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Welcome to Zoo 511 Ecology of Fishes

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Welcome to Zoo 511 Ecology of Fishes

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  1. Welcome to Zoo 511Ecology of Fishes

  2. Today’s outline • Introductions • Review syllabus • Expectations and goals • Lecture – Fish Anatomy • Lab – fish dissections Bluegill Walleye

  3. Diversity of fishes

  4. “Take this fish and look at it.”

  5. What do you think: • What is a fish? • What could we learn from inspecting and dissecting a fish? (Think about what you learned already…)

  6. What is a Fish? • Poikilothermic – body temperature is identical to surrounding water • Chordates – have developmental characteristics of all vertebrates • Appendages developed as fins • Chief respiratory organs are gills • Body generally covered with scales “A fish is an aquatic vertebrate with gills and with limbs in the shape of fins” (Nelson 1994) There are >30,000 fish species, so there are exceptions to these general characteristics.

  7. Fish anatomy • Forms the basis for most identification • Anatomy can teach us about ecology & evolutionary relationships Mississippi paddlefish Porcupinefish Ocean sunfish Leafy seadragon

  8. Why dissect fish? • Evolution / phylogeny • Physiology • Pathology/disease • Gut contents • Otoliths (aging) • Fecundity/fitness

  9. Today’s Fish Goals • Practice skills of close observation • Learn basic external and internal anatomy of fishes • Practice using a dichotomous key to ID fish • Begin thinking about how structure relates to function Muskellunge Flounder

  10. Used for relating different parts….Eye is posterior to the mouth Anatomical terminology Dorsal Anterior Lateral Lateral Posterior or caudal Ventral Conversely the mouth is anterior to the eye

  11. External Anatomy Fins Mouth Scales Longnose gar (Lepisosteus osseus) White sucker (Catostomus commersonii) Sail fish (Istiophorus platypterus) River hatchetfish (Gasteropelecus sternicla ) Great white shark (Carcharodon carcharias) American eel (Anguilla rostrata)

  12. Adipose Fins Dorsal Caudal Pectoral Anal Pelvic Anal Pelvic Pectoral

  13. Caudal Fins

  14. Heterocercal • Tip of vertebral column turns upward • Epicercal: dorsal lobe larger (sturgeon) • Hypocercal: ventral lobe longer (flying fish) • Protocercal • Extends around vertebral column • Embryonic fish; hagfish • Diphycercal • 3 lobed; lungfish and coelacanth • Vertebral column extends to end of caudal fin, dividing into symmetrical parts • Homocercal • Vertebral column stops short of caudal fin, which is supported by bony rays • Symmetrical • Derived fishes

  15. Spines vs. rays Bluegill (Lepomismacrochirus)

  16. Spines • Rigid • Never segmented • Often for defense • Rays • Flexible • Often branched • Mainly for support Fisheries ecologists use both spines & rays for identification and aging!

  17. External Anatomy Fins Mouth Scales Longnose gar (Lepisosteus osseus) White sucker (Catostomus commersonii) Sail fish (Istiophorus platypterus) River hatchetfish (Gasteropelecus sternicla ) Great white shark (Carcharodon carcharias) American eel (Anguilla rostrata)

  18. Mouth placement superior terminal Inferior (sub-terminal)

  19. External Anatomy Fins Mouth Scales Longnose gar (Lepisosteus osseus) White sucker (Catostomus commersonii) Sail fish (Istiophorusplatypterus) River hatchetfish (Gasteropelecus sternicla ) Great white shark (Carcharodon carcharias) American eel (Anguilla rostrata)

  20. Scale types • Placoid • Ganoid • Cycloid • Ctenoid

  21. Placoid: sharks and rays “Riblets” decrease drag. Ganoid: bowfin, paddlefish, gar, sturgeon Armor-like plates for protection

  22. Cycloid and Ctenoid: most bony fishes (teleosts) • Overlapping = Flexibility, reduced drag • Both grow in concentric rings Cycloid: smooth outer edge, soft-rayed fish (e.g., salmon) Ctenoid: “toothed” outer edge, spiny fish (e.g., bass)

  23. Scutes are a modification of scales

  24. Modified placoid scales

  25. Snakehead Muskie Walleye FISH WITH TEETH Not all teeth are pointy! i.e. Vomerine teeth Chinook Salmon Burbot Longfinned Eel Pacu

  26. Gills and Gill Rakers

  27. Structure and function

  28. Barbels: nothing is easier to identify!! Yellow Bullhead Brown Bullhead Burbot Lake Sturgeon Burbot

  29. Lateral line • Sensory organ • Line of electroreceptor cells • Used to detect vibrations

  30. Premaxilla Dentary Maxilla

  31. Measure anatomy to do ecological studies

  32. Internal anatomy

  33. Kidney Stomach Swim bladder Liver Heart Intestine Ovary Fat deposits

  34. Red vs. white muscle • Red (aerobic) • High capillary density • Allows adequate oxygenation • Metabolizes lipids in mitochondria • White (anaerobic) • Converts glycogen to lactate • Lactic acid build up Cross-section of White Shark Caudal Peduncle

  35. Resources for Fish ID • Becker Key (ebook available) • WiscFish • FishBase (global)

  36. Get started! You need: A partner A fish Some tools The worksheet