’, ‘Mol’ and ‘NF’ in food compositionof M. gulio which attributed to vacuity index (VI). Both ‘NF’ being compensatory food and
conspicuous VI in feeding of M. gulio ascribed to the higher pollution in TC as compared toURE. The food selection habit of M. gulio was corroborating with the pollution status of theambient water bodies
Abstract:
It has envisaged to make available the information on a season-wise pooled data of the feeding habits of
Boleopthalmus dussumieri (Cuv. & Val) studied along the Ulhas river estuary using point method during the period of two years from July 2004 to June 2006,. The qualitative and quantitative analyses of stomach content were carried out to calculate percentage frequency of occurrence of food items
(F)
, feeding index
(IA)
and vacuity index
(VI).
. Electivity analysis showed that the fish is herbivorous feeding mainly on diatoms and other species of algae.
Food selection depends on the energy strategy of the feeder. The food size, quantity and quality varies with species to species and also depends on the ability of feeder, its body size etc.
Feeders are either specialists or opportunists. Food selection depends on competitive principle, learned aversion and food energy budget.
Resources are defined as matter, space and time utilized for the wellbeing of mankind is called as resources. The natural resources are materials, which living organisms can take from nature for sustaining their life or any components of the natural environment that can be utilized by man to promote his welfare is considered to be natural resources.
Chordata is an assemblage of heterogeneous animals which differ widely in their characteristics but have a few common features like they have notochord, dorsal tubular nerve cord, pharyngeal gill slits and post-anal tail. The notochord is a cartilaginous skeletal rod present at some stage in their life cycle. Nerve cord is mid-dorsally placed and is hollow containing axial nerve canal. Pharynx is perforated containing several gill slits primarily were used for filter feeding but later evolved as respiratory in function in aquatic forms.However, in terrestrial forms they disappear in adults but are occurred in embryonic stages. The body extends beyond anal terminal to give rise to a balancing or important part in locomotion called as tail.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Insect are animals , but unlike many animals , they have no backbone .
They have an outer support system called an exoskeleton rather than the inner support system ( endoskeleton ) characteristic of most large animals .
Crash-Course for AIPMT & Other Medical Exams 2016 (Essentials cockroach)APEX INSTITUTE
Dear Students/Parents
We at 'Apex Institute' are committed to provide our students best quality education with ethics. Moving in this direction, we have decided that unlike other expensive and 5star facility type institutes who are huge investors and advertisers, we shall not invest huge amount of money in advertisements. It shall rather be invested on the betterment, enhancement of quality and resources at our center.
We are just looking forward to have 'word-of-mouth' publicity instead. Because, there is only a satisfied student and his/her parents can judge an institute's quality and it's faculty members coaching.
Those coaching institutes, who are investing highly on advertisements, are actually, wasting their money on it, in a sense. Rather, the money should be invested on highly experienced faculty members and on teaching gears.
We all at 'Apex' are taking this initiative to improve the quality of education along-with each student's development and growth.
Committed to excellence...
With best wishes.
S . Iqbal
( Motivator & Mentor)
Similar to Scoliodon laticaudus: Spadenose shark -Notes for T.Y.B.Sc. Sem VI (20)
This patent was registered with Govt of India in 2014.
The patent emphasizes on the remedy of Acne vulgaris which is a stubborn disease of facial surface. The topical treatment of admixture of extract from Tinospora cordifolia (Indian tinospora) and chitosan nanoparticles was effective remedy on Acne vulgaris.
In the present invention a novel method of large scale production of Iron and Iron Oxide nanoparticle is invented using extract of lac (an animal Secretary Product). Method is one easy, less ingredient involving, cheap, ecofriendly, less energy consuming and help in production of Iron and Iron Oxide nanoparticle on large scale. This is the first successful method of preparation of Iron and Iron Oxide nano particles from extract of lac and or waste product of lac industry.
Relationship of qualitative and quantitative fisheries diversity with the environmental variables was studied for the period of two years along the three zones, viz. upper, middle and lower, of the Ulhas River estuary. Total ten hydro-sedimentological parameters were analyzed on monthly basis from each zone to depict ambient pollution level. Zones with comparatively higher pollution level deterred fisheries landings. The principal coordination analysis (PCO) ordination and zonewise K-dominance curves revealed the direct correlation of fish diversity with the existent spatial environmental conditions of the Ulhas River estuary.
Keywords: hydrological conditions, parameters, water pollution, Ulhas River, estuary, fisheries, diversity, landings, water color, phosphates, nitrates, DO, BOD, organic carbon, silt, principal coordination analysis.
NTCA (National Tiger Conservation Authority) was founded by former Prime minister Indira Gandhi to save tiger. This body promotes the conservation on the basis of Wildlife (Protection) Act 1972.
Project tiger was launched in 1973. Initially 9 suitable habitats were selected later it increased to 47.
Objective was to conserve forest and biodiversity, through intensified protection; conservational development and strengthening research activities
India has diverse biomes like tropical rain forest (jungles), alpine forest, desert, marsh land, islands, deltas, savannas, scrub lands etc.
