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Phylum Chordata -Subphylum Vertebrata

Explore the unique characteristics, behaviors, and adaptations of jawless and cartilaginous fishes within the phylum Chordata. Learn about lamprey reproduction, parasitic tendencies, and the diverse features of Cartaliginous fishes.

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Phylum Chordata -Subphylum Vertebrata

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  1. Phylum Chordata-Subphylum Vertebrata Vertebrate Chordates

  2. General Characteristics 1. Vertebral column, or spine- bones or cartilage that surround and protect dorsal nerve cord

  3. 2. Cranium, or skull, to protect brain 3. Endoskeleton composed of bone or cartilage

  4. Class Agnatha • Greek, gnathus, meaning “jaws,” and a, meaning “without”

  5. Jawless fishes • Hagfishes and lampreys • Skin lacks plates and scales

  6. Eel-like body • Unpaired fins • Cartilaginous skeleton • Notochord remains

  7. Hagfishes • Small eyes beneath skin • Lack vertebrae • All species are marine

  8. Body fluids are isotonic to environment • Bottom dwellers in cold environments

  9. Feed on small inverts and dead or dying fish • Two plates and rough tonguelike structure pinch off chunks of flesh

  10. Often burrow into body of dead organism • Enter through gills, skin or anus. • Once inside, eat internal organs

  11. Secrete a bad-tasting, thick, viscous slime from skin gland to deter predators

  12. Knot-tying behavior • Clean excess slime • Stability and leverage to tear off food

  13. Yummy

  14. Lampreys • Most are anadromous • Adults move from ocean to freshwater • Opposite is catadromous

  15. Petromyzon marinus is most abundant (sea lamprey)

  16. Lamprey Reproduction 1. All breed in fresh water • Usually a shallow stream with a gravel bottom

  17. 2. Small nest is scraped out in gravel 3. Female and male simultaneously release eggs and sperm 4. Larvae resemble lancelets

  18. Larvae (ammocoetes) live in burrows in bottom of sandy streams as filter feeders (3-5yrs)

  19. Adults live in ocean for 1-2 yrs, spawn in fresh water, then die

  20. ~50% of species are parasitic • Feed on blood and body fluids of fish hosts • Hook-shaped teeth on oral disk

  21. Oral disk attaches to host • Rasping tongue scrapes hole in host • Anticoagulant released via saliva

  22. 4. Lamprey drops off - Host may recover, bleed to death, or die from an infection

  23. Infraphylum Gnathostomata

  24. Class Condrichthyes • Cartaliginous fishes • True jaws and teeth • Cartaliginous skeleton • Ampule of Lorenzini • Internal fertilization

  25. Sub-class Holocephalii • Ratfishes, chimeras • Fixed upper jaw • Scaleless • Deep water

  26. they are characterized by: • a gill cover over the four gills, leaving a single opening on each side of the head; • the palatoquadrate (upper jaw) is usually fused to the cranium; • no spiracle opening behind the eye; • branchial (gill) basket mostly beneath the neurocranium (posterior part of the cranium that encases the brain)

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