In the head region, the muscles do not exhibit any sign of segmentation and have become specialised to control the movement of the jaws, pharynx and eyes. According to Fairfax County Public Schools Ecology, the frog falls into the "amphibians" class because it can live in both water and on land. A large number of guanine plates are present on the inner surface of the choroid layer which is called tapetum lucidum. About this page Languages User feedbacks Citation Uploads Related species FishBase AdvertisementScoliodon laticaudus Müller & Henle, 1838Spadenose shark Like 0 You can sponsor this page Upload your photos and videos Add your observation in Fish Watcher | All pictures | Google image | | Native range | All suitable habitat | PointMap | Year 2050 | Scoliodon laticaudus … 6.14). After reading this article you will learn about: 1. On each side of the cloaca lies the abdominal pores. The dorsal root bears a ganglionic swelling. 6.2A). Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. (iii) A dorsolateral artery to the dorsal muscula­ture. The bursa entiana is immediately followed by wide tubular intes­tine which becomes narrowed posteriorly as the rectum. Muscular System 7. Many pores, called ampullary pores, are also present on the head. 2. c) Trilobed. Placoid scale has dual source of origin and develops partly from epidermis and partly from dermis. The egg of Scoliodon is strongly telolecithal. (f) A pair of iliac arteries extend to the pelvic fin as femoral arteries. Each egg gets a coating of albumen during its transit down the oviduct. The number of embryos present inside one uterus varies greatly in different species of Scoliodon. A pair of sacs designated as siphons are present. The fourth cranial nerve is called trochlear or pathetic nerve which arises from the dorso­lateral surface of the midbrain and supplies the superior oblique eye muscle. The testes are paired elongated organs (Fig. A small outgrowth often called ‘blind sac’ is present at the junction of the cardiac and pyloric limbs. In the trunk region, the muscles are greatly thickened on the dor­sal side on each side of the vertebral column, whereas in the tail region the muscles are equally developed round the vertebral column (see Fig. Venous System 15. 2 103 Mycology and Phytopathology . Physiology of digestion in Scoliodon. Two pectoral and two pelvic fins constitute the lateral paired fins. The body of the embryo is constricted from the blastodisc and the tail fold is differentiated and extended backward. 6.3). manoj kumar adaptations ADHATODA VASICA agarose agarose gel electrophoresis. The sinus venosus is a thin-walled tubular chamber. The sus­pension of the jaws with the cranium is made through the hyomandibular and this type of suspensorium is called hyostylic. The membranous labyrinth of Scoliodon performs three functions: (a) It helps in orientation in relation to gravity, (b) It accelerates in changing the direction during swimming and. The buccal cavity possesses no such glands that can be compared with the salivary glands of higher vertebrates. b) Bilobed. Along the anteroposterior direction the following arteries have their origin from the dorsal aorta: (a) Several buccal and vertebral arteries are given off anteriorly. Because of limited fecundity, the Scoliodon genus of sharks can be negatively affected by targeted fishing and habitat degradation. The trunk is more or less oval in transverse section. Name the ten Cranial Nerves found in Scoliodon Scoliodon laticaudus has a mirrorlike layer in the back of the eye, the tapetum lucidum. Enumerable pores on the dorsal and the ventral sides of the head lead into a long tube which terminates into radially arranged ampullary sacs (see Fig. Similarly a postorbital process emerges from the side forward along the upper margin of the orbit. The Scoliodon genus of sharks has been found mainly in the Indo-West Pacific oceans from the west coasts of Africa to South of Japan. A trunk ver­tebra has a centrum that encloses the notochord. The nervous system of Scoliodon includes: The central ner­vous system consists of brain and the spinal cord. 6.10). This system of veins returns blood from the head region and consist of a pair of internal jugular veins. Email This BlogThis! There are two blind sac-like olfactory organs situated in front of the mouth. Such contrac­tion is called the metachronal contraction. The respiratory organs are the gills which are borne by the gill-pouches. The midbrain is large and consists of two round optic lobes. Caudal fin is supported by the extensions of the neural and haemal spines. In the young stage