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Chondrichthyes

Chondrichthyes . Chondrichthyes or cartilaginous fishes are jawed fish with: 1)paired fins 2) paired nares 3) scales 4) two-chambered hearts 5) skeletons made of cartilage rather than bone. The class is divided into two subclasses: 1) Elasmobranchii (sharks, rays and skates)

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Chondrichthyes

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  1. Chondrichthyes

  2. Chondrichthyes or cartilaginous fishes are jawed fish with: 1)paired fins 2) paired nares 3) scales 4) two-chambered hearts 5) skeletons made of cartilage rather than bone

  3. The class is divided into two subclasses: • 1) Elasmobranchii (sharks, rays and skates) •  2) Holocephali (chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class) Chimaera Rays

  4. SKELETON • - cartilaginous • - chondrichthyes lack ribs, so if they leave water, the larger species' own body weight crush their internal organs long before they suffocate.

  5. - red blood cells are produced in the: • 1) spleen and the epigonal organ (special tissue around the gonads) • 2) in the Leydig's organ which is only found in cartilaginous fishes, although some do not possess it

  6. APPENDAGES • - skin is covered with dermal teeth •     - In most species, all dermal denticles are oriented in one direction, making the skin feel very smooth if rubbed in one direction and very rough if rubbed in the other

  7. - One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion Heterocercal tail

  8. BODY COVERING • - Chondrichthyes have toothlike scales called denticles or placoid scales (provide protection, streamlining) Denticles

  9. - the old placoderms did not have teeth at all, but had sharp bony plates in their mouth - it is unknown which of the dermal or oral teeth evolved first

  10. RESPIRATORY SYSTEM • all breathe through 5-7 gills, depending on the species - a spiracle is a small hole found behind each eye and leads to the respiratory system (only found in cartilaginous fish and bony fish)

  11. BIOLOGY - Fertilization is internal- Development is usually live birth, but can be through eggs- There is no parental care after birth

  12. Resources • Biology Book: Miller, Kenneth. Chondrichthyes. Prentice Hall, 2003. Print. • Chondrichthyes. Web. 26 Apr 2011. <http://www.marinebiodiversity.ca>. “ fearbeneath.“ Web. 26 Apr 2011. <http://www.fearbeneath.com>. • “Chondrichthyes.“Wikipedia: The Free Encyclopedia.

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