Wildlife of India has been gifted by very diverse flora and fauna.
It is our prime duty to conserve and sustain it for forthcoming generations.
World is loosing one species everyday.
Science means ‘to know’.
To gain knowledge through the mode of thinking and experimenting with reasoning.
Ideas are tested and hypotheses are set and finally the concept is accepted or rejected.
Person involved in these activities is known as ‘scientist’.
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.
The gunwale is a nautical term describing the top edge of the side of a boat.
The bow is a nautical term for the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway.
The opposite to the bow of boat is called the stern.
A deck is a permanent covering over a compartment or a hull, which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface.
The mast of a sailing vessel is a tall, vertical or near vertical spar, or arrangement of spars, which supports the sails.
Organisms in the water, especially saltwater, attach to slick surfaces like a boat's hull. It doesn't take long for a boat hull to become slimy with algae. Algae pave the way for adherence of other organisms. The general term for organism on a boat hull is fouling. Fouling makes boats drag, use more fuel and harder to maneuver. Invasive organisms spread by hitching a ride on the underside of a boat. Common marine foulers include barnacles, algae, shellfish, tunicates, ship-
worms, gribbles etc.
Wood borers are highly specialised animals which penetrate wooden structures such as boats, wharves, jetties, driftwood and even living mangrove trees. Many can digest the wood owing to cellulose-digesting bacteria or protozoa living in their guts. Only a few species can actually produce their own cellulose-digesting enzymes (cellulases).Wood borers are insects that chew their way into the solid trunk of a living tree or into a wooden structure, such as an old boat or house. Healthy trees are rarely attacked by wood borers, but a diseased or dying specimen can often host these kinds of invaders. The same goes for old houses and boats, where rain-soaked or rotten wood is more susceptible to invasion.
Temperature, light, Oxygen, salinity, pH are important marine factors which impact the major life and physical properties of the oceans. These factors make the marine environment a dynamic entity and otherwise impacting on the terrestrial ecosystems too.
Gill net
Trawl
Purse seine net
Hooks and lines
TED (turtle exclusion devices)
Non-conventional fishing methods:
light fishing; hose pipe fishing; electric fishing.
Pelagic (surface/open ocean) gillnets are systems of netting with highly specific mesh sizes. Gillnets as long as 2.5km, are placed vertically in the water column with the use of buoys and weights. These nets may be anchored or allowed to drift with prevailing currents, intercepting migrating sharks and fishes such as tuna and mackeral. Large fish become entangled or gilled in the net (commonly around the gills), whilst smaller fish are able to pass through the designated mesh size.
This article includes Basics classification like binomial nomenclature, Taxa hierarchic, Five kingdoms of Robert H. Whittaker, Levels of Organization, and Classificationa and features of Protozoa, Porifera and Coelenterata
Temperature as ecological factor its impact on animal life.
Animals can tolerate temp. from -10 to 50 ⁰C
Praying mantis can survive at 62 ⁰C whereas certain bacteria can live at 90 ⁰C.
Animals tolerating diff. range of temperature.
Stenothermal and eurythermal organisms.
Enzymatic activity are controlled by certain temp ranges. E.g. Human 30 to 40 ⁰C.
Reproduction is controlled by temperature
Activities are controlled by temp. hibernation, aestivation and migration.
Morning lower temp. make animals sluggish.
Animals are distributed according to temp. tolerance in terrestrial and aquatic body (thermocline).
Visible light – Photosynthesis
Infra red light – Warmth of earth at high altitudes
Ultraviolet light – Ionosphere (Ozone layer)
Light reaching earth depends on angle of incidence, altitude, latitude, season, clouds, fog, suspended particles, dust, water drops, smog (pollution) and time of day.
Ethology is the scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Ethology is a branch of zoology concerned with the study of animal behavior. Ethologists take a comparative approach, studying behaviors ranging from kinship, cooperation, and parental investment, to conflict, sexual selection, and aggression across a variety of species.
Conservation involves maintenance of the natural environment of man including the infinite resources of air, water, soil and life forms. Conversation also involves the collective responsibility of governments, private organizations, industries and individuals and the setting aside of funds, finances for ecological research and execution of conservation projects.
Fundamentals of Aquarium Setting for Beginners. Historic
Social
Aesthetic and ornamental
Meditating
Commercial
Educational, Scientific and Research
Setting up of aquarium
Maintenance of aquarium
Accessories required
Decorative used
Types of fish
Boleophthalmus dussumieri (Val., 1837) is a mudskipper species inhabiting, in abundance on the intertidal
mudflats occurred on either banks of Ulhas River estuary. The present study scan and focal sampling method
implied to record the lagged immergence of B. dussumieri on the surface during ebb-tide. The study revealed
direct correlation with the declining water level and rate of exposure of the mudflat during the ebb-tide
occurred at Kolshet creek along the west bank of the Ulhas River estuary. PCO obtained with Euclidean
distance matrix represented 100% ordination of the samples depicting that the level of water defined the rate of
surficial emergence of individuals.