the epithelial cells are ciliated. The iter (i.e., the communicating duct between the third and the fourth ventricles) is wider. The pectoral girdle is situated posterior to the last branchial arch and consists of two semicircular carti­lages united with one another along the mid-ventral line. Features of different phyla/ class are given below. The first visceral arch is the mandibular arch. C 45+5 4 3 hrs. It is claimed that during copulation the claspers are introduced into the cloacal aperture of the female for the transmission of spermatozoa. The abdominal cavity contains the viscera (Fig. The anterior and posterior cardinals unite on each side to form a transverse sinus called ductus Cuvieri. The terminal nerves are situated between the two olfactory lobes. The spine is composed of dentine coated externally with enamel. The movable pectoral fins lift the head upwards and this is compensated by the heterocercal tail. The sec­ond arch is called hyoid arch which consists of three parts—a ventral basihyal, a lateral ceratohyal and a dorsal hyomandibular. 6.14D). 3 104 Chemistry I They are invaginations of the ectoderm and do not communicate with the buccal cavity by an internal opening. It attains maximum thickness in the middle region and the body gradually tapers posteriorly into a long tail (Fig. The dorsal parietal artery supplies the dorsolateral musculature, the vertebral col­umn, the spinal cord and the dorsal fin. The pit organs occur on the lateral and dorsal sides of the head. Share to Twitter Share to Facebook Share to ... 2012 4TH LARVAL AND PUPAL STAGES. It discharges a fluid into the lumen of the intestine but its actual role is not known. Information and translations of Scoliodon in the most comprehensive dictionary definitions resource on the web. Short notes/sketch and label (4 marks each). The hyoidean epibranchial artery runs forwards and inwards to the posterior border of the orbit and gets an anterior branch from the dorsal aorta. (b) The auditory region is made of auditory capsules which remain firmly united with the cranium in an adult. As Scoliodon is viviparous the posterior portion of the oviduct becomes dilated to form the uterus for the development of the young. The dorsal side of Scoliodon is dark-grey while the under­side is pale white. In this article we will discuss about Scoliodon:- 1. (i) An ovarian (in females) or spermatic artery (in males) to gonad. Immediately after the entry to the cranium it joins with a branch from the internal carotid to form the cerebral artery. These nerves emerge from the telencephalon and bear a ganglion, called ganglion termi­nate, near the origin. In Scoliodon, the coelom is spacious and is divided into a smallest pericardial cavity and an extensive abdominal cavity. 6.18E). The sclera is cartilaginous. 6.14A). The species is abundant in Indian and Pakistani waters. The sec­ond pair of cranial nerves are the optic nerves which, after the origin from the optic thalami, form the optic chiasma and supply the eyes. Mouth: It is situated a little behind the apex on the ventral side of the anterior region of the body. The class Elasmobranchii embraces a large variety of cartilaginous fishes. In P.R. 6.2E). Fig. Each testis is attached to the dorsal body wall by peritoneal membrane called mesorchium and posteriorly attached by ordinary tissue with the caecal gland. (d) The anterior or the ethmoidal region of the cranium is composed of olfactory cap­sules and rostrum. Privacy Policy3. pp. Each half of this arch divides into two parts, the upper part is called palatopterygoquadrate which forms the upper jaw and the lower part is known as Meckel’s cartilage which forms the lower jaw. The dorsal fins are triangular in outline. All structured data from the file and property namespaces is available under the Creative Commons CC0 License; all unstructured text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. The posterior vertebrae contain haemal arch which is present on the ventral side of the centrum. Anteriorly the oviducts converge and open into the coelomic cavity by a longitudinal slit-­like opening designated as oviducal funnel. An occipital condyle is present on either side of the foramen magnum. Respiratory System 12. The third eyelid or nictitating membrane can cover the whole eye in emer­gency. It acts as reflector. (a) The occipital region forms the posterior portion of the skull and contains a large foramen magnum through which the spinal cord passes down. The radials at the distal ends contain small carti­lages bearing the ceratotrichia. It has been calculated that about 54 waves are