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The Craniates

The Craniates. Craniata Subphylum Hyperotreti- hagfish Subphylum Vertebrata- ostracoderms lamprey Gnasthostome fishes. Craniata. Skull made of cartilage or fibrous tissue Surrounds brain Olfactory organs Eyes Inner ear. Subphylum Hyperoptreti. Hagfish

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The Craniates

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  1. The Craniates Craniata Subphylum Hyperotreti- hagfish Subphylum Vertebrata- ostracoderms lamprey Gnasthostome fishes

  2. Craniata • Skull made of cartilage or fibrous tissue • Surrounds brain • Olfactory organs • Eyes • Inner ear

  3. Subphylum Hyperoptreti • Hagfish • Most primitive of all craniates • Brain • Bone Both brain and bone key elements in evolution

  4. Subphylum Vertebrata • The hyperoartia- • lamprey • Gnathostomata • Cartilaginous fishes • Bony fishes

  5. Survey of Fishes • Subphylum Hyperotreti- Hagfish • Subphylum Vertebrata- • Ostracoderms • Lampreys • Gnathostome Fishes

  6. Subphylum Hyperotreti • Class Myxini • Hagfish- • Heads supported by cartilaginous bars • Brains enclosed in fibrous sheath • Lack vertebrae • Retain notochord as axial support

  7. Four pairs of sensory tentacles surrounding mouths • Ventrolateral slime glands

  8. Coldwater marine habitats • Buried in sand and mud • Feed on soft bodied invertebrates • And scavenge on dying fish

  9. Subphylum Vertebrata • Vertebrae that serve as a primary axial support • Include Jawless ostacoderms and Hyperoartia (Lamprey) • Most part of a Superclass Gnathostomata • Include jawed fish and tetrapods

  10. Ostracoderms • Extinct agnathans • Bony armor • Bottom dwellers • Extracting annelids and other inverts from sediment • Bony plates around mouth- jaw like structure

  11. Hyperoartia • Class Cephalaspidomorphi • Lamprey (agnathas) • Marine and freshwater • Prey on other fish • Larvae filter feeders • Mouth is suckerlike • Epidermal teeth, rasping tongue • Glands secrete anticoagulant and feed on blood • External fertilization

  12. Gnathostomata • Jaws evolved from anterior gill support arches that had acquired a new role, being modified to pump water over the gills by opening and closing the mouth more effectively. • The mouth could then grow bigger and wider, making it possible to capture small prey. • This close and open mechanism would with time become stronger and tougher, being transformed into real jaws. • Modified dermal bones on the surface of the skin would migrate into the mouth and become primtive teeth.

  13. Paired appendages • Increased activity • Increased stability • Lateral steering • Pectoral fins- usually just behind the head • Pelvic fins- ventral and more posteriorly • Modern bony fishes pelvic fins usually behind the pectoral fins

  14. Ability to feed efficiently • Produced more offspring and exploit new habitat • Fostered adaptive radiation • Cartilaginous fishes • Class Chondrichthyes • Bony fish • Class Osteichthyes

  15. Class Chondrichthyes • Sharks • Skates • Rays • Ratfishes

  16. Most carnivores or scavengers • Marine • Biting mouthparts • Paired appendages • Placoid scales • Cartilagious endoskeleton

  17. Class Osteichthyes • Bone in their skeleton • and/or scales, • bony operculum covering gill openings and • lungs or swim bladder.

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