Salmon Dissection Guide Alaska Department of Fish and Game

Salmon Dissection Guide Alaska Department Of Fish And Game-Free PDF

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SALMON INTRODUCTION,Have a discussion with students about showing. DISSECTION respect for all species This should serve as a. guiding principle for the students behavior during. the following activity,Provide each student with a copy of Handout 2 9. Part 1 Part 2 Salmon External Anatomy and,Handout 2 10 Salmon Internal Anatomy. Sketch an outline of a human on the chalkboard, Time Required Refer to the salmon handouts as needed to. 45 90 minutes explain the dissection Refer to the human sketch. to compare human physiology with fish,physiology If convenient you may prefer to.
Level of Conceptual Difficulty make overhead transparencies from the. Simple illustrations, Suggestions for Assessment If possible have teacher or adult volunteer assist. Monitor students responses during with any cutting required If students will be. using knives warn them to use caution If, the dissection Review their students are not doing the dissection have them. observations and ensure that they can their hands or optional skewers. identify and describe the basic parts, of a fish their functions and their This guide will follow the standard progression of. relationships to human physiology salmon dissection Instruction will cover first the. external outside features and then progress to,the internal inside organs Instructors may. Safety Warning choose to omit some dissection aspects. When working with sharp depending on students ages and scholastic. instruments safety guidelines should levels,be discussed with all participants This.
dissection is a guideline only and Advise students that if they feel uncomfortable. during the dissection they may look away or,individuals participate at their own. move their chairs farther back,risk To reduce risk it is. recommended that a teacher or adult Have students in pairs or individually use. volunteer monitor all facets of the Handout 2 8 Dissecting a Salmon to follow the. dissection dissection and record their information. Terms and Background Information,External Anatomy of the Fish. Head A salmon s head includes the eyes nostrils mouth and gills The area in front of the eyes. above the mouth is often referred to as the snout The position of the mouth varies among species. Fish absorb oxygen from the water The water is taken through the mouth flows over the gills and. then exits through the gill openings The gills are protected by a cover called the operculum Fish. have teeth in the jaws mouth and pharynx, Body The area immediately behind the operculum is called the pectoral or chest region The humeral. area or shoulders lies above the base of the pectoral fins The belly extends from the pectoral fins to. Tail The tail is the part of the fish behind the anus The slender section between the base of the. caudal fin and the anal or dorsal fin is called the caudal peduncle. Head Body Tail,External Anatomy Structures and Their Functions.
Eyes As with humans fish depend upon eyesight to see food avoid predators and to navigate. Because their eyes are bathed in water constantly fish do not have eyelids and do not need tears. Nostrils Salmon have a well developed sense of smell and use this ability to seek out their natal. streams The term natal stream refers to a salmon s water of origin Scent can also aid in avoiding. predators and finding food Fish breathe through their gills not their nostrils. Lateral Line Fish do not have ears as such In part low frequency sounds are detected in the water. through the lateral line a system of fluid filled sacks with hair like sensory apparatus that are open to. the water through a series of pores along each side of a fish The lateral line allows fish to detect. movement of other fish and predators in the water The full spectrum of frequencies fish can sense is. not completely understood There is some evidence the fish also sense medium frequencies. Mouth Fish use their mouths to catch food and hold food of various types but food is not chewed. before swallowing Salmon swallow food whole and the teeth are used for primary purpose of holding. prey that is struggling to escape In addition the mouth is a very important part of the breathing. process Water is constantly taken in through the mouth and forced over the gills. Gills Fish gills are composed of two basic parts the gill covers and the gills The gill covers protect. delicate gill respiratory apparatus and together with the mouth force water containing oxygen over. the gills The gills are delicate but effective breathing mechanisms and are one of the most important. organs of a fish s body Gills are far more efficient than human lungs because they can extract up to. 80 percent of the oxygen dissolved in water while human lungs only extract up to 25 percent of the. oxygen in the air, o Gills are thin walled structures filled with blood vessels The fish takes in water through its. mouth and oxygen dissolved in the water is absorbed through the thin membranes into the. fish s blood Carbon dioxide is simultaneously released from the blood into the water across the. same membrane This exchange is essential to the normal functions of the fish and contact with. the gills on a live fish should be avoided, o The gills have many blood vessels which accounts for their red color The lamellae or branches. of the gills perform the same function as the small sacs alveoli within human lungs They act. to transfer carbon dioxide from the body of the fish and absorb the oxygen from the water The. lamellae are only two cells thick and present maximum surface area to permit the most efficient. transmission of gases Under a lens the lamellae look like a Christmas tree. Fins Salmon have two sets of paired fins pelvic and pectoral and four single fins dorsal caudal. anal and adipose Except for the adipose and caudal fins the others are used basically to maneuver. and balance the fish in the water The adipose is a small fleshy fin which serves no known purpose. The most important fin is the caudal more commonly called the tail The caudal functions as a means. of propulsion In addition the caudal acts as a rudder The caudal fin is also used by female salmon to. dig the redd in which eggs are deposited, Scales The bodies of salmon are protected by scales which grow in regular concentric patterns and. can be used to determine the age and life history of the fish Covering the scales is a layer of mucous. slime which further protects the fish from diseases fungi and viruses The slime also helps fish slide. through the water more easily a term called hydrodynamics Slime also aids the fish in escaping from. Internal Anatomy Structures and Their Function, Ovaries The female reproductive organ ovaries produce eggs A group of eggs is often referred to as. a skein Eggs are often used for bait when sport fishing. Testis The male reproductive organ testis produce milt which contains salmon sperm. Liver The liver stores synthesizes and secretes essential nutrients that contained in food It destroys. old blood cells and maintains proper levels of blood chemicals and sugars The liver assists in digestion. by secreting enzymes that break down fats, Gall Bladder The gall bladder is a sac attached to the liver in which bile is stored and used to digest.