produced per minute during steady swimming. The pharynx leads into a nar­row oesophagus. The utriculus together with the semicircular canals is responsible for the orientation and acce­leration, while the sacculus is meant for hea­ring. Each olfactory nerve is composed of many bundles of nerve fibres. The ventri­cle has a very thick muscular wall, the inner surface gives many muscular strands, thus giving it a spongy texture (Fig. A large number of small veins carrying blood from the alimen­tary canal and its associated glands unite to form the hepatic portal vein. Aedes. The lumen of the conus arteriosus is provided with two transverse rows of semi-lunar valves. At this stage an upper layer (epiblast) and a lower hypoblast is separated. There are five pairs of gill-pouches, each of which communicates with the pharyngeal cavity by a large internal branchial aperture and opens to the outside by exterior gill-slits (Fig. Name the types of nitrogenous bases present in the RNA. Scoliodon is a genus of requiem sharks in the family Carcharhinidae. It is covered by cartilaginous labyrinth. In addition to short longitudi­nal connectives connecting the four loops, these are further connected with each other by a network of longitudinal commissural vessels called the lateral hypobranchial chain. The eighth cranial nerve is called auditory which gives the vestibular and saccular branches to the inter­nal ear. This system comprises of two sets of veins—the anterior ventral veins pouring blood to the ductus Cuvieri through inferior jugular sinuses and the posterior veins which discharge through the subclavian vein. The inner surface of the intestine becomes folded to form an anticlockwise spiral of approximately two and a half turns. These eye muscles are attached with the eye ball in two groups. It consists of three semicircu­lar canals and a central body differentiated into an anterior utriculus and a ventral sacculus (see Fig. The first pair of cranial nerves are the olfactory nerves which originate from the olfactory lobes and inner­vate the olfactory sacs. Both sexes mature between 1-2 years old and the males reach largest size at the age of about 5 years and females reach largest size at the age of 6 years. This system is made up of a series of paired ganglia arranged irregularly on the dorsal wall of the kidney and the posterior cardinal sinuses. As the embryo elongates along the antero­posterior axis, a head fold is marked off from the blastodisc and it becomes raised up to form the neural folds. The median ventral fin is located in the mid-ventral line and just anterior to the caudal fin. The roof of the medulla oblongata is non-nervous and bears the posterior choroid plexus. With the expansion of the blastocoel the blastodisc becomes multi- layered. The cloaca opens to the exterior by a cloacal aper­ture which is located in between the two pelvic fins. The anterior rectus muscle runs out­wards and downwards and is attached to the ventral surface of the eye ball. The exter­nal carotid artery originates from the first col­lector loop and divides into a ventral mandibular artery giving branches to the mus­cles of the lower jaw and a superficial hyoid artery which supplies the second ventral con­strictor muscle, the skin and the subcutaneous tissue beneath the hyoid arch. (c) The middle region of the skull is composed of orbit. The mouth leads into a spacious buccal cavity which is lined with mucous membrane. Lata Fish: Systematic Position, Distribution and Structure, Nemertine: Characters, Structure and Sense Organs, Relationship between Swim-Bladder and Lung. The renal veins collect blood from the kidneys and unite to form the posterior cardinal sinuses. The function­al significance of the terminal nerve is not yet fully ascertained. The collecting tubules of the anterior non-renal portion of the kidney open to the Wolffian duct and the posterior tubules open into the ureter which in turn opens into the urinogenital sinus. The posterior region of the blastodisc grows faster than the other regions and is raised from the yolk mass to become a double- layered germ ring. Journal of Applied Ichthyology, 34(6), 1304–1313. 6.18D). Male Scoliodon species mature at a length of 33cm while female Scoli… 6.15 and 6.16). Two shallow depres­sions, called caudal pits, are regarded as the diagnostic features of the genus. Cobras are Elapids, a type of poisonous snake with hollow fangs fixed to the top jaw at the front of the mouth. Besides the eye muscles there are an optic nerve and a carti­laginous optic pedicle (Figs.
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