Ulhas River Estuary (URE) sediment is highly silted. Boleophthalmus dussumieri (Val., 1837) is a mudskipper
species of a common occurrence on the intertidal mudflats developed on either banks of URE. The present study
recorded the various activities like burrow construction, feeding, territoriality and courtship, of B. dussumieri
using scan and focal sampling method on the surface during tidal movements on the exposed mudflats of URE
near Kolshet creek. Although the breeding and territoriality of B. dussumieri being normal, the other
behavioral activities such as courtship, construction of burrows and survivorship were different as compared to
the earlier observations by various experts. Breeding pairs preferred to develop burrows at spring tide limits.
Burrows lacked chimneys and pit-pools. Juveniles remained without burrows and were found to secure position
by penetration in loose soil during flood tide. Feeding on muddy surface was performed by strange straining
behaviour.
More from Dr. Sudesh D. Rathod, B N Bandodkar College of Science (20)
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
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.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
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.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
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.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Scoliodon laticaudus: Spadenose shark -Notes for T.Y.B.Sc. Sem VI
1. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
SCOLIODON LATICAUDUS
Spadenose shark
Systematic position
Kingdom: Animalia
Phylum:
Chordata
Class:
Subclass:
Order:
Family:
Genus:
Chondrichthyes
Elasmobranchii
Carcharhiniformes
Carcharhinidae
Scoliodon
Species:
Synonyms
Carcharias muelleri
J. P. Müller & Henle,
1839
Carcharias palasoora
Bleeker,
1853
Carcharias sorrahkowah Bleeker,
1853
Carcharias sorrakowah Cuvier,
1817
S. laticaudus
Reference Book: ‘On the spadenose shark,
‘SCOLODON LATICAUDUS’
-by R. V. Ranade
Habit & habitat
Scoliodon laticaudus is marine; brackish; demersal; amphidromous shark. It is typically found in coastal
waters at 10–13 m (33–43 ft) deep, often close to rocky bottoms and in lower reaches of tropical rivers. It is
uncertain, however, if this species can live in perfectly fresh water for extended periods. They form large
unisexual shoals for feeding purpose. It feeds on shrimps, small benthic fish, cephalopods and crabs.
Viviparous, with an unusual columnar placenta; litter size varies from 3 to 14.
Distribution
Indo-West Pacific, Scoliodon laticaudus is found in Eastern Africa near Somalia, Tanzania, Mozambique.
Scoliodon laticaudus is native of Bangladesh; Borneo; Cambodia; China; India; Indonesia; Japan; Macao;
Malaysia; Myanmar; Oman; Pakistan; Thailand; Philippines; Singapore; Bangladesh; Sri Lanka; Taiwan,
Province of China; Thailand; Viet Nam. Apparently absent from Australasia and Oceania. Kasim (1991)
reported that the annual recorded catch of Spadenose Shark in the Veraval coast, India from 1979-1981
averaged 823 tons. These were taken mostly by trawl and gillnet fishing as by-catch. Along Mumbai coast
spadenose are found to about five kilometers area.
External characters
Body moderately stout, fusiform in shape and can be distinguished into head, trunk and tail; color bronze
grey above, white below, fins sometimes darker than body; no conspicuous markings. Head broad, greatly
depressed, eyes and nostrils small. First dorsal fin extends up to or beyond middle of pelvic fin. Pupil vertical
and nictitating eyelid is in anterior and lower corner of eye. Nostrils are closer to mouth than the snout.
Mouth is ventral, crescentic, lined by indistinct upper jaw but a well-defined lower jaw. Gills are five pairs
and without operculum. Two dorsal, a pair of pectoral, a pair of pelvic, one ventral and one caudal fin are
present. Caudal is heterocercal and bears a crescent shaped depression called as precaudal pit. In males the
inner margin of each triangular pelvic fin is rolled forming a finger-like tapering appendage, the clasper
1
2. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
or myxopterygium. Shark grows maximum about 74 cm, but mostly found smaller in size. Body size at
birth is 12 to 15 cm.
Skin
The integument provides a characteristic form to the body. It also protects the enclosed organs. Skin is very
tough, slimy and firmly attached to underlying muscle coat. Skin is comprised of outer epidermis and inner
dermis. Epidermis is derived from ectoderm and dermis from mesodermal layer of the embryo. The
epidermis has stratified epithelium and consists of basal germinativum layer of cuboidal cells followed by 45 layers of progressively flattened cells and cornification is not complete. The outermost layer forms a
squamous epithelium. In the epidermis may have mucus secreting glands. Unicellular mucous glands are
present in the dermis. Dermis has no layers but is made of scattered cells embedded in connetive tissue, and
contains chromatophores. They are of two types 1) black, stellate and highly branched melanophores 2)
rounded or oval yellowish xanthopohres.
