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Chapter 30 Fishes and Amphibians

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Some cartilaginous fish (such as sharks) have internal fertilization and few eggs at a time ... Sharks are considered living fossils' having changed little in ... – PowerPoint PPT presentation

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Title: Chapter 30 Fishes and Amphibians


1
Chapter 30 Fishes and Amphibians
  • 30.1 Fishes
  • 30.2 Amphibians

2
Fish have all the characteristics of a chordate
  • Notochord
  • gill slits
  • muscle blocks
  • hollow dorsal nerve cord
  • bilateral symmetry
  • Endoskeleton
  • Coelomate
  • Closed circulatory systems
  • Complex brains
  • Sense organs
  • Efficient respiratory

3
3 Classes of Fish
  • Agnatha jawless fish, lampreys and hagfish
  • Chondrichthyes cartilaginous fish, rays, and
    sharks
  • Osteichthyes bony fish

4
Fish
  • More than 200,000 species of fish. Mort being
    discovered all the time
  • 95 are Osteichthyes
  • Inhabit nearly every aquatic environment on the
    planet

5
Fish use gills to breathe
  • Gills are made up of feathery filaments that
    contain tiny blood vessels.
  • Water goes in the mouth over the gills and then
    out through slits on the side of the fish
  • Oxygen and Carbon Dioxide are exchanged through
    the capillaries

6
Circulation in fish
  • 2 chambered heart
  • Closed circulatory system
  • Blood flow is relatively slow because most of the
    pump action is used to get blood through the gills

7
Sexual reproduction
  • All fish have separate sexes
  • Most have external fertilization
  • Produce large numbers of eggs at one time
  • Some cartilaginous fish (such as sharks) have
    internal fertilization and few eggs at a time
  • Reproduction in fish is often called spawning
  • Most do not care for offspring after spawning
  • Some fish have internal fertilization and live
    birth (live bearers)
  • Live bearers MAY care for young for a short time

8
Fins
  • Fan shaped membranes used for steering, swimming
    and balance
  • Most have paired fins
  • Attached to and supported by the endoskeleton
  • Paired fins evolved into limbs in other animals
    and wings for birds

9
Sensory Systems
  • All fish have highly developed sensory systems
  • Lateral line system in bony fish, a series of
    fluid filled canals running along their sides
    that let it sense movement and vibration in the
    water
  • Some (like sharks) also have acute senses of smell

10
Scales
  • Hard bony plates formed from the skin
  • Can be toothlike, diamindshaped, coneshaped or
    round.
  • Some fish (like catfish ) dont have scales
  • Shark scales are like the teeth of other species
  • Can use the annual growth rings in the scales to
    tell age in some species

11
Jaws
  • One of the most important traits vertebrates
    evolved
  • Jaws let animals grasp and crush prey

12
95 of fish have skeletons of bone
  • Bone hard, mineralized living tissue
  • Makes up the endoskeleton
  • Bone allowed fish to adapt to lots of habitats
    and eventually to living on land
  • separate vertebrae allow for flexibility

13
Swim Bladder
  • A thin walled internal sac found just below the
    backbone in bony fish
  • Can be filled with oxygen and nitrogen gas that
    diffuses out of the blood
  • Allows fish to adjust their buoyancy (lets them
    rise or sink in the water) by putting more gas in
    or letting it out

14
Diversity of fish
15
Agnathans jawless fish
  • Lampreys and hagfish
  • No jaws but are heavy feeders
  • They have teeth
  • Hagfish attach themselves and drill a hole in
    their prey with their teeth and suck out the
    insides
  • Skeletons are made of cartilage

16
Cartilaginous fish
  • Sharks, rays and skates
  • Skeletons made entirely of cartilage
  • Sharks are considered living fossils having
    changed little in hundreds of thousands of years.
  • All are predators
  • Some have poison glands or may generate
    electricity for defense or feeding

17
3 sub-classes of bony fish
  • Lungfishes - Have both gills and lungs
  • Lobe-finned fishes - only one living species
    (coelacanth) fins are fleshy and used to walk
    along the seafloor. Are the ancestor of all
    tetrapod (4 legged) animals
  • Ray finned fish fins are fan shaped membranes
    supported by spines called rays. Catfish, tuna,
    salmon

18
Origins of Fish
  • Evolved during the Ordovician period more than
    500 million years ago
  • jawless fish were the 1st fishes
  • Ostracoderms were heavy armored, jawless fish
    with cartiliginous skeletons but bony shields
    over their heads and necks
  • From these evolved the bony fish of today some
    time during the Devonian period
  • bony fish evolved during the Devonian period (400
    million years ago)

19
30.2 Amphibians
  • Amphibia means double life
  • Includes 3 orders
  • Caudata ( salamanders and Newts)
  • Anura (frogs and toads
  • Apoda ( legless caeecians

20
Characteristics
  • Thin, moist skin
  • 4 legs (except for the apoda)
  • No claws on their toes
  • Most live on land as adults
  • Require water for reproduction
  • Fertilization is usually external
  • Water is needed to transport sperm so eggs are
    usually laid in water
  • No protective membranes or shells on their eggs

21
Amphibians are ectotherms
  • Ectotherms (cold-blooded) are the same
    temperature as the surrounding air or water
  • Must live in places that are warm all year round
    or must hibernate when its too cold
  • May also enter a state of estivation (like
    hibernation) if it gets too hot

22
Metamorphosis
  • Eggs hatch into tadpoles (aquatic stage)
  • Tadpoles have gills, fins, tails and a 2
    chambered heart JUST LIKE FISH
  • Then change and develop into their adult form
    over time
  • Adults have lungs, legs and a 3 chambered heart
  • Salamander young look like the adults but have
    gills not lungs. Some species dont get lungs
    and breathe through their skin

23
Walking and Oxygen
  • Walking requires lots of energy
  • Need more food and oxygen to move muscles to walk
  • The 3 chambered heart allows for enough oxygen to
    get to the cells
  • There is some mixing of oxygen rich and oxygen
    poor blood in the 3rd chamber

24
Amphibian skin
  • Must remain moist so they can exchange gasses
    through it
  • Toads have thicker skin and may live mainly on
    land, but must return to water to reproduce

25
Diversity of Amphibians
26
Anura frogs and toads
  • No tails
  • Breathe through lungs
  • Frogs - long hind legs and smooth moist skin
  • Toads bumpy dry skin and short legs
  • All eat insects
  • Many secrete chemicals through their skin for
    defense
  • Have vocal cords and produce loud mating calls
  • Spend part of their lives in the water and part
    on land but must return to water to reproduce

27
Caudata - Salamanders
  • Long slender body
  • Look like lizards but have smooth moist skin and
    no claws
  • Some are completely aquatic, others live in damp
    places on land
  • Range in size from a few centimeters to 5 feet
  • Young look like adults
  • All are carnivorous

28
Caecilians
  • Limbless amphibians
  • Short or no tail
  • Mainly tropical
  • Small eyes often blind
  • Eat earthworms and other invertebrates found in
    soil

29
Origins of Amphibians
  • Evolves some 350 million years ago as a tetrapod
    fish began to come onto land
  • Earliest ones had both lungs and gills and likely
    could move over mud to get to another water
    source (a serious advantage)

30
Life on Land
  • Life on land was very advantageous for early
    amphibians - no predators lots of food and
    shelter
  • but air temperatures vary greatly and they had
    to remain where it was warm or evolve hibernation
    and estivation abilities
  • Early land movement was probably clumsy and slow
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