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Fish Morphology

008b. Fish Morphology. Classification Scheme of the Vertebrates. Phylum Chordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Class Amphibia Class Reptilia Class Aves Class Mammalia. Chordate Characteristics. Chondrichthyes (370). Placoderm

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Fish Morphology

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  1. 008b Fish Morphology

  2. Classification Scheme of the Vertebrates Phylum Chordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Class Amphibia Class Reptilia Class Aves Class Mammalia

  3. Chordate Characteristics

  4. Chondrichthyes (370) Placoderm (395-345) Ostracoderm (510-=350 mybp) (360) Osteichthyes (395) lamprey & hagfish

  5. Jaw Development agnathostome gnathostome 1st appeared 400 mya

  6. Basic Anatomy Class Agnatha • Possess medial nostril, medial fins, notocord rather than vertebral column • 7 or more pr gill pouches present • Light sensitive pineal eye • Fertilization external • Cartilaginous skeleton • Lack jaws, paired fins, scales • GI track w/out stomach • Lampreys and hagfish • 100 species

  7. Class Agnatha Lamprey ammocoetes

  8. Class Agnatha Hagfish

  9. Basic Anatomy Class Chondrichthyes Sharks, skates, rays

  10. Basic Anatomy Class Chondrichthyes Sharks, skates, rays • Posses jaws with teeth, cartilaginous skeleton, paired fins • Scales (denticles) have same origin and composition as teeth • Possesses 5-7 gills • Spiral valve intestine • Ureoosmotic strategy • Electroreception • Lateral line • No swim bladder • Heterocercal tail • Relatively unchanged (480 mybp)

  11. Basic Anatomy

  12. Basic Anatomy Class Osteichthyes

  13. Basic Anatomy Class Osteichthyes • Posses jaws with teeth, bony skeleton, paired fins • 4 paired gill arches covered by operculum • Intestine- simple, no spiral valve • Swim bladder • Lateral line • Homocercal tail • Scales- cycloid, ctenoid

  14. Basic Anatomybony fish

  15. Internal Anatomy anus

  16. Common Measurements

  17. Basic Anatomy Coelacanth Latimeria • Swim bladder modified to lungs • Paired appendages • May have given rise to terrestrial tetrapods • Bony head • Scales and teeth

  18. Coelacanth Thought to be extinct 80 million years ago Found in 1938 off the coast of the Comoro Islands

  19. Who found it first? 1938 Marjorie Courtenay-Latimer

  20. Where was it found?

  21. J.L.B. Smith, Rhodes Univ., Grahamstown

  22. Coelacanth Anatomy • Fins: • 2 dorsals • 2 pectorals • 2 pelvics • 1 anal • 1 caudal

  23. Coelacanth Anatomy Unsegmented notochord Rostral organ Intercranial joint Fat filled swim bladder Ovoviviparous

  24. Anatomical comparison between Sarcopterygian, amphibian, and reptile.

  25. Anatomical Similarities to Sharks: Spiral valve intestine Give birth to live young Long cartilaginous tube instead of backbone Osmoregulatory strategy Anatomical Similarities to Fish: bony head teeth scales

  26. Anatomical Similarities to Tetrapods: • fat filled lung • fleshy lobed-fins • circulatory system • inner ear • tooth enamel • intracranial joint- a feature once found in ancient frogs The coelacanth’s phylogenetic classification remains inconclusive

  27. Fish Adaptations and Life Styles • General Life Style Categories • a. pelagic cruisers • occurring in water column far away from the bottom (benthic) environment • often referred to as "blue water" • includes tuna, billfish, blue sharks, mackerel sharks (great whites and mako sharks)

  28. b. demersal • bottom-associated fishes, but not usually sitting on the bottom • rely on the benthic environment as a source of food, place to reproduce, and/or place of refuge, etc. • includes most reef fishes (e.g., butterfly fishes, surgeon fishes, wrasses, parrot fishes, etc.)

  29. c. benthic • bottom-dwelling fishes that spend the majority of time sitting on the bottom • includes flatfishes, lizard fishes, many scorpion fishes, many hawkfishes, gobies, etc.

  30. Body shape 1) fusiforma) = torpedo-shaped b) allows minimal drag while swimmingc) best shape for a pelagic cruise tuna

  31. 2) compressed • laterally flattened (e.g., butterflyfishes & surgeonfishes) • allows for maneuverability in surge environments • useful for demersal fishes that hover above the reef • exception seen in flatfishes that lie on one side of the body as benthic fishes

  32. 3) elongated or attenuated • long body (e.g., trumpetfish, cornetfish, eels) • seen in demersal fish that either hover motionless in the water) • seen also in benthic fishes (e.g., eels) that hide in holes in the reef

  33. 4) depressed • dorso-ventrally flattened (e.g., frogfishes, scorpionfishes & gobies) • broad ventral surface facilitates resting on the bottom • seen in many benthic fishes

  34. Body Coloration • 1) source of color • pigment color - chromatophores for yellows, reds, oranges, browns, & blacks • structural color - iridophores (reflection) & light refraction for blues, silvers, & rainbows

  35. 2) patterns • a) countershading • dark blue or black dorsally, white or silvery ventrally • results in blue water "camouflage“ • observed most frequently in pelagic cruisers

  36. b) camouflage • matching the background coloration • usually involves having irregular dark blotches and spots • typically seen in benthic fishes, especially benthic ambush predators (e.g., frogfishes, gobies, & many scorpionfishes) • some fishes (e.g., flatfishes) may exhibit rapid color changes in response to different backgrounds

  37. b) camouflage • 5) matching downwelling light Hatchet fish Cookie cutter shark

  38. c) disruptive coloration 1) color pattern breaks up the silhouette of the fish 2) may involve dark bars across the eye and tail region 3) seen in many demersal fishes such as butterfly fishes

  39. d) bars and stripes 1) bars are vertical (e.g., manini) 2) stripes are horizontal (e.g., ta'ape) 3) seen frequently in schooling demersal fishes 4) may confuse potential predators by making it difficult to select individual prey from the school

  40. e) misdirection 1) false eye spots, etc. 2) observed in many demersal butterfly fishes

  41. f) advertising coloration 1) bright, obvious color patterns 2) possible functions a) advertising a cleaning station (e.g., cleaner wrasses) b) advertising a warning (e.g., nohu) c) advertising for mates (e.g., male parrotfishes) Hawaiian cleaner wrasse Nohu

  42. g) mimicry 1) imitating other creatures 2) seen in a few demersal and benthic fishes 3) examples a) blenny (Aspidontus taeniatus) mimics cleaner wrasses b) shortnose wrasse mimics Potter's angel which sports a defensive spine

  43. g) mimicry 4) leafy sea dragon (Australia)

  44. h) uniform red coloration • most often observed in deep-dwelling or night active demersal fishes • examples include opakapaka, oweoweo, menpachi, & squirrelfishes

  45. i) noctural versus diurnal color changes j) male versus female color differences k) juvenile versus adult color differences Dragon wrasse Stoplight parrotfish Bluehead wrasse

  46. Fish Anatomy and Physiology

  47. Sensory system • vision • hearing – inner ear; swim bladder amplifies in some fish • olfaction –  olfactory sacs; taste buds • lateral lines of fish – detect vibrations in the water • Electrical Sense: ampullae of Lorenzini (sharks and rays) – sensitive to electric currents • geomagnetic sensory system (long distance migration- tuna)

  48. Sensory system Vision

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