Exoskeleton
Exoskeleton is comprised of tiny, microscopic placoid scales also known as dermal denticles because their
structural organization is similar to that of the vertebrate teeth. Placoid scales cover entire body of shark
except inner margin of the claspers. It is suggested that close placement of placoid scales channel water
resulting in a laminar flow that acts to reduce friction and also make shark hydro-dynamically quiet while
stalking prey. Each placoid scale is made up of a basal plate and a crown. Basal plate is embedded in dermis
and has an opening of pulp cavity on its ventral side which leads to the spines of crown and supply nutrition
from dermis for growth. The tridentate crown projects outside the skin and is protective to skin. The
outermost layer of crown is made of enameloid or vitrodentine material. The inner layer is called as
dentine.
2
3. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Arrangement of placoid scales in shark
Structure of placoid scales
side view
Endoskeleton
Endoskeleton of Scoliodon laticaudus is formed of axial skeleton and appendicular skeleton.
Axial skeleton includes vertebral column and skull.
Vertebral column of Scoliodon laticaudus is made of amphicoelous type of vertebrae i.e. they have
concavity on either side of the centrum. Vertebrae are divided into two groups, anterior group of trunk
vertebrae and posterior group of caudal vertebrae.
1. Trunk vertebra
It comprises a neural arch around spinal cord, a centrum and a pair of ventro-laterally placed
transverse processes. Transverse processes in trunk vertebrae articulate with cartilaginous ribs
about half an inch length. The top of neural arch is known as neural spine. The vertebral neural
plates are in the adult fused with their respective centra, and are notched behind for the exit of the
ventral (motor) roots of the spinal nerves. The intervertebral neural plates are
1. Neural spine,
2. Neural arch,
3&12. Neural canal,
4 &13. Concave centrum,
5. Focus,
6. Haemal arch,
7. Haemal canal,
8. Haemal spine,
9. vertebral Neural plate,
10&11. Inter-vertebral neural plate,
15&16. Transverse processes
3
4. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
polygonal pieces alternating with the vertebral neural plates; they are notched behind, but at a more
dorsal level than are the vertebral neural plates, for the exit of the dorsal or sensory roots of the
spinal nerves.
2. Caudal vertebra
In caudal vertebra the transverse processes instead of projecting laterally, are bent inwards beneath
the centrum and meet and fuse in the mid-ventral line to form the haemal arch. Haemal arch
encloses a haemal canal and is projected ventrally as haemal spine, supporting the caudal fin. The
posterior part of vertebral column is bent upward to support asymmetrical tail, known as
heterocercal tail.
3. Skull
Skull consists of a cranium with a flattened floor and a more irregular and incomplete roof. Its sides
are expanded in front owing to the olfactory capsules, and behind owing to the auditory capsules,
while in the middle they are deeply hollowed to form the orbits or eye-cavity.
Dorsal view
Ventral view
The dorsal and ventral boundaries of the orbits are respectively formed by the prominent supra-orbital and
suborbital ridges. Posteriorly it has a wide opening, the occipital region. Anteriorly it gives off three long
processes which fuse together terminally to form the rostrum (two dorso-lateral and one ventro-median
cartilages). Behind the olfactory capsules comes a large, nearly circular, hole, the anterior frontanelle above
cerebrum on cranium. Behind above cerebellum chanber is a small dorsal opening called parietal fossa.
Olfactory capsule lies behind rostrum. The olfactory capsules have no ventral walls, and are separated from
one another by the internasal septum. It encloses the olfactory chambers and is open ventrally.
Behind the olfactory capsules comes a large, nearly circular, hole, the anterior frontanelle, slightly behind
which are the two ophthalmic foramina. The dorsal and ventral boundaries of the orbits are respectively
formed by the prominent supra-orbital and suborbital ridges. Behind are the auditory capsules, each of
which is marked by a pair of prominent ridges, which lodge respectively the anterior and posterior vertical
semicircular canals of the ear.
A number of ventral structures disconnected or only loosely connected with the cranium. These together
constitute the visceral skeleton forming the jaws and supporting the gills.
4
5. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Appendicular Skelton of shark includes pectoral and pelvic girdles
1. Pectoral Girdle
Two pectoral girdles are attached to the coracoid bar
on either side on the ventral side of the shark just
behind the gills. The paired scapular cartilages, and
their extensions, the suprascapular cartilages, extend
dorsally from their base at the lateral ends of the
coracoid bar, near the fin, on either side of the body in
the muscular wall. The glenoid surface is the surface of
articulation between the fin base and the coracoid bar.
Proximally fin is comprised of propterygium,
mesopterygium and metapterygium from outer to inner
side which articulates distally to their corresponding
radials. outline of the distal part of is supported by
horny fin-rays called as ceratotrichia.
2. Pelvic Girdle
Pelvic girdle is present in the posterior side of the body to which the pelvic fins are attached. The pelvic
girdle is connected directly to the vertebral column in the sacral region. The pelvic girdle has two equal
halves which are known as 'ossa innominata'. Each as innominatum is formed by three bones. They
are the dorsal bone ilium, the ventral bone ischium and the antero-ventral bone pubis. The pelvic girdle
has a depression at the junction of the three bones. It is termed as acetabulum into which the head femur
of the hind limb articulates and forms a ball and socket joint. Form acetabulum it projects a long curved
shaft, basipterygium. Basipterygium gives out a series of radiales. Posteriorly basipterygium is attached
with claspers in male shark.
