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
Endoskeleton composed 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 Lamprey Sharks, Rays & Skates
Class Myxini
Lamprey
Class Cephalaspidomorphi
Sharks, Rays & Skates
– Class Chondrichthyes
Ray-Finned Fish
Class Actinopterygii
Lobed-Finned Fish
Class Sarcopterygii

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

10. Jawless & Cartilaginous Fishes
Section 39.2

11. 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. Homeostasis 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. 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 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 Examples: Sharks, rays, & skates
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
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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 Video 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 Video 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. External Anatomy Anterior Dorsal Fin Lateral Line Caudal Fin Nares
Posterior Dorsal Fin
Eye
Anal Fin
Operculum
Pectoral Fin
Pelvic Fin

31. 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

36. Digestive System Generalized carnivores
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

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

38. 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

39. 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

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

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

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

44. 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

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

46. Fish Dissection

47. Close-up: Body Cavity Ovary Muscle Swim Bladder Eggs Liver
Stomach
Gastric Cecae
Small Intestine
Spleen

48. Anterior View 1. Gills 2. Heart 3. Liver 4. Pyloric caeca
5. Small intestine
6. Stomach
7. Swim bladder

49. Posterior View 1. Swim bladder 2. Gonad 3. Large intestine
4. Urinary bladder
5. Anus