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Cartilaginous Fishes

Cartilaginous Fishes. Cartilaginous fishes ( Chondrichthyes) have a skeleton made not of bone, but of cartilage , which is lighter and more flexible than bone Cartilaginous fishes have well-developed jaws and paired fins for efficient swimming

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Cartilaginous Fishes

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  1. Cartilaginous Fishes • Cartilaginous fishes (Chondrichthyes) have a skeleton made not of bone, but of cartilage, which is lighter and more flexible than bone • Cartilaginous fishes have well-developed jaws and paired fins for efficient swimming • Most cartilaginous fish also have rough, sandpaper-like skin, the result of placoid scales pointed tip directed backwards

  2. Cartilaginous Fishes • Cartilaginous fishes include sharks, skates, rays and chimeras, or ratfishes • Nearly all are marine • ~350 species of sharks; ~500 species of skates and rays; 30 species of chimeras

  3. Sharks (cue scary, cello music) • Sharks are often referred to as living fossils because many of the species alive today are similar to ones that swam the seas >100 million years ago • Sharks have powerful jaws with rows of numerous sharp, often triangular teeth • Lost or broken teeth are quickly replaced by another, which shifts forward from the row behind it as if on a conveyor belt http://www.evolutionnyc.com//ImgUpload/P_455917_964647.jpg

  4. Sharks • Sharks have fusiform, spindle-shaped bodies, which cut easily through the water • A well-developed, muscular caudal fin propels them through the water; paired pectoral fins enable steering and dorsal fins provide stability

  5. Sharks are efficient predators • Many sharks exhibit counter-shading, appearing dark on top and light on the bottom • Camouflage from above and below • Why? flmnh.ufl.edu

  6. Rays and Skates • Rays and skates have dorsoventrally flattened bodies, with 5 pairs of gill slits on the underside (ventral side) of their body • Most are demersal, spending much of their lives on the sea floor • Pectoral fins are greatly extended resembling wings

  7. Is it a ray, or a skate? • Skates usually have 2 dorsal fins; Rays lack dorsal fins altogether • Skates have a muscular tail; Rays have a whip-like tail, usually with a prominent stinger Ray Skate

  8. Chimeras, or ratfishes • Approximately 30 species of deep-water, strange-looking cartilaginous fish are grouped separately as chimeras, or “ratfishes” • Only one pair of gill slits, covered by a flap of skin • Demersal (bottom-dwelling) • Some with a long, rat-like tail

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