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Chapter 8

Chapter 8. Marine Fishes. Phylum Chordata. Subphylum Vertebrata. Classification of Fishes. Marine Fish. First vertebrates - 500 million years ago Oldest and largest group of vertebrates 24,000 known species of fish, 15,000 marine Bilateral symmetry Endoskeleton.

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Chapter 8

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  1. Chapter 8 Marine Fishes

  2. Phylum Chordata Subphylum Vertebrata

  3. Classification of Fishes

  4. Marine Fish • First vertebrates - 500 million years ago • Oldest and largest group of vertebrates • 24,000 known species of fish, 15,000 marine • Bilateral symmetry • Endoskeleton

  5. Vertebrates: An Introduction • Have a backbone (also called vertebral column or spine) • The backbone encloses and protects the nerve cord or spinal cord • The spinal cord ends in a brain protected by a skull

  6. Types of Marine Fish • Agnatha (jawless fish) • Hagfish • Lampreys • Chondrichthyes (cartilaginous fish) • Sharks • Skates • Rays • ratfish • Osteichthyes (bony fish) • Lobe-finned fishes • Ray-finned fishes

  7. Types of Marine Fish Class Agnatha(Hagfish and Lampreys) • Most primitive fishes living today • These jawless fish have a muscular, circular mouth with rows of teeth in rings and feed by suction • Long, cylindrical body • Lack paired fins and scales seen in other fish

  8. Types of Marine Fish A. Hagfishes or “slime eels” • 20 species • Exclusively marine • They feed on dead and dying fish and marine mammals • Live in burrows in soft sediments • Produce large quantities of mucous from glands in the skin to protect them while feeding

  9. Hagfish

  10. Hagfish video • http://www.youtube.com/watch?v=NYRr_MrjebA

  11. Types of Marine Fish B. Lamprey • 30 species • Freshwater (most) and Marine • Adults of some species live in sea, but return to freshwater to breed • Adults normally die after breeding. • Other species live in freshwater lakes • Attach to other fish and suck their blood

  12. Lamprey

  13. Lamprey • http://www.youtube.com/watch?v=x-KJZ22-wTQ

  14. Advanced Groups of Fish • Fishes in the Chondrichthyes and Osteichthyes are considered to be more advanced. • General Characteristics (advancements) seen in these groups: • Highly efficient gills • Scales cover the body • Paired fins • A wide variety of jaw and feeding types • Lateral line and other sensory organs • Streamlined body

  15. External Anatomy of More Advanced Fish Groups • These representative fish show the position of fins in cartilaginous and bony fish.

  16. Types of Marine Fish 2. Class Chondrichthyes – Cartilaginous fish • General Characteristics of Group: • About 1000 species • Sharks, rays, skates and ratfishes • Skeleton of cartilage -lighter and more flexible than bone • Movable jaws with well-developed teeth • Placoid scales and paired fins • scales cause rough, sandpaper skin • Spiracles in many species (openings on head used to bring water directly in for respiration without opening the mouth) • Males in most species have projections of the anal fin called claspers that are used in copulation

  17. Placoid scales Paired fins

  18. Class Chondrichthyes Sharks • 350 species well adapted for fast swimming (fusiform shape) and predatory feeding • Some have not changed for 100 my • Caudal fin (tail) well developed and powerful • Heterocercal – upper lobe longer than lower • Two dorsal fins and paired pectoral fins • 5-7 gill slits behind head on either side • Powerful jaws with several rows of teeth that move forward

  19. Shark Diversity

  20. Shark Diversity

  21. Class Chondrichthyes Shark Diversity – found in all oceans and depths • Hammerhead – wide flattened head acts as rudder and widens sensory organs for better reception • Sawsharks – long, flattened head with teeth • Thresher sharks – long upper lobe on tail to herd and stun fish • Spined pigmy shark – 10 inches • Whale shark – 60 feet filter feeders (plankton) • Great white shark – 20 feet http://www.youtube.com/watch?v=n9L4Mwn6wu0

  22. Class Chondrichthyes • Rays and Skates • 500 species • Dorsoventrally flattened • Demersal – bottom dwellers (some cover with sand and hide) • Pectoral fins flat and expanded – wings • 5 pairs of gills slits on ventral side • Spiracles on dorsal side

  23. Class Chondrichthyes • Rays • Large flattened teeth for feeding on molluscs and arthropods • Have long whip-like tails; in sting rays, there is a spine (barb) at the base of the tail with an associated poison gland • Stepping on a ray or making contact with the ray may eject venomous spine • Electric rays have organs that produce electricity on either side of head

  24. Types of Rays and Skates • Stingrays • Bat ray • Cow nosed ray • Electric rays • Eagle ray • Bull ray (killed Steve Irwin) • skates

  25. Cow nose ray

  26. Bat ray

  27. Eagle ray

  28. Bull ray

  29. Sting ray

  30. Ray and Skate Video • Stingray national geographic • http://www.youtube.com/watch?v=Nbuu1Fa-c1k

  31. Class Chondrichthyes • Skates • Dorsoventrally flattened with pectoral fins modified into wings • Rays are less mobile than skates • Skates have a fleshy tail and no spine on the tail • Major difference: • Rays are viviparous (bearing live young) • Skates are oviparous (laying eggs) • After fertilization, the female lays egg cases with an embryo inside • The embryo develops within the protection of the egg case for weeks to months • They are also demersal and feed on molluscs and arthropods primarily

  32. Mermaid’s Purse

  33. Class Chondrichthyes • Ratfishes (Chimaeras) • 30 species • Deep water inhabitant • One pair of gill slits is covered by a flap of skin • They feed on the bottom on crustaceans and molluscs primarily • Heterocercal tail like in sharks • Unlike others in this group, they also have fin rays (tiny support rods) in the fins

  34. Ratfishes or chimaeras Hydrolagus colliei

  35. Types of Marine Fish • Class Osteichthyes - The Bony Fish • Skeleton composed of bone • Over 23, 000 species worldwide • Gills used for respiration • Homocercal tail (two lobes of equal size) provides forward thrust • Cycloid (smooth) or ctenoid (spiny) scales • Operculum – boney flap protecting gills • Swim bladder – change depths (heavy skeleton)

  36. Swim Bladder • Swim bladder used for buoyancy control (some bottom dwelling fish lack swim bladder) • Sound, pressure detection • Bony fish ONLY- (ex. NOT in sharks)

  37. Biology of Fishes • Ichthyology – study of fishes • Body shape – related to lifestyle • Fusiform – streamlined, strong, fast • Compressed- thin, easy, quick short bursts • Depressed – flat, demersal, “fly” through water • Some irregular shapes can act as camouflage among seaweed, or rocks

  38. Coloration

  39. Biology of Fish - Coloration • Coloration • Cryptic coloration – color to blend in with environment • Bright colored – chromatophores • Structural colors – skin reflects only certain colors • Shiny iridescent fishes • Warning colors – advertise they are dangerous, poisonous, or taste bad • Disruptive coloration – stripes break up outline of fish • Difficult to pick out single fish from group • Countershading – light ventral and dark dorsal

  40. Cryptic Coloration

  41. Bright Coloration

  42. Structural Coloration

  43. Warning Colors

  44. Disruptive Coloration

  45. Biology of Fish - Locomotion • Most fish exhibit an “s-shaped” swimming pattern • Pushes against water to move body forward • Some move a) whole body, b) tail end, C) other fins, d) caudal fin • Myomeres – muscles run along sides of body

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