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Chondrichthyes

Chondrichthyes. Cartilaginous Fish. Characteristics. Endoskeleton entirely cartilaginous Fusiform Body Mouth Ventral Skin with placoid scales 2 chambered heart Separate exposed gill slits No operculum Heterocercal tail Internal reproduction (claspers & cloaca). Characteristics con ’ t.

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Chondrichthyes

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  1. Chondrichthyes Cartilaginous Fish

  2. Characteristics • Endoskeleton entirely cartilaginous • Fusiform Body • Mouth Ventral • Skin with placoid scales • 2 chambered heart • Separate exposed gill slits • No operculum • Heterocercal tail • Internal reproduction (claspers & cloaca)

  3. Characteristics con’t • No swimbladder or lung • 2 olfactory lobes • 2 cerebral hemispheres • 2 optic lobes • 1 cerebellum • 1 medulla oblongata • 3 pairs of semicircular canals • Ampullary organs of Lorenzini

  4. Fusiform body • Torpedo shape • Sharks have countershading (Dark on top & light on the bottom)

  5. Placoid Scales • These scales point towards the tail and helps to reduce friction from surrounding water when the shark swims

  6. Shark Anatomy

  7. Shark Anatomy

  8. Shark Senses smellhearinglateral line organ visionampullae of Lorenzinitouch and taste 

  9. Tapetum lucidum Reflects light in the eye

  10. How a Shark Eats

  11. Two chambered heart

  12. Gill Slits

  13. Lack operculum

  14. Heterocercal vs Homocercal • Sharks have heterocercal caudal fins with the vertebrae extending into the superior region of the caudal fin

  15. Shark Reproduction • Male claspers are inserted into female cloaca for internal fertilization • Ovoviviparous 90% • Viviparous (Great whites) • Oviparous

  16. Chondrichthyes Reproduction • oviparous (laying eggs that hatch outside the mother's body) • ovoviviparous (brooding eggs that hatch within the mother's body, and then releasing the young) • viviparous (young develop within a uterus inside the mother's body, and are nourished prior to birth via a connection with the mother's bloodstream (placenta).

  17. Female Reproductive Anatomy

  18. Male Reproductive Anatomy

  19. Cat Shark Egg Oviparous Porbeagle embryo viviparous Dogfish Shark embryos Ovoviviparous

  20. Swimbladder • Sharks lack a swimbladder • Oil in the liver is used to change buoyancy

  21. Lateral Line System

  22. Whale Shark Worlds largest fish (46 ft long)

  23. Not many fossils • Guitarfish (One of the few chondricthyes fossils)

  24. Elasmobranchii • Includes the familiar sharks, skates, and rays, as well as some strange fossil relatives. • Elasmobranchs have an upper jaw that is not fused to the braincase and separate slit-like gill openings.

  25. Rays & Skates

  26. Rays & Skates • Rays and Skates, unlike sharks, are not fusiform, but dorsoventrally flattened. • Gill slits open on the ventral surface of the head • Spiracles on the top of the head direct water over the gills, to prevent sludge from clogging these delicate structures • They feed primarily on mollusks and crustaceans, and so have teeth modified for crushing.

  27. Skates vs Rays • The major difference between skates and rays is the way in which they reproduce. • Rays are viviparous (live bearing) • Skates are oviparous (egg laying), releasing their eggs in rectangular cases sometimes called "mermaid´s purses".

  28. Mermaid purse

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