Lab Report on Shark free essay sample

As for the visual documentation of a living or dead specimen, digital photography has largely replaced traditional illustrations of the living specimen as the standard method of recording the colour and anatomy of the specimen in the field today. Earlier traditional illustration (coloured and black and white) are still considered scientifically important because they can stress fine anatomical features that are often obscured by liquid. Even today, these earlier traditional illustrations are referred in research and, in fact, are sometimes the only physical records of what a now-extinct (or near-extinct) fish look like in life. New technologies can only add to information we know about previously described species. Different kinds of animals have different body coverings. Marine vertebrates include 5 major groups based on observable features including body covering, among other characteristics: * Fish have skin covered with wet scales * Amphibians have bare skin that is usually moist or wet * Reptiles have skin covered with dry scales * Birds have skin covered with feathers * Mammals have skin covered with hair (fur) OBJECTIVES 1. Learn to use digital photography for visual documentation of specimen. 2. Locate and discuss the external and internal anatomy of the cartilaginous fish. 3. Draw and identify the external and internal features. 4. Describe the function for each feature. METHODOLOGY 1. The briefing on the experiment is given by the demonstrator. 2. The full images of the specimens and other important features are taken for identification purposes by using white slate board as the background. 3. Ruler is used as a scale. 4. A shark is dissected by the demonstrator. The external and internal features are identified. A summary on the digestive and the reproductive system of a shark is written. . The steps how to observe the internal anatomy of a stingray is told briefly by the demonstrator. 6. The steps that have been told are followed when observing the internal organ of the stingray. 7. The organs are observed and identified, and their physiological roles are discussed. 8. All the dissection materials are washed, the dissection pan is cleaned and dried and the lab is cleared from any fluid once complete. 9. The students’ hands are washed thoroughly. 10. A report which using only the materials from the practical is written. RESULTS Snouts Shark Caudal fin Posterior dorsal fin Scales Anterior dorsal fin Lateral Line Eye Spiracle External naris/ nostril Pelvic fin Cloacae Pectoral fin Mouth External gill slits Dissection of Bamboo shark Claspers Urogenital papilla Pancreas Spleen Duodenum Liver Stomach Duodenum Intestine Spleen Stomach Kidneys Kidneys Egg case Egg yolk Rectal gland Spiral valve Placoid scale of a shark EXTERNAL ORGANS ORGANS| FUNCTIONS| Mouth| The mouth used to take food and teeth in the mouth are used to hold and tear food rather than to chew it. Gills| The place where the gas exchange occurs which are the oxygenated water must always be flowing over the gill filaments for respiration to occur. | Nostril| Allow sharks to smell and detect chemical in water. | Eyes| To see the presence of preys. | Scales| Used for protection against predators and aid in swimming which have a hydrodynamic function. | Fins| The cartilaginous fins are used for the stabilization. | Snouts| Function as electro receptive organ, sensitive to electric charges of prey buried in the ground. | INTERNAL ORGANS ORGANS| FUNCTION| Liver| Act as the energy storage and to help keep the shark buoyant. | Oesophagus| Connects the mouth to the stomach. | Stomach| Food goes here after being consumed. Digestion takes place here. | Heart| To pump blood throughout the shark’s body. | Pancreas| Secrete the digestive enzyme. | Spleen| It acts as a salt gland, removing excess salt from the blood. | Ovary/ testes| Used in fertilization. | Intestine| Digestive tract just after the stomach. | Kidneys| Filter the excess water and excreted out the cloacae as urine. | Summary on the digestive and the reproductive system in sharks. The structures of the digestive tract are affected by many factors such as the type of food eaten, the level of activity and metabolism, and the size of the animal. The mouth and oral cavity of the shark has evolved according to the type of food the shark eats. Besides that, the shark tooth has evolved from a smooth round tooth to a sharp, serrated triangular tooth which is adapted to feeding on larger prey. Sharks have an expandable stomach to support this eating which is it can receive large quantities in one sitting. This large area for storage allows the shark’s metabolism to slow down, allowing it to not have to eat for long periods of time. This is important for any species that scours the open ocean, such as the oceanic white tip shark whose food is widely scattered and whose next meal is far from certain. Furthermore, in order to survive, a shark must eat 0. 6-3% of its body weight, each day. Indigestible things like very large bone and non-nutritive items, are vomited due to its valve (pyloric valve) can only enters liquid mush. All sharks have a relatively short gut, which is equipped internally with a special valve structure. The valve arrangement slows down the passage of food, allowing digestion to take place more effectively and nutrients to be absorbed more efficiently. In reproductive system in sharks, their eggs are fertilized inside the females body. The male shark has claspers, extensions of the pelvic fins that are used to transfer sperm to the female and fertilize her eggs. Most sharks give birth to live young, but some release eggs that hatch later. There are three types of sharks’ eggs development which are oviparous, viviparous and ovoviviparous. Oviparous are the sharks that deposit eggs in the ocean and will hatch later if they are not eaten by predators as the eggs are not guarded by their parents. Besides that, in viviparous sharks are give birth to live young which is the eggs hatch inside the females body and the babies are fed by a placenta which transfers nourishment from the mother to the babies. The sharks’ eggs that hatch and the babies develop inside the females body but there is no placenta to nourish the pups called ovoviviparous. The pups eat any unfertilized eggs and each other which is a form of sibling cannibalism. Stingray Caudal filament tail Cloaca Spiracle Barb Pelvic fin Gills Mouth Eye Snouts Liver Spleen Heart Kidneys Oesophagus Gill slits Brain Eggs Gall bladder Stomach Intestine Internal organs of stingrays (picture credited to hippocampus) DISCUSSION 1. Why are the spiracles important? Spiracles provide oxygenated blood directly to the eye and brain through a separate blood vessel which is reduced or absent in active, fast-swimming sharks. 2. What does the Lateral Line do? The lateral line system is very important in monitoring depth via atmospheric pressure, allows better hunting abilities which increasing the awareness of the location and movement of prey for the predator and for preys, it helps to keep the animal aware of possible dangers and allows for schooling behaviour. 3. How is the shark’s digestive system different from human? The digestive system in sharks and human are different in many aspects. Firstly, during the digestion in mouth, most sharks swallowed their large quantity food into their large stomach while human must do some physical digestion by chewing them into smaller pieces. Besides that, in stomach, sharks use very strong stomach acid to break down the food that has been swallowed, while human use lower acidity to break down the food as human has started the break down process starts from the mouth. Last but not least, the digestive system occurs in the intestine where in the sharks, it is called spiral valve. Their intestines are short but have a larger surface area due to the infolding of the inner surface while we have long intestinal tract with villi which increasing the surface area to absorb nutrients. 4. What is the largest single part of the nervous system? The largest single part of the nervous system in sharks is the brain. 5. What does optic lobe receive information from? The optic lobe receives information from the optic nerve which is from eyes. 6. What does the medulla oblongata and cerebellum control? Medulla oblongata is a region of the brain that controls many of the sharks spinal reflexes and homeostatic responses. The cerebellum is in charge of body movement which controls the muscular coordination and position of the sharks. 7. What are the differences between skates and rays? Use illustration to help you. SKATES| ASPECTS| RAYS| Rajiformers| ORDER| Myliobatiformers| Most have enlarge thorns along the midline of the back extending onto the tail| THORNS| No thorns along the midline back| Have two lobes| PELVIC FIN| Each pelvic fin has only one lobe| Stocky without a stinging barb and usually with two small dorsal fins near its tip| TAIL| Very slender and whip-like with a stinging spine midway along its length and usually without a dorsal.