What are fish? • Aquatic vertebrates • Most have • Paired fins • Scales • Gills • Wide range of characteristics • Belong to different classes
Fish Evolution • First fishes: armored bodies, no jaws • Cambrian period (510 mya) • 505 mya to 410 mya: Adaptive Radiation of fishes– variation increased (no armor v. armor; jaws v. jawless)
Fish Evolution • Jaw evolution and paired fins seem to have come about together • Made out of bone or cartilage • Paired fins • More control during swimming • Tail fins • More muscle mass along trunk of body
Fish Evolution • Fish evolved into two groups: • Class Chondrichthyes • Superclass Osteichthyes • Lobe finned (Class Sarcopterygii) • evolutionary links point to the lobe finned fish sharing a common ancestor with early amphibians • Ray finned (Class Actinopterygii)
Orders of Bony Fish • AnguilliformesOrder • SalmoniformesOrder • CypriniformesOrder • SiluriformesOrder • PerciformesOrder • Use your computers to research characteristics of one order (body layout, habitat, types of food eaten, modes of feeding, examples). • You will present your findings to the class.
Fish Order: • Body layout: • Habitat • Types of food eaten • Modes of feeding • Examples:
Fish Form and Function • Adaptations for life in water • Methods of feeding • Gills • Paired fins
Feeding • Display all modes of feeding • Herbivores, carnivores, omnivores, parasites, filter feeders, detritus feeders • Depending on type of food available • Some fish are highly specialized (barracuda - carnivore)
External Fish Anatomy • Fins: • Dorsal • Pectoral • Pelvic • Anal • Caudal
External Structures • Fins • steering, propulsion through water • Lateral Line • Operculum • covers/protects gills • Nares • Nasal openings
Lateral Line • Senses changes in the water • Current • Electrical • Heat • NO external ear • Utilizes lateral line for detecting sound vibrations
Key: External Fish Anatomy • Nares • Eye • Fins: • Dorsal • Pectoral • Pelvic • Anal • Caudal • Operculum • Mouth • Lateral Line
Skeletal System • Consists of bone and cartilage • Skull • Vertebrae • Ribs • Rays – within the fins
Muscular System • Tail and Trunk Muscle • Myotomes – blocks of muscle that run up and down the fish’s body • Separated by myosepta • Jaw • Fin
Digestive System • Mouth • Pharynx • Esophagus • Short, expandable (to enable swallowing of large food) • Stomach • Gastric glands • Pyloric ceca • Finger-like projections responsible for most digestion • Liver and pancreas • secrete enzymes to help with digestion • Intestines • majority of food absorption, length differs in herbivores a carnivores • Gizzard
Digestive System Labeling • Mouth • Pharynx • Esophagus • Liver • Gall bladder • Intestine • Anus • Stomach
Respiratory System • Gills on either side of the pharynx • Made up of filaments • Feathery structures with large number of capillaries for increased gas exchange • Pull water in through the mouth, over the gills, out the openings on the side of the pharynx
Specialized Respiratory Systems • Exception: Lungfish – need to go to surface of water to fill air sac (“lung”) • Oxygen poor water
Respiratory System • Afferent blood vessels • Efferent blood vessels • Gills • Operculum • Heart • Dorsal aorta • Ventral aorta
Also, describe how fish breathe. • What happens to the operculum? • What is the purpose of afferent/efferent blood vessels?
Nervous System • VERY simplified • Brain • 3 lobes • Forebrain (smell) • Midbrain (vision, learning, motor receptors) • Hindbrain (medulla oblongata and cerebellum) • Coordination • Movement • Balance • Spinal cord – serves rest of the body
Circulatory System • Closed circulatory system • Single loop around body • 4 part heart: (but considered 2 chambered) • Sinus venosus • Atrium • Ventricle • Bulbusarteriosus
Circulatory System – Blood Flow • Sinus venosusreceives unoxygenated blood from the body • Valve at the end of the sinus venosus opens into the atrium • Atriumhas thick, muscular walls • Atrium receives unoxygenated blood and pumps it into the ventricle • Ventricle is the largest and most muscular chamber of the heart • Ventricle fills with blood it constricts and forces the blood through the bulbusarteriosus
Circulatory System – Blood Flow • Bulbusarteriosusis a valve or series of valves that control blood flow out of the ventricle and into the ventral aorta. • Blood passes through the bulbusarteriosus to the ventral aorta. • From the ventral aorta, blood flows to the gill filaments, where it is oxygenated. • Blood flows out of gills through the dorsal aorta and through the fish’s body.
Label the heart of a fish • Sinus venosus • Atrium • Ventricle • Bulbusarteriosus • Vein • Ventral Aorta • Also, draw in direction of blood flow.
Circulatory System • Red blood cell production • Spleen • Kidney • Bones
Excretory System • Release nitrogenous waste as ammonia • Gills • Kidneys filter blood to excrete liquid waste • Kidneys allow fish to maintain salt balance • Salt water fish • Fresh water fish • Cloaca
Reproduction • External fertilization • Oviparous – completely separate from both parents • Females release eggs into water • Males release sperm • Ovoviviparous • One parent carries fertilized eggs until they hatch – no direct connection to the parent (yolk sac is nourishment) • Viviparous • Carry fertilized eggs internally – direct connection between mother and offspring (no yolk sac) • Live birth • Sharks
Growth and Development • Fish are able to live independently when hatched • Some species build nests, care for young for long periods of time • Aquatic life – minimal strain on organs, bone, muscle • Can grow large • Limits on circulatory system, brain function
Life Cycle of Bony Fish • Egg • Larval fish/Alevin • Fry • Juvenile • Adult • Spawning adult
Other Structures • Swim Bladder • Between the stomach and the spine • Allows for buoyancy • Fills with air to keep fish afloat • If the fish does not have a swim bladder, they will sink if they stop swimming
You will need to sketch and label the following systems: • External fish anatomy • Respiratory system • Reproductive system • Digestive system • Heart I expect these to be turned in with the dissection packet and questions.
Also… • You will be removing organs from your perch. • Throughout the dissection I will be circulating to see which organ(s) we will save for future comparisons. • You will be graded on the dissection as well as the post-dissection packet. • I will collect 1 packet from each person • The answers to the questions throughout the procedure should be on a separate sheet of paper – these can be completed after the dissection • Each group will receive a dissection grade.