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Chapter 31

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Title: Chapter 31


1
Chapter 31Fishes and Amphibians
  • Charles Page High School
  • Stephen L. Cotton

2
Section 31-1Fishes
  • OBJECTIVES
  • Describe the distinguishing characteristics of
    vertebrates.

3
Section 31-1Fishes
  • OBJECTIVES
  • Explain how fishes carry out their essential life
    functions.

4
Section 31-1Fishes
  • OBJECTIVES
  • Describe the three basic groups of fishes, and
    give an example of each.

5
Section 31-1Fishes
  • Is the name Earth appropriate for our planet,
    since more than 2/3 of it is water?
  • And, just about anywhere there is water- you can
    find fishes
  • We are studying the phylum Chordata- fish and
    other vertebrates have these features

6
Section 31-1Fishes
  • At some time in their life, they have
  • a notochord
  • a hollow dorsal nerve cord
  • pharyngeal slits (or pouches)
  • In vertebrates, the notochord is replaced by the
    vertebral column

7
Section 31-1Fishes
  • In addition, most vertebrates have
  • two sets of paired appendages
  • closed circulatory system with a ventral heart
  • either gills or lungs for breathing

8
Section 31-1Fishes (or is it Fish?)
  • Fishes- defined as aquatic vertebrates that are
    characterized by scales, fins, and pharyngeal
    gills
  • many varieties, such as some fish that have no
    scales
  • There are 4 living classes of vertebrates we know
    as fishes

9
Section 31-1Fishes
  • For our purposes, we can say that the living
    fishes fall into three main groups
  • 1. Jawless fishes
  • 2. Bony fishes
  • 3. Cartilaginous fishes

10
Section 31-1Fishes
  • Fishes are considered to be the most primitive
    living vertebrates
  • at first, they were odd-looking jawless creatures
    whose bodies were covered with bony plates
  • Figure 31-3, page 681
  • lived in the oceans of the late Cambrian period
    540 million

11
Section 31-1Fishes
  • For over 100 million years, fishes retained the
    basic armored, jawless body plan
  • then they underwent a major adaptive radiation
  • produced some jawless fishes that had little
    armor-ancestors of modern lamprey and hagfish

12
Section 31-1Fishes
  • Others produced were armored jawless fishes in a
    variety of new forms- were ultimately an
    evolutionary dead end
  • others were armored fishes that possessed a
    feeding adaptation that would revolutionize
    vertebrate evolution these fishes had jaws

13
Section 31-1Fishes
  • Jaws are extremely important evolutionary
    innovations
  • made it possible for vertebrates to nibble on
    plants, munch on other animals, and defend
    themselves by biting

14
Section 31-1Fishes
  • Another evolutionary innovation seen in early
    jawed fishes were paired pectoral (anterior) and
    pelvic (posterior) fins- attached to girdles of
    cartilage or bone
  • gave fishes more control over their movement in
    water
  • Figure 31-4, page 681

15
Section 31-1Fishes
  • The pectoral fins and girdle also provided the
    raw material from which evolution shaped the
    forelimbs and shoulder bones of terrestrial
    vertebrates
  • pelvic fins and girdles were also the origins of
    the hind limbs and hip bones

16
Section 31-1Fishes
  • The early jawed fishes soon disappeared but they
    left behind two major classes that continued to
    evolve- still survive today
  • the cartilaginous fish, including the sharks and
    rays
  • the bony fish, containing more than 97 of all
    living fish species

17
Section 31-1Fishes
  • Feeding- every mode of feeding is seen in fishes
    herbivores, carnivore, parasite, filter feeder,
    and even detritus feeder
  • a single fish may exhibit several methods of
    feeding
  • Parasite the pencil catfish lay their eggs and
    live in gills of other larger fishes

18
Section 31-1Fishes
  • Parasite the male of certain anglerfish attaches
    permanently to the much larger female, and
    obtains nutrients from her blood
  • Figure 31-5, page 682
  • Filter feeders the lamprey larvae and the manta
    rays not all small however the filter-feeding
    whale shark (18.5 meters)-largest fish!

