Fishes

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Fishes

  1. 1. • Animals that have a Chordates backbone are called vertebrates.• Vertebrates belong to phylum chordata (called chordates)• Vertebrates make up largest group of chordates
  2. 2. •Two other groups of chordates arelancelets and tunicates •Much simpler than vertebrates (no backbone or well developed head)
  3. 3. Chordate Characteristics• 1) Have a tail (some only have a tail during embryo stage)• 2) Hollow nerve cord —in vertebrates it is called spinal cord• 3) Pharyngeal pouch —develop into gills or other body parts as embryo matures• 4) Notocord —stiff but flexible rod that gives body support – In most vertebrates, embryo’s notocord is replaced by a backbone
  4. 4. Vertebrate Characteristics– Have a backbone (strong but flexible column of bones called vertebrae)– Have well developed head protected by skull (made of bone or cartilage) • Cartilage is tough material that flexible parts of ears and nose are made of– Skeletons of vertebrate embryos are cartilage and harden into bone
  5. 5. Are Vertebrates Warm or Cold?• Birds and mammals are endotherms (warm blooded) – Use energy released by chemical reactions in the body to stay warm
  6. 6. • Fish, amphibians, and reptiles are ectotherms (cold blooded) – Depend on their surroundings to stay warm
  7. 7. Fish Characteristics• More than 25,000 species of fish• All fishes share several characteristics: – (1) Born to swim • use fins to steer, stop, and balance • scales are bony structures that cover and protect body and lower friction
  8. 8. – (2) Making Sense of the World • have senses of vision, hearing, and smell • have a lateral line system (row of sense organs that detect water vibrations)– (3)Underwater Breathing • use gills to breathe (organ that removes oxygen from water) • gills also remove carbon dioxide from the blood
  9. 9. – (4) Making More Fish • most fish reproduce by external fertilization • females lay eggs in water and male drops sperm on them
  10. 10. Kinds of Fishes• Three classes of fishes still living today: – (1) Jawless fishes • first fishes (have been around for half a billion years) • Two kinds: hagfish and lampreys • Smooth, slimy skin and round, jawless mouth • No backbone, but does by a skull, brain, and eyes
  11. 11. Cartilaginous Fishes– (2) Cartilaginous Fishes • skeleton never changes to bone; stays cartilage • have fully functional jaws • strong swimmers and expert predators • excellent senses of sight and smell • to stay afloat, they store a lot of oil in their liver, which helps them be buoyant • Examples: skates, stingray, sharks
  12. 12. Bony Fishes– (3) Bony Fishes • largest class of fish (95% of all fishes are bony fishes) • very different from other fishes—skeleton made of bone and body covered by bony scales • Unlike other fishes, they can rest in one place without swimming because they have a swim bladder (gas-filled sac that helps fish be more buoyant)
  13. 13. • Two main groups: ray-finned and lobe-finned – Ray finned: eels, herrings, trout, minnows, perch – Lobe finned: lungfishes
  14. 14. Hagfish:jawlessShark:cartilaginousTrout:bony
  15. 15. Stingray: cartilaginousLungfish: bonyLamprey: jawless

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