All Materials © Cmassengale
Fish
All Materials © Cmassengale
Kingdom
- Animalia
Phylum - Chordata
Subphylum - Vertebrata
Vertebrates:
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Include fish, amphibians, reptiles, birds, & mammals |
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Have a notochord (slim, flexible rod) present in early stages that may be replaced by backbone in adults |
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Contain a dorsal, hollow bundle of nerves called the nerve or spinal cord |
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Respire through pharyngeal or gill pouches during early development |
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Have post-anal tail in early stages |
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Endoskeleton made of bone &/or cartilage |
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Anterior head with well developed brain & sensory organs (Cephalization) |
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Closed circulatory system |
Taxonomy of Vertebrates:
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Agnatha include hagfish & lamprey with long, eel-like bodies without jaws or paired fins & cartilage skeletons |
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Chondrichthyes include sharks, rays, & skates with cartilage skeletons, paired fins, & jaws |
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Osteichthyes are bony fish with jaws, paired fins, & bone and cartilage in their skeletons |
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Amphibia include frogs, toads, & salamanders that go through an aquatic larval or tadpole stage |
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Reptilia include snakes, turtles, lizards, & alligators that live on land, are covered with scales, & lay a tough, protective amniote egg |
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Aves are birds covered with feathers, adapted for flying, & with hollow bones |
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Mammalia have hair or fur & females have mammary or milk-producing glands |
Evolution:
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Fossil record shows jawless fish without paired fins appeared first about 550 million years ago |
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Ostracoderm was a jawless, bottom-feeding ancestor to the agnathans (modern jawless fish) |
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Development of jaws & paired fins allowed better movement & increased ability to capture prey |
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Extinct acanthodians or spiny fish were first jawed fish with paired fins |
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Jaws probably developed from gill arches (bone that supports the pharynx) |
Characteristics of Fish:
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Streamlined body & muscular tail for swimming |
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Most with paired fins for maneuvering |
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Body covered with protective scales & mucus layer to reduce friction when swimming |
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Have less dense body tissues & store less dense lipids to help them float |
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Respire through gills |
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Most have a lateral line system or a row of sensory structures running down each side of the organism to detect changes in water temperature, pressure, current, etc. |
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Most with well-developed sense of sight & smell |
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Some can detect electrical currents |
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Ectotherms (adjust body temperature to environment) |
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Two chambered heart (upper atrium receives blood & lower ventricle pumps blood) |
Agnatha (Jawless Fish):
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Hagfish (live in oceans) & lampreys (found in marine & freshwater) |
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Circular mouths |
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Sharp teeth & strong rasp-like tongue to tear hole in prey & suck out blood & body fluids |
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Known as cyclostomes |
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Eel-shaped body |
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Mucus covers body |
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Skeleton made of cartilage |
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No paired fins |
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Gills without bony cover (called operculum) |
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Retain their notochord throughout their life |
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Hagfish are bottom dwellers in cold marine waters that burrow in mud, scavenge on dead & dying fish, & have tentacles around their mouth |
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Lampreys are usually parasites with a keen sense of smell to locate prey, lay their eggs in freshwater streams, & are covered with a poisonous slime |
Chondrichthyes
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Includes sharks, rays, & skates |
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Endoskeleton of cartilage |
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Hinged jaws & paired fins |
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Placoid scales & tooth-like dermal spines on scales |
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Marine |
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Carnivorous |
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Sharks are torpedo shaped |
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Rays & skates have broad, flat bodies with wing-like fins and a tail |
Shark Characteristics:
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Fast swimmers |
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Large, oily liver (20% of body weight) makes them buoyant |
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Tough, leathery skin |
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Fierce predators |
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Whale shark is largest & filter feeds on plankton |
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Ventral mouth with 6-20 rows of sharp, replaceable teeth |
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Short, straight intestine with spiral valve to slow food movement |
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5-7 pairs of gills for gas exchange |
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Kidneys remove wastes & maintain water balance |
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Electroreceptors on head help find prey & navigate |
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Lateral line along side of body contains sensory cells to detect vibrations & pressure |
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Separate sexes with external fertilization |
Ray & Skate Characteristics:
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Usually harmless to humans |
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Broad, wing-like pectoral fins used to glide through water |
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Flattened bodies with ventral mouth |
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Both eyes on top of head |
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Have protective coloration (darker on top & lighter on bottom) |
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Feed on fish & invertebrates |
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Stingray with poison spine by tip of tail |
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Electric ray gives off strong, electric shock |
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Manta ray is largest |
Traits of Bony Fish (Osteichthyes)
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Skeleton made of bone |
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Hinged jaws |
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Paired fins |
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Gills for gas exchange |
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Lateral line |
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Body covered with scales & mucus coating |
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Includes lobe-finned, ray-finned, and lung fish |
Lobe-finned Fish:
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Muscular, paddle-like fins supported by bone |
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Gills |
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Known as coelacanths |
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Thought to be extinct until 1938 when species found in Africa |
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Live in deep oceans |
Lungfish:
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Use lungs & gills |
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Eel-shaped body |
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Live in shallow, tropical rivers of Africa, Australia, & South America |
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Come to surface & gulp air when oxygen level is low |
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Form mud cocoon & become dormant if stream dries up |
Ray-finned Fish: 
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Fan-like fins supported by rays |
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Includes salmon, perch, catfish, tuna, etc. |
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Body covered with round, overlapping cycloid or ctenoid scales & mucus |
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Four sets of gills covered by bony operculum |
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Have movable fins |
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Dorsal fin(s) located on top keep fish upright & used for defense |
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Caudal fin or tail moves side to side to help steer |
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Pectoral fins (paired) on each side behind the operculum |
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Pelvic fins (paired) on ventral surface near the head |
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Anal fin (single) behind anus |
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Swim bladder is thin-walled sac in abdomen that creates buoyancy from diffusion of dissolved gas from blood |
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Kidneys filter the blood & help maintain water balance |
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Ectothermic - body temperature regulated by the environment |
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Keen sense of smell (nostrils) & have chemical receptors over the body |
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Can detect the earth's magnetic field as a guide to navigate oceans |
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Have separate sexes with external fertilization |
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Eggs hatch into fry |
Salmon
Life Cycle:
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Migrate up to 3200 kilometers following magnetic cues in the ocean |
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Follow mucus trails when navigating rivers |
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Return to birthplace to spawn |
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Males change color & jaw lengthens & develops a hook |
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Female uses her tail to build gravel nest & lays up to 10,000 eggs |
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Male deposits sperm over eggs |
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Adults usually die after spawning |
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Pacific salmon return to sea when 15 cm long; while Atlantic salmon may stay in river up to 7 years |
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Secrete mucus coating in river as return to sea |
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May stay in ocean 6 months to 5 years |
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