19
Section 31-1Fishes
  • Adaptations for feeding are often quite
    remarkable
  • the sawfish (relative of sharks) kills and stuns
    prey by slashing into a school of small fish with
    a long snout edged with sharp teeth- Figure 31-5,
    page 682

20
Section 31-1Fishes
  • Parrotfish- has teeth fused into a short beak
    used to bite off chunks of coral, and additional
    teeth in the throat that grind the chunks of
    coral into sand
  • Archerfish- shoots down insects by spitting drops
    of water

21
Section 31-1Fishes
  • Anglerfish- have wormlike or lighted lures used
    to attract prey
  • Figure 31-1, page 679
  • some deep-sea fishes have enormous jaws that
    allow them to swallow prey larger than themselves

22
Section 31-1Fishes
  • Most fishes do not really chew their food
  • instead, they tear their food into conveniently
    sized chunks, or swallow their prey whole
  • Note the digestive system in Figure 31-6, page
    683 Lets examine this system

23
Section 31-1Fishes
  • Pathway
  • mouth food enters here
  • esophagus short tube
  • stomach food partially broken down
  • pyloric ceca between stomach and intestine
    further digested

24
Section 31-1Fishes
  • Pathway (continued)
  • pyloric ceca also secrete digestive enzymes and
    absorb nutrients from the digested food
  • intestine completes digestion receives enzymes
    from liver and pancreas
  • anus eliminate undigested items

25
Section 31-1Fishes
  • The fishs intestine is adapted in ways that help
    them meet their nutritional needs
  • herbivores typically have a longer intestine
    more time and space to break down plant matter,
    which is difficult to digest

26
Section 31-1Fishes
  • Lampreys, cartilaginous fishes, and a few bony
    fish have a flap of tissue that spirals around
    the outside part of the intestine this increases
    the surface area for nutrient absorption
  • Respiration- most breathe with gills on each side
    of the pharynx

27
Section 31-1Fishes
  • These feathery gills have many capillaries
    provide a large surface area for gas exchange
  • most breathe by pumping water through the mouth,
    over the gill filaments, and out through slits in
    the sides of the pharynx

28
Section 31-1Fishes
  • Some fishes, such as the sharks and lampreys,
    have several gill slits on either side of the
    pharynx
  • in many fishes, this basic respiratory setup has
    been modified by the evolutionary process skates
    and rays inhale from openings on the top side

29
Section 31-1Fishes
  • Many fishes (lungfish, gars, Siamese fighting
    fish) have adaptations that allow them to survive
    in oxygen-poor water, or in areas where water
    dries up
  • have specialized organs that serve as lungs by
    obtaining oxygen from the air

30
Section 31-1Fishes
  • In most air-breathing fishes, this organ is
    actually a modified swim bladder
  • the swim bladder (found in most bony fish) is a
    gas-filled sac that lies at the top of the body
    cavity just beneath the backbone- regulates
    buoyancy

31
Section 31-1Fishes
  • This swim bladder allows the fish to swim at
    different depths
  • Internal Transport- typically have a closed
    circulatory system with a heart that pumps blood-
    p.685
  • two-chambered heart an atrium(collecting
    chamber), and a ventricle (pumping chamber)

32
Section 31-1Fishes
  • Blood is pumped out of the ventricle into a
    muscular vessel called the aorta, and then into
    the fine capillary network of the gills where gas
    exchange occurs
  • after gills, travels to rest of the body
    collects in the veins, to the sinus venosus, then
    atrium

33
Section 31-1Fishes
  • Excretion- like most other aquatic forms, fishes
    get rid of nitrogenous wastes in the form of
    ammonia
  • some wastes diffuse through the gills others
    removed by the kidneys

34
Section 31-1Fishes
  • Kidneys help fishes control the amount of water
    in their bodies
  • fishes in salt water tend to lose water by
    osmosis the kidneys thus concentrate the urine
    to reduce water loss
  • however, freshwater fishes need to pump out lots
    of dilute urine

35
Section 31-1Fishes
  • Response- fairly well developed nervous system
    organized around a brain-anterior parts are
  • the olfactory lobes (smell) connected to the
    cerebrum
  • cerebrum also helps with taking care of young
    exploring areas

36
Section 31-1Fishes
  • optic lobes- process information from the eyes
  • cerebellum- coordinates body movements
  • medulla- controls many internal organ functions
    and maintains balance

37
Section 31-1Fishes
  • Posterior to the brain is the spinal cord, which
    is in fact the hollow dorsal nerve cord that
    characterizes chordates
  • Figure 31-9, page 685
  • superbly designed sense organs to collect
    information about their environment

38
Section 31-1Fishes
  • Almost all fishes are active in