1.
Ischio-pubic bar of pelvic girdle
2.
Basipterygium
3.
Clasper
4.
Radiale
Fig. 8. Dorsal view of the pelvic girdle and fins of a male Scoliodon laticaudus
5
6. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Digestive system
Buccal cavity is the area enclosed by the jaws (mandibular arch) and the cartilage of the throat (hyoid arch).
The triangular sharp teeth are arranged in several rows beginning at the outer edges of the upper and lower
jaws. Behind the functional teeth are additional rows folded downward ready to replace any that are lost.
The pharynx is the portion of the alimentary canal posterior to the hyoid arch and has five pairs of gill and
also contains the tongue in dogfish. The shark can bring water into its pharynx to the gills by way of the
spiracle and mouth. The raised floor of the oral cavity is referred to as the tongue. The tongue of the shark is
practically immovable and without muscles. It is
supported anteriorly and posteriorly by cartilage and
hence referred as false tongue. Posteriorly it narrows
to form the esophagus.
The esophagus is the short hollow tube connecting the
pharynx to the stomach. The esophagus is the thick
muscular tube extending from the top of the cavity
connecting the oral cavity and pharynx with the
stomach. The esophagus is lined with papillae, which
form a tight seal to keep water out.
The esophagus leads into the "J"-shaped stomach. The
upper portion, the cardiac region, continues as the
main body, and ends at the duodenal end. The mucosa
is the inner lining of the stomach. The rugae are
longitudinal folds that help in the churning and mixing
the food with digestive juices. A circular muscular
valve, the pyloric sphincter, is located at the far end
or pyloric end of the stomach. It regulates the passage
of partially digested food into the intestines.
The pancreas is located on the duodenum and the
lower stomach. The secretions of the pancreas enter the duodenum by way of the pancreatic duct. The liver
is the largest organ lying within the body cavity. Its two main lobes, the right and left lobes extend from the
pectoral girdle posteriorly most of the length of the cavity. A third median lobe much shorter lobe and
contains the green gall bladder along its right edge. The dark, triangular-shaped spleen is located near the
posterior end of the stomach. Although a part the lymphatic system, the spleen is closely associated with the
digestive organs in all vertebrates.
The small intestine is composed of, anteriorly, a duodenum, and posteriorly, an ileum (valvular intestine).
The duodenum is a short "U"-shaped and connects the stomach to the intestine. The bile duct from the gall
bladder enters the duodenum. The valvular intestine is the second and much larger portion of ileum, which
contains a scroll valve. The scroll valve is the longitudinal fold hanging from roof of ileum which is coiled
within the valvular intestine. It adds surface area for digestion and absorption to an otherwise relatively short
intestine.
The large intestine, rectum or colon, a shorter section than the small intestine has a rectal gland entering it.
The rectum is the narrowed continuation of the valvular intestine. It is located at the posterior end of the
6
7. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
body cavity. The rectum, the most posterior portion, ends in the anus which projects into the cloaca, a
common opening with the urogenital ducts.
The rectal gland is a slender, blind-ended, finger-like structure that leads into the rectum by means of a duct.
It has been shown to excrete salt (NaCI) in concentrations higher than that of the shark's body fluids or sea
water. It is thus an organ of osmoregulation, regulating the shark's salt balance.
The cloaca is the last portion of the alimentary canal. It collects the products of the colon as well as the
urogenital ducts. It is a catch-all basin leading to the outside by means of the cloacal opening.
Respiratory system
In Scoliodon respiration takes place through 5 pairs of gill slits or gill pouches. They are present in a series
on the wall of pharynx on either lateral side, behind the hyoid arch. Each gill pouch opens into the pharynx
by a large branchial aperture and to outside through an external branchial aperture or gill slit. Two adjacent
gill pouches are completely separated by a vertical fibro-muscular partition, the interbranchial or gill
septum. The inner or pharyngeal border of each gill septum is supported by a cartilaginous visceral arch or
gill arch with its slender branchial rays. The septum is covered by epithelium and contains blood vessels,
nerves etc.
Gill chamber of shark
Respiratory system of shark
The mucus membrane of a septum is raised into numerous horizontal leaf like folds called gill lamellae or
gill filaments. These constitute the gill proper and are richly supplied with blood capillaries. Each septum
bears two sets of gill-lamellae, one on its anterior face and the other on its posterior face. Each set makes a
half gill called hemibranch. A gill pouch thus contains two hemibranchs belonging to two different adjacent
gills. These two hemibranchs with their interbranchial septum and the visceral arch constitute a complete gill
or holobranch. The posterior hemibranch of each holobranch is larger than the anterior one. In Scoliodon,
the hyoid arch bears only a hemibranch posteriorly.
The first four branchial arches bear a holobranch each. Thus scoliodon has total nine hemibranchs while the
fifth branchial arch is devoid of gills and is called abranch.
The inner part of each interbrachial septum has a supporting visceral arch from which cartilaginous gill rays
arise in a single row and project into the interbranchial septum for further support. Visceral arches also give
out rigid comb-like gill rackers, which project the internal branchial apertures from food.
