1 / 22

FISHES

FISHES. Fishes. All fishes retain four (4) primitive characters: Streamlined body Vertical tail fin Gills for gas exchange Lateral line system, No ears. Fishes. Three traditional vertebrate classes that remain aquatic. Class Bony Fishes Class Cartilaginous Fishes

Download Presentation

FISHES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. FISHES Fishes.ppt

  2. Fishes • All fishes retain four (4) primitive characters: • Streamlined body • Vertical tail fin • Gills for gas exchange • Lateral line system, • No ears Fishes.ppt

  3. Fishes • Three traditional vertebrate classes that remain aquatic. • Class Bony Fishes • Class Cartilaginous Fishes • Class Jawless Fishes • All three classes well adapted to aquatic environment. Fishes.ppt

  4. Class Bony Fishes • Also called “Ray-finned Fishes” • ~30,000 species. • Majority of living vertebrate species. • Bony skeleton, well developed skull • Fins supported by cartilage or bony “rays” and minute scales (=lepidotrichia) • paired fins: • pectoral, pelvic • median fins: • dorsal, anal, caudal Fishes.ppt

  5. Bony Fishes • Fins • paired fins: • pectoral, pelvic • median fins: • dorsal, anal, caudal Fishes.ppt

  6. Bony Fishes • Bony dermal scales • covered by thin epidermis • NOT homologous to reptilian scales. • Operculum covers gills; one gill slit each side. Fishes.ppt

  7. Bony Fishes • Lungs, often modified to swim bladder. • Examples: • sturgeons • gars • catfish • trout • bass • Northern pike • American eel • note paired fins, jaw, operculum Fishes.ppt

  8. Class Cartilaginous Fishes • 400 - 600 spp. • Skeleton of cartilage, bone lost. • Fossil placoderms and jawless fishes had bone tissue, prob. ancestral to both Cartilaginous & Bony fishes. Fishes.ppt

  9. Class Cartilaginous Fishes • Cartilaginous skull poorly developed, esp. dorsal to brain • Fins supported by cartilage or horn-like rays Fishes.ppt

  10. Cartilaginous Fishes • No ribs. • No lungs or swim bladder. • Separate gill slits, usually 5 • Placoid scales, • tiny, tooth-like • Enlarged at edge of mouth  teeth • Homologous to teeth in all other vertebrates. Fishes.ppt

  11. Cartilaginous Fishes • Sharks, • Rays • specialized flattened sharks • “wings” are pectoral fins Fishes.ppt

  12. Development of Jaws • All animals studied so far are “Jawed Vertebrates” • Jaws developed from gill arch, • Allowed diverse diet Fishes.ppt

  13. Class Jawless Fishes • Survivors of earliest vertebrates • No jaws, • can not close mouth • No scales • No paired fins, only median caudal fin (continues dorsal & ventral to anus) • Single median nostril on top of head • Circular gill slits • 7 or 12 pairs on sides of pharynx. Fishes.ppt

  14. Jawless Fishes • Hagfishes • tentacles around mouth • predators on worms, mollusks • scavengers • 20 spp. in 4 genera • Lampreys • circular mouth, no tentacles • filter feeders, or • external parasites of bony fishes • 30 spp. in 10 genera Fishes.ppt

  15. Jawless Fishes • Life cycle of sea lamprey • Adult parasitic, feeding stage • Adults swim into small freshwater streams to breed • Larvae live in sediment as filter feeders up to seven years • Metamorphosis, migration to lake or sea to become parasitic adults Fishes.ppt

  16. Jawless Fishes • Sea lamprey in the Great Lakes • Lake Ontario since end of last Ice Age, prevented from entering upper lakes • Welland canal • Sea lamprey devastated commercial fishing • Control Fishes.ppt

  17. Overview of where we have been • All animals studied to date belong to: • Phylum Chordata • notochord • dorsal nerve cord • pharyngeal arches/clefts • bear gills in fishes, • modified to other structures in terrestrial animals • postanal tail Fishes.ppt

  18. Review • Subphylum Vertebrata • Notochord reduced, replaced by bony or cartilaginous vertebrae • Some notochord tissue usually remains • Pharyngeal arches bear gills • or developed into other organs: hyoid bone, larynx • Liver • Pancreas Fishes.ppt

  19. Review • Subphylum Vertebrata • 7 traditional Classes: • Jawless fishes • Cartilaginous fishes • Bony fishes • Amphibians • Reptiles • Birds • Mammals Fishes.ppt

  20. Invertebrate Chordates • Two more subphyla of Chordata, lack distinguishing characters of Vertebrates: • Subphylum Urochordata • tunicates, sea squirts • Subphylum Cephalochordata • lancelets, amphioxus Fishes.ppt

  21. Subphylum Urochordata • Adult is sessile filter-feeder • Larva shows all characters of Phylum Chordata Fishes.ppt

  22. Subphylum Cephalochordata • Adult and larva show characters of Phylum Chordata • Live in holes in sandy or muddy bottoms • Ciliated pharynx pulls in water • Filtered water exits atriopore • Food directed to intestine , feces disposed through anus Fishes.ppt

More Related