Fishes

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
• 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
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 fishs 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

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33
Circulatory System

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

34
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

35
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

36
Excretory System

• Kidneys dissolve chemical wastes from blood
  resulting in urine (with ammonia)
• Urinary bladder holds urine until expelled

37
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38
Swim Bladder

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

39
Nervous System

• Contains brain, spinal cord, nerves, sensory
  organs
• Most sensory organs connected to brain via
  cranial nerves

40
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

41
Reproduction

• Spawning reproductive behavior of fish
• Eggs sperm released into water through opening
  behind anus
• Most fish use external fertilization

42
Fish Dissection
43
Close-up Body Cavity
44
Anterior View
1. Gills 2. Heart 3. Liver 4. Pyloric caeca 5.
Small intestine 6. Stomach 7. Swim bladder
45
Posterior View
1. Swim bladder 2. Gonad 3. Large intestine 4.
Urinary bladder 5. Anus