Heart Bony fish like salmon have a two chambered heart This muscular organ circulates blood. throughout the body and is part of the circulatory system. Esophagus The gullet or esophagus carries food from the mouth to the stomach. Stomach A sac like digestive organ receiving food from the esophagus and opening into the. Pyloric Caeca An appendage in the form of a blind sac connected with the alimentary canal in. which digestion takes place It also absorbs nutrients into the blood. Intestine The intestine extends from the pyloric caeca to the anal vent. Anal Vent Anal vent is also referred to as the anus This is where urine feces eggs and milt exit the. digestive system, Air Bladder Air bladder is also called the gas or swim bladder The air bladder is a membranous sac. filled with gas situated in the body cavity of fish ventral to the vertebral column which is used to. control buoyancy, Kidney These organs have multiple functions They remove waste from the blood and produce urine. Kidneys also aid in osmoregulation and production of red blood cells Osmoregulation is the ability to. control the concentration of substances in body fluids compared to the liquid outside of the fish. Spleen The organ in which white blood cells are produced and red blood cells are recycled The. spleen is also the storage location of blood for emergencies. Brain The control center of the nervous center, Otolith referred to as ear bone or ear stone These mostly calcium carbonate CaCO3 structures. help keep fish upright in the water column Growth rings formed in otoliths allow biologists to. determine the age of a fish,Dissection Preparation. Before the dissection begins prepare,all materials in a convenient area.
External Anatomy Features,Cover the dissection surface with. newspapers and then butcher paper Use handout 2 7 to identify the type. on top of the newspaper of Pacific salmon you have. Take time to consider the physical o King or Chinook salmon. arrangement of the room o Coho or Silver salmon,o Pink or Humpy salmon. Keep in mind that some students may o Chum or Dog salmon. not want to physically participate but o Sockeye or Red salmon. make it easy for them to participate,at their own comfort level. Make sure that you have adequate,volunteer support for the number of. participants,Talk to the volunteers and ask them,to encourage their students to.
discover the different parts but not to,remove any parts until they have had. a chance to discuss them,Slime Layer and Scales, What is the first thing you notice when you hold a fish. The fish is slippery,Many fish including salmon have a layer of slime. covering their bodies,The slime layer helps fish to. o Slip away from predators such as bears,o Slide easily through water.
o Protect it from disease fungi parasites and,pollutants that might be in the water It s a. living bandage that protects the salmon, What should you do to protect the slime coat on a fish that. What covers the fish s body under the slime layer, Small scales hard plates like fingernails that cover a. fish s whole body,Fish scale,The scales overlap to form flexible armor plating. that protects fish from predators and bruising,They start to reabsorb their scales when they.
spawn Scales aren t usually completely,reabsorbed at the time of death. The way scales are arranged in rows or patterns, is different for each species of fish You can tell. one species from another by the size of the,scales and the way they are arranged. Fish have the same number of scales all their lives. As fish grow the scales grow Along the way they, form lines like the rings in a tree Biologists can tell. the age of a fish and how many years it spent in, freshwater or saltwater from the lines on its scales.
If a fish loses a scale it can grow another to,replace it New scales have a clear focus. because they do not have the growth lines, Remove a scale and have students examine it later under a. hand lens or microscope,Fish Shape and Features,What shape is a fish What shape is a salmon. Why are fish shaped this way,Fish come in many shapes although torpedo. shape is the most common Salmon are torpedo, However some fish like flounder and halibut are flat.
Some are almost string like and a few are round like a. The streamlined shape of a fish lets it move easily. through water Water has much more resistance to,movement than air does so it takes much more. energy to move through water A streamlined shape,saves energy. What are the main parts of a salmon that you can,see on the outside. On the head you can see the mouth eyes and,On the body you can see the fins and tail the. vent and the lateral line,Fins and Tail,How many fins can you see How are they arranged.
Salmon have eight fins including the tail, Some fins are arranged in pairs one on each side of the. salmon s body, The pectoral fins are in the front below the shoulder. The pelvic or ventral fins are on the belly farther back. from the head, The others known as median fins are arranged in a line. on the salmon s belly and back,The dorsal fin is in the center of the back. The anal fin is in the center of the belly just in front of. The adipose fin is on the back in front of the tail The. adipose fin is sometimes clipped off in hatchery fish to. help identify the fish when they return or are caught. The tail is a special fin at the back of the body called. the caudal fin It includes the end of the backbone. What do the fins do,The fins have different functions.
The caudal fin or tail is the largest and most powerful. It pushes from side to side and moves the fish forward in. a wavy path, The dorsal fin acts like a keel on a ship It keeps the. fish upright and it also controls the direction in which. the fish moves, The anal fin also helps keep the fish stable and upright. The pectoral and pelvic fins are used for steering and for. balance They can also move the fish up and down in the. The adipose fin has no known function It does not, seem to harm salmon if it is cut off from nursery fish. Note that a fish uses its whole body to move through. Internal Anatomy for each student Writing supplies PREPARATION Before you begin Use Handout 2 7 to determine the species of salmon you are dissecting Option Some independent education suppliers education supply stores and science education catalogues carry cloth fish salmon anatomy puzzles 3 D models and posters that can help introduce this dissection activity to

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