7
8. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Blood vascular system
Sharks have a two-chambered heart, with an atrium (also called the auricle) and a ventricle. The heart is an
S-shaped tube that is located in the head region of the shark. It is located at ventrally in thoracic pericardial
cavity lined by a thin pericardium. The blood is pumped by the heart through the afferent branchial arteries
(ventral aorta) to capillaries in the gills (where the blood is oxygenated). The blood then flows through
efferent branchial arteries (paired dorsal aorta), then through the tissues of the body, and then back to heart in
veins.
1. Heart of shark
The shark heart is two chambered heart having single atrium and a single ventricle. The heart of a
shark contains four important parts, the atrium and ventricle, the sinus venosus, and the conus
arteriosus. The sinus venosus is a small sac with thin walls which collects deoxygenated blood from
the fish’s veins, after which the blood flows into the atrium, a large muscular chamber. The atrium is
a one-way compartment for blood to flow into the ventricle (which does the pumping for the heart).
The bulbus arteriosus is a large tube into which the blood is pumped from the ventricle. The Conus
arteriosus then leads the blood to the ventral aorta, through which blood flows to the shark’s gills
2. The Aortic arches
The anterior end of the conus arteriosus continues forward as the ventral aorta. It gives off five
pairs of afferent branchial arteries which carry deoxygenated blood from the heart to the gills.
Each arterial collector loop is formed from the union of a pre-trematic artery from the anterior
side of a gill slit with a post-trematic artery from the posterior side of the gill slit. The pre and posttrematic arteries receive tiny branches from the adjacent gill lamellae and both join together to give
rise to an efferent branchial artery. The four pairs of efferent branchial arteries collect
oxygenated blood from the gills. The four pairs of efferent branchial arteries join at the mid-dorsal
line to form the large dorsal aorta.
3. Arterial system:
Internal carotid artery Supplies brain; Dorsal aorta supplies entire trunk; Hyoidian artery supplies
carotid arteries; Pharyngoesophageal artery supplies esophagus and pharynx; Subclavian artery
supplies pectoral fin; Coeliac artery supplies gonads and entire digestive tract; Gastric artery supplies
stomach; Hepatic artery supplies liver; Ovarian artery/testicular artery supplies gonads;
Pancreaticomesenteric artery supplies pancreas and intestine; Anterior intestinal artery supplies
intestine; Anterior mesenteric artery supplies intestine; Gastrosplenic artery supplies spleen,
stomach, and pancreas; Iliac artery supplies pelvic fins.
8
9. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
1. Venous system:
Hepatic portal vein drains entire nutrient rich blood from digestive tract to liver which break into
capillaries; Gastric vein drains stomach; Pancreaticomesenteric vein drains intestine, spleen, and
pancreas; Anterior intestinal vein drains intestine; Anterior lienogastric vein drains spleen and
stomach; Leinomesenteric vein drains pancreas; Posterior intestinal vein drains intestine;
Posterior cardinal vein drains kidneys; Posterior cardinal sinus drains entire trunk.
Nervous system
1. Brain
Prosencephalon (forebrain) - subsequently divides into the telencephalon (cerebrum) &
Diencephalon (epithalamus, thalamus, & hypothalamus)
Mesencephalon (midbrain) - develops without further subdivision & forms the tectum
Rhombencephalon (hindbrain) - subdivides into the metencephalon (pons & cerebellum) and
myelencephalon (medulla oblongata)
a. Forebrain: Sharks have very well developed olfactory lobes, a mid-brain with a thalamus,
hypothalamus, pituitary gland, amygdala and a large pallium (forerunner of the cortex)
with well-defined basal ganglia, although the hippocampus has not much differentiated.
b. Midbrain: There are two large optic lobes situated on top of the midbrain.
c. Hindbrain: The hind-brain has a well developed brainstem with a large, elongated
cerebellum. Posteriorly it gives out a pair of auricles of cerebellum and medulla
oblongata which encloses fourth ventricle; and finally gives out a dorsal tubular spinal
cord.
9
10. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
2. Cranial nerves
Terms
Olfactory nerve
Optic nerve
Origin
Definitions
Olfactory lobe Cranial nerve I, terminates in the olfactory bulb
Optic lobe
Oculomotor nerve Optic lobe
Cranial nerve II, arises in the retina and extends to the
diencephalon and then to the optic lobes
Cranial nerve III, innervates 4 eye muscles (inferior oblique,
superior, inferior and medial recti)
Betn. Optic &
Cranial nerve IV, innervates the superior oblique muscle
cerebellum
Internal
Cranial nerve V, (3 branches): opthamalic, maxillary,
Trigeminal nerve surface of
mandibular
medulla
Ventral surface
Abducens nerve
Cranial nerve VI, innervates the lateral rectus
of medulla
Common with Cranial nerve VII, (3 branches) arises from the medulla and
Facial nerve
trigeminal
base: superficial ophthalmic, buccal nerve, hyomandibular
Cranial nerve VIII innervates the inner ear by means of a
Medulla
Statoacoustic
vestibular branch to the anterior part of the ear and a saccular
(Auditory)
branch to the posterior part
Cranial nerve IX, has multiple branches, innervates the the
Glossopharyngeal
Medulla
third visceral arch
nerve
Cranial nerve X, gives off lateral line trunk and four branchial
Vagus nerve
Medulla
rani to each of the remaining gills
Medulla
Cranial nerve XI, accessory to vagus….Motor
Accessory
Trochlear nerve
Medulla
Hypoglossal
Cranial nerve XII, tongue muscles ………….Motor
10
11. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Receptor organs of shark
1. Skin (general cutaneous sense organs):
Skin has numerous free nerve endings enabling shark for the reception of sense of touch, pain and
temperature in the exterior. There are some touch corpuscles present at the bases of the fins.
