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Sense Organs DR/ SOMIA Zaki
What’s Sense organ? A structure which is a receptor for external or internal stimulation. A sense organ is often referred to as a receptor organ. External stimuli affect the sensory structures which make up the general cutaneous surface of the body, the exteroceptive area, and the tissues of the body wall or the proprioceptive area. These somatic area receptors are known under the general term of exteroceptors. Internal stimuli which originate in various visceral organs such as the intestinal tract or heart affect the visceral sense organs or interoceptors.
A receptor structure is not necessarily an organ; in many unicellular animals it is a specialized structure within the organism. Receptors are named on the basis of the stimulus which affects them, permitting the organism to be sensitive to changes in its environment. Photoreceptors are structures which are sensitive to light and in some instances are also capable of perceiving form, that is, of forming images.
Light-sensitive structures include the stigma of phytomonads, photoreceptor cells of some annelids, pigment cup ocelli and retinal cells in certain asteroids, the eye-spot in many turbellarians, and the ocelli of arthropods. The compound eye of arthropods, mollusks, and chordates is capable of image formation and is also photosensitive. SeePhotoreception Phonoreceptors are structures which are capable of detecting vibratory motion or sound waves in the environment.
The most common phonoreceptor is the ear, which in the vertebrates has other functions in addition to sound perception. SeeEar Statoreceptors are structures concerned primarily with equilibration, such as the statocysts found throughout the various phyla of invertebrates and the inner ear or membranous labyrinth filled with fluid. The sense of smell is dependent upon the presence of olfactory neurons, called olfactoreceptors, in the olfactory epithelium of the nasal passages among the vertebrates. SeeOlfaction
The sense of taste is mediated by the taste buds, or gustatoreceptors. In most vertebrates these taste buds occur in the oral cavity, on the tongue, pharynx, and lining of the mouth; however, among certain species of fish, the body surface is supplied with taste buds as are the barbels of the catfish. SeeTasteThe surface skin of vertebrates contains numerous varied receptors associated with sensations of touch, pain, heat, and cold. SeeChemical senses, Cutaneous sensation, Sensatio
Types of sense Organs The Sense organs are cranial organs involved in special sensation, that is sensation other than general somatic or visceral sensation. The eye is the sensory organ of vision that gives rise to the fibers of the optic nerve. The olfactory epithelium is the sensory organ of taste that gives rise to the olfactory nerves. The taste buds of the Gustatory organ are innervated by the facial, glossopharyngeal and vagus nerves. The Ear, the sensory organ of hearing and balance, has an internal portion that is innervated by the vestibulocochlear nerve.
Sense organs in Amphioxus Animalia:Kingdom Phylum:Protochodata Subphylum:cephalochordate Order:Branchistoma Ex:Amphioxus
1-Amphioxus has an assortment of cells and organs for sensing light and mechanical stimuli. 2-amphioxus has auatomically simple but plausible homologs of both the pineal and paired eyes of vertebrates. 3- Amphioxus has olfactory system. 4-the variety of secondary sensory cell types that occur on the body surface in amphioxus, none are obvious homologs of vertebrate taste buds, neuromasts or acoustic hair cells.
5- A useful perspective can nevertheless be gained by examining differences in amphioxus. 6-specifically how each specifies and positions sensory precursors, controls their proliferation, and deploys them through the body. 7-The much larger size of vertebrate embryos and the need to cope developmentally with increased scale and cell numbers may account for some key vertebrate innovations, including placodes and neural crest.
8-The presence or absence of specific structural adaptations, like the latter, is therefore less useful for judging homology between amphioxus and vertebrates than shared features of specific cell types.
Sense organs in Petromyzon AnimaliaKingdom PhylumChordata VertebrataSubphylum CephalaspidomorphiClass PetromyzontiformesOrder PetromyzontidaeFamily Ex: Petromyzon
Olfactory organ in petromyzon In larval sea lampreys (Petromyzon marinus), a small, relatively inconspicuous olfactory organ sac contains small, densely packed olfactory receptor neurons and sustentacular cells.
Fish Classification AnimaliaKingdom ChordataPhylum Vertebrata Subphylum : class Agnatha 1- Chrondrichthyes 2- Osteichthyes 3- .
1)Class 1Agnatha(Hagfish) The Hagfish lacks true jaws or paired fins. The skeleton is cartliginous with gills in pouches (5 to 16 pairs). Heart 2-chambered. There are around 50 species.
-The morphology of electroreceptive organs in lampreys different fishes, aquatic amphibians, and monotreme mammals is described. -The sense organs vary from superficial end buds in lampreys, to ampullary organs and tuberous organs in many fishes and amphibians, to specialized mucous glands in the monotremes. -The sensory cells are quite different. Some have a bundle of apical microvilli, as in lampreys and many teleost fishes.
Shark Sensory Organs A shark relies completely on its sensory organs in all aspects of its life . One of the reasons sharks are extremely good predators is their amazing sensory ability . Their senses are remarkable like no other fish or mammal . Sharks rely on their complex sensory system in all aspects of their life, hunting, feeding, mating and general existence. HearingSmellLateral LinePit OrgansEyesightAmpullae of Lorenzini
Shark Sense of hearing Sharks also have an acute sense of hearing and can hear prey many miles away. A small opening on each side of their heads (not to be confused with the spiracle) leads directly into the inner ear through a thin channel. The lateral line shows a similar arrangement, as it is open to the environment via a series of openings called lateral line pores. In bony fishes and tetrapods the external opening into the inner ear has been lost.
Shark Sense of Smell Sharks have a keen sense of smell, with some species able to detect as little as one part per million of blood in seawater. They are attracted to the chemicals found in the guts of many species, and as a result often linger near or in sewage outlets. Some species, such as Nurse Sharks, have external barbels that greatly increase their ability to sense prey. The short duct between the front and back nasal openings are not fused together as in bony fishes. Sharks generally rely on their superior sense of smell to hunt prey, but at closer range they also use the lateral lines running along their sides to sense movement in the water, and also use special sensory pores on their heads (Ampullae of Lorenzini) to detect electrical fields created by prey.
Shark Lateral Line As in most fish, sharks also have a Lateral Line. This system is used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail. The receptors in the line, known as 'neuromasts', each consist of a group of hair cells. The neuromasts are usually at the bottom of a pit or groove, which is large enough to be visible. The hair cells in the lateral line are similar to the hair cells inside the vertebrate inner ear, indicating that the lateral line and the inner ear share a common origin. The development of the lateral-line system depends on the sharks mode of life. For instance, active swimming types tend to have more neuromasts in canals than on the surface, and the line will be further away from pectoral fins, presumably to reduce the 'noise' generated by fin motion.
Shark Face Sharks Are type of fishes with full cartilagenous skeletal and highly streanlined body.
