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Fishes

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Fishes

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  1. Fishes Chapter 39

  2. Introduction to Vertebrates Section 39.1

  3. Vertebrate Characteristics • Only 1 phylum: Chordata • Three distinguishing characteristics: • Vertebrae: bones or cartilage that surrounds and protects dorsal nerve cord (spine) • Cranium: skull that protects the brain • Endoskeletoncomposed of bone or cartilage

  4. Vertebrate Classification • Nine Classes: • Hagfishes: elongated, eel-like bodies, lack jaws, no paired fins, no vertebrae (have notochord) • Lamprey:same as hagfish except they have a primitive vertebrae • Sharks, Rays, & Skates: jaws, paired fins, cartilage skeleton • Ray-finned Fish:jaws, bony skeleton,

  5. Classification Continued 5. Lobed-finned Fish: fins on main axis of body 6. Amphibians:thin & permeable skin, eggs & larval stage in water 7. Reptiles:dry & scaly skin, eggs on land 8. Birds:flight, feathers, hollow bones, unique respiratory system 9. Mammals: hair, mammary glands

  6. Vertebrate Evolution • 560 million years ago • First vertebrae = tadpole like, jawless fish

  7. Origin of Jaws • 450 million years ago • Evolved from first pair of gill arches: • skeletal elements that protect pharynx • Jaws aid in food seizure and manipulation

  8. Scientific Names: • Hagfish • Class Myxini • Lamprey • Class Cephalaspidomorphi • Sharks, Rays & Skates – Class Chondrichthyes • Ray-Finned Fish • Class Actinopterygii • Lobed-Finned Fish • Class Sarcopterygii

  9. Amphibians • Class Amphibia • Reptiles • Class Reptilia • Birds • Class Aves • Mammals • Class Mammalia

  10. Jawless & Cartilaginous Fishes Section 39.2

  11. Fish Characteristics for the Water: • Streamline body shape • Strong muscular tail for propulsion • Paired fins to maneuver in multiple directions • Secreted mucus to reduce friction • Stored fat to help float • Gills for respiration

  12. FishHomeostasis • Maintain homeostasis through osmosis • osmoregulation • Waste removal organs: kidneys & gills • Kidneys filter wastes from blood & removes excess water as urine • Out through the cloaca • Gills remove waste gases (CO2) and excess ions directly into the water

  13. Fish Sensory Functions • Advanced senses to detect light, chemicals, sound, electrical and magnetic fields • Chemoreception: detect chemicals in the form of smell and taste • Lateral line system: • Row of sensory structures that run the length of the fish’s body on each side • Connected by nerves to the brain • Detects vibrations in water

  14. Jawless Fishes Video • Hagfish (Class Myxini): • Bottom dwellers, marine habitat • No vertebrae (have notochord) • Mouth with two movable plates & rough tongue-like structure • Burrow into body eat from the inside out • Lamprey (Class Cephalaspidomorphi) : • Some are parasitic on other fish • Disk-shaped mouth with rough tongue that scrapes a hole into host Video

  15. Cartilaginous Fishes • Class Chondrichthyes • Examples: Sharks, rays, & skates • Skeletons made of cartilage: • Flexible, lightweight material made of cells surrounded by tough fibers of protein • Carnivores • Skin covered with placoid scales: • Small, tooth-like spines that feel like sandpaper

  16. Adaptations • Gills for respiration • Fast swimming or pumping water over gills • Rays & skates have spiracles to draw in water • Rectal gland: end of intestine that removes excess ions from the blood and releases into rectum for elimination • LARGE liver stores lipids to maintain buoyancy

  17. Reproduction • Internal fertilization • Male inject sperm into female with modified pelvic fins called claspers • Many cartilage fish have live birth • No parental care once born

  18. Rays & Skates • Flattened bodies • Wing-like pectoral fins • Bottom dwellers • Most feed on mollusks and crustaceans Video

  19. Sharks Video • Pectoral fins:just behind head, jut out from body like wings of a plane • 20,000 teeth during lifetime! • Multiple rows • Olfactory bulbs: part of brain that detect smells from paired nostrils • Fusiform: smooth, torpedo-shaped bodies that reduce turbulence

  20. Abdominal Cavity

  21. Digestive Tract

  22. Liver

  23. Reproductive Organs Dissection video

  24. Bony Fishes Section 39.3

  25. Characteristics • Bone: harder & heavier than cartilage • Lungs or swim bladder: early fish have lungs, most have a swim bladder(gas filled sac used to control buoyancy) • Scales: protect fish & reduce water resistance

  26. Lobed-Finned Fishes • Fleshy fins • Example: lungfish • Breath through lungs and gills • Live in shallow tropical ponds • Ancestors of amphibians & other terrestrial vertebrates Video

  27. Ray-Finned Fish • Rays: long, segmented, flexible bony elements that support the fins • Evolved from scales • Diverse in appearance, behavior, & habitat • Familiar fish Video

  28. External Anatomy • Distinct head, trunk, & tail regions • Operculum: hard plate that opens toward the rear and covers & protects gills • Caudal fin: extends from tail & moves side to side • Dorsal fins: anterior & posterior • Pelvic fins & pectoral fins: help navigate fish • Scales: skin of fish that grow quickly when food is abundant • Growth rings

  29. Caudal Fin Dorsal Fin Operculum Pectoral Fin Anal Fin Pelvic Fin

  30. Internal Anatomy • Skeleton = skull, spinal column, pectoral girdle, pelvic girdle, & rib • Pectoral girdle: where pectoral fins attach • shoulders • Pelvic girdle: where pelvic fins attach • hips

  31. Digestive System Video • Generalized carnivores • Predatory fish have jaws lined with inward pointing teeth • Path of food: • Mouth pharynx (throat cavity)  esophagus  stomach + enzymes  intestines (absorption of nutrients) + gallbladder that excretes bile (breaks down fats) from liver+ pancreas’ enzymes anus

  32. Circulatory System • Delivers oxygen & nutrients and removes waste carbon dioxide & ammonia • Consists of heart, blood vessels like capillaries, veins, & arteries

  33. The Heart • Two chambers in a row • Sinus venosus: deoxygenated blood empties into this collection area • Atrium: contractions move blood to the ventricle • Ventricle: main pumping chamber • Conus arteriosus: valves to prevent backflow of blood

  34. Respiratory System • Water goes into mouth, past gill filaments and out the operculum • Blood flows in a countercurrent flow opposite of water flow • Allows for more O2 diffusion

  35. Excretory System • Kidneys: dissolve chemical wastes from blood resulting in urine (with ammonia) • Urinary bladder: holds urine until expelled

  36. Swim Bladder • Thin walled sac in abdominal cavity • Contains a mixture of O2, CO2, and N2 • Enables movement up and down

  37. Nervous System • Contains brain, spinal cord, nerves, & sensory organs • Most sensory organs connected to brain via cranial nerves

  38. The brain • Olfactory bulb: processes info of smell • Cerebrum: integrates information for other areas of the brain • Optic tectum: processes info of sight • Cerebellum: coordinates motor output • Medulla oblongata: controls body functions

  39. Reproduction • Spawning: reproductive behavior of fish • Eggs & sperm released into water through opening behind anus • Most fish use external fertilization