Morphologie des poissons

1. Morphologie des poissons

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

13. Basic Anatomy Class Osteichthyes

14. 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

15. Basic Anatomybony fish

16. Internal Anatomy anus

17. Common Measurements

18. Basic Anatomy Coelacanth • Swim bladder modified to lungs • Paired appendages • Spiral valve intestine • Ureoosmoic strategy • Electric sense • Bony head • Scales and teeth • May have given rise to terrestrial tetrapods

19. 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)

20. 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.)

21. 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.

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

23. 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

24. 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

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

26. 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

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

28. 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

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

30. 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

31. 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

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

33. 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

34. 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

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

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

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

38. Fish Anatomy and Physiology

39. 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)

40. Sensory system Vision

41. Sensory system Olfaction • Locate prey • Find a mate • Migration

42. Sensory system Olfaction • Find a mate

43. Migration • Anadromous- salmon • can return to the same stream in which they hatched • may use land features, currents, salinity, temperature, the sun or magnetic field to get close to land • sense of smell • die after spawning • young return to the sea • 2. catadromous –freshwater eels • 3. Extensive migration-anatomical basis for magnetotaxis -- magnitite

44. Sensory system Lateral Line

45. Sensory system Electric sense Ampullae of Lorenzini pores • Detects weak magnetic fields produced by other fish • May also detect geomagnetic orientation

46. Sensory system Electric sense Paddlefish

47. Sensory system Electric sense knifefish

48. Sensory system Electric sense Electric ray Electric eel (really a knifefish)

49. Fish Locomotion

50. Types of Fins • The source of propulsion for virtually all fish comes from: • Undulation of the body • Paired Fins: • Pectoral • Pelvic • Unpaired Fins: • Caudal • Dorsal • Anal • A combination of the above