2. Lateral line system (LL) and neuromasts:
LL system includes a network of canals and sense organ called as neuromast. Two longitudinal
canals run laterally along the flanks of the body from the tip of the caudal fin towards the anterior of
the shark. These lateral longitudinal canals divide into cephalic and orbital canals in the head
region. Orbital canals re-divide into supra-orbital and infra-orbital canals. Both supra orbital and
infra-orbital canals divide further and from a network on the head. Longitudinal canals also unite by
a transverse commissural occipital canal at the junction of head with trunk.
Neuromasts are special sense organs present in aquatic organisms. They are arranged in a series
along the LL canals. Each neuromast is a spherical or flask like hollow body located in a fibrocartilage. Internally it has a layer of connective tissue except its base. At the base it contains a lower
layer of sensory cells (hair cells) embedded in supporting cells and an upper layer made of
vacuolated gelatinous cells called as cupula. Cupula remains in close contact with the sensory cells.
Each sensory cell has sensory projections, a kinocilia and few stereocilia. When water enters in
canal system cupula displaces and bends kinocilia sending the impulses to axons attached to sensory
cells.
11
12. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
3. Electroreceptors (ampullae of Lorenzini)
The ampullae of Lorenzini are small vesicles that form part of an extensive subcutaneous sensory
network system. These vesicles are found around the head of the shark. These are modified LL
organs and respond to detect weak magnetic fields produced by other fish at short ranges. This
enables a shark to locate prey buried in the sand or to orient to nearby movement. Each ampulla is a
bundle of sensory cells innervated by several nerve fibers. These fibers are enclosed in a jelly-filled
tubule that has a direct opening to the surface through a pore. These pores on the head of the shark
are visible to the naked eye, and appear as dark spots. These are two type ampullary and tuberous
receptors.
Ampulla of Lorenzini has a flask like ampullary sac with a long tube and is filled with gelatinous
substance. There are few chambers in the ampullary sac containing sensory cells which are
connected to neurons ventrally. A series of ampullae of Lorenzini are embedded in connective tissue
are mostly found in the head region. Tuberous organs lack the ampullary sac. In the marine water a
weak electric field is generated naturally in number of ways are received by shark to differentiate
between the objects event in the dark.
4. Internal ear
Only internal ear is present in shark. It is also called as
membranous labyrinth. Labyrinth is enclosed in auditory
capsule of the cranium floating in perilymph. It is made of
a vertical flattened utriculus and ventral sacculus.
Utriculus has outgrowths forming three semicircular
canals lying perpendicular to each other namely anterior,
posterior and horizontal canal. Sacculus gives out a
posterior outgrowth called lagena. The cavity of entire
12
13. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
labyrinth is filled with fluid called as endolymph. Membranous labyrinth has four functions i.e.
controls musculature; change in direction during swimming; to regulate depth and sound reception.
5. Olfactory sac
There are two olfactory organs/sacs/chambers. Each olfactory organ is located in olfactory capsule of
skull which is guarded by a nasal fold. There is an incurrent opening placed anteriorly and an
excurrent canal posteriorly. Olfactory chamber has about 40 parallel, vertically arranged olfactory
folds or ridges internally. Each olfactory ridge gives out numerous lateral alternating leaflets like
outgrowths lined by olfactory epithelium. These outgrowths increase the surface area. The
epithelium is lined by olfactory chemoreceptor cells. Sense of smell is acute in shark at a capacity
to detect upto 1 ppm dilution (1 part in million parts of sea water). Taste buds are also similar to the
olfactory receptors but they are not distant field chemoreceptores.
6. Eye: In Scoliodon laticaudus have laterally
positioned eyes. Scoliodon laticaudus is
considered to have generally small eyes
compared to body size. The outer layer of the
shark eye comprises a thick cartilaginous
sclera. Shark eyes need to handle wide water
pressure variations, as they range from shallow
to deep water looking for food. Shark eyes
have a large, spherical lens, a cornea, a retina
(with both rods and cones), an iris, and a pupil.
The retina has a greater proportion of rods
(light intensity sensors) than cones (color
sensors), so Scoliodon laticaudus very sensitive
to small differences in light intensity (dark
versus light). They even have good vision in
dim light. Scoliodon laticaudus has a mirrorlike layer in the back of the eye, the tapetum
lucidum. This layer doubles the intensity of incoming light, enhancing light sensitivity. Unlike other
fish, shark's pupils can dilate and contract to control the amount of incoming light. Scoliodon has a
nictitating membrane, a type of eyelid that protects the eye during hunting. External eyelids are
immovable.
