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Fishes. Chapter 11 Section 2. Characteristics of Fishes. Vertebrate Lives in the water Uses fins to move Ectotherms Obtain oxygen through gills Have scales . Obtaining Oxygen. Fishes get oxygen from the water Fish gulps water (water contains oxygen)
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Fishes Chapter 11 Section 2
Characteristics of Fishes • Vertebrate • Lives in the water • Uses fins to move • Ectotherms • Obtain oxygen through gills • Have scales
Obtaining Oxygen • Fishes get oxygen from the water • Fish gulps water (water contains oxygen) • Moves through openings in fish’s throat to the gills • Water flows over gills • Oxygen moves from water into the fish’s blood
Circulatory System • Closed circulatory system • Heart has two chambers, or inner spaces • Pumps blood in one loop • Heart to the gills • Gills to rest of the body • Back to heart
Movement • Fins help fish swim • Thin membrane stretched across bony supports • Fin provides large surface to push against the water (canoe paddle) • Movement is related to obtaining food and reproduction
Reproduction • External fertilization: the eggs are fertilized outside the female’s body • Male hovers close to female and spreads a cloud of sperm cells over the eggs • Internal fertilization: giving birth to live young • Sharks • Guppies
Nervous System • Nervous system and sense organs of fishes help them find food and void predators • Keen sense or touch, smell, and taste help fishes capture food
Major Groups of Fishes • Jawless • Cartilaginous • Bony
Jawless Fishes • No jaws or scales • Have mouths instead (scraping, stabbing, and sucking their food) • Cartilage: tissue that is more flexible than bone • Examples • Hagfish • Look like large, slimy worms • Lampreys • Can be parasites • Use sharp teeth and suction cup mouths to feed on other fishes • Eel-shaped bodies
Cartilaginous Fishes • Have jaws and scales, and skeletons made of cartilage • Most sharks cannot pump water over their gills, rely on swimming or currents to keep water moving across gills • Rays and skate take in water through small holes located behind their eyes • Usually carnivores • Sharks: attack and eat nearly anything that smells like food, many rows of teeth • Rays and skates: hunt on ocean floor, crushing mollusks, crustaceans, and small fishes with their teeth
Bony Fishes • Examples: trout, tuna, goldfish • Have jaws, scales, a pocket on each side of the head that holds the gills, and a skeleton made of hard bones • Fins: help the fish stay upright • Scales: cover the body by overlapping each other • Gill Pocket: holds the gills • Swim Bladder: helps stabilize the fish at different depths in the water