13
14. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
Urogenital system
1. Male urogenital system:
The kidneys are flattened; ribbonlike, dark colored structures lying dorsally on either side of the midline,
along the entire length of pleuroperitoneal cavity and deeply placed dorsally. The upper portion of kidney is
rounded known as head of kidney is an active part of reproductive system. The male reproductive system
begins in the testes. These sex organs are located in the dorsal side of the shark next to the liver; however, the
testes are noticeably larger than the ovaries. The size of the testes, however, varies in size depending on the
month of the year (they are larger during the breeding months of January and February). The function of the
testes is to produce sperm that will later be used to fertilize the female ova. The sperm is taken from the
testes to the Archinephric Duct by few small tubes known as Vasa efferentia. The vasa efferentia dilate to
form a vide vas defferens transports sperm to the Seminal Vesicle. The Seminal Vesicle is directly attached
to the spiralled Archinephric Duct and is noticeably larger and straight. The Seminal Vesicle leads to the
Sperm Sac. The Sperm Sac is the last stop before excretion in the male reproductive system. The Sperm Sac
contains seminal fluid that will allow the sperm to pass safely to the female and fertilize the ova. The entire
embryonic developmental stage occurs in the female. For this reason, males must have developed certain
structures that allow them to fertilize the female egg (equivalent to the male penis). This structure is known
as the Clasper. The Clasper allows the male shark to hold on to the female shark during sexual reproduction.
Each Clasper posses a Clasper Groove, allowing the Clasper to bend at possible awkward angles. Also part
of the Clasper structure is the Siphon Sac. All of these structures are essential during sexual reproduction.
To start off sexual reproduction, the Siphon Sac absorbs some seawater. This seawater will help to propel
the seamen from the male into the female.
2. Female urogenital system:
The kidneys are flattened; ribbonlike, dark colored structures lying dorsally on either side of the midline,
along the entire length of pleuroperitoneal cavity. In female the upper portion of kidney is non-functional.
The female reproductive system begins in the ovaries. The ovaries are where the egg or ova is produced and
are located on the dorsal side of the shark, just next to the liver. Every egg yellow colored and is enveloped
in a follicle. The color is a result of the large amount of yolk in each ovum. From here, the ovum leaves the
14
15. Notes: Zoology- Semester VI, University of Mumbai, India
Presented by Prof. Sudesh D. Rathod
ovary, heading for the oviduct. The oviduct is a tube-like structure where the ovum is fertilized by the male
sperm. It is clearly visible in mature females due to its large size. The oviduct is connected directly to the
cloaca, allowing for sperm to pass directly to the ovum. Different areas of the oviduct have been shown to
perform different functions. One area of the oviduct that has been enlarged (distal to the ovaries) is knows as
the nidamental or shell gland. This gland has been shown to store sperm for great lengths of time to allow
for fertilization later. The oviduct thins out again, only to enlarge once more in a more caudal location to
form what is known as the uterus. The uterus is the location of embryonic development. The opening is
located towards the dorsal portion of the cloaca.
Copulation, fertilization and development
This shark is placentally viviparous, with arguably the most advanced reproductive mode of the
elasmobranchs. Male dogfish reach maturity at 11 years while female dogfish reach maturity at 19-20 years.
Eggs are ovulated at only 1 mm in diameter and the stalked placenta forms when the embryos are only a few
millimeters in length. The young are born at a length of 12-15 cm. Males mature at 24-36 cm and females at
33-35 cm. Breeding occurs throughout the year and females probably mate at least once each year.
Viviparous, with an unusual columnar placenta; litter size varies from 1 to 14. [Litter sizes range from 618, with a mean of 13.] The young are born throughout the year, after a gestation period of five or six
months.
Economic importance
Although dogfish liver oil was once valued for its vitamin A content and dogfish supported a thriving fishery
off Washington state and British Columbia, they are now rarely landed by North American fisheries.
However, substantial quantities are marketed for human food in Europe and Asia.
When abundant, dogfish may become a serious pest and inflict severe economic losses on fisheries by
damaging fishing gear and the catches of the more desirable fish. Furthermore, huge schools of dogfish
sweeping over the sea bottom devour and all but eliminate the smaller fishes and invertebrates in their paths.
Despite its commercial importance, overall fishery statistics for the spadenose shark are lacking. A 1996
report found it to be the most common coastal shark on Chinese markets, and it is also one of the most
common sharks caught off northern Australia. Substantial numbers are caught by Indian and Pakistani
fisheries; from 1979 to 1981, an average of 823 tons were caught annually off Verval, India. The spadenose
shark is also caught as bycatch, particularly in gillnet fisheries off Kalimantan.
Made by
Mr. S. D. Rathod
Associate Professor
Department of Zoology
B. N. Bandodkar College of Science
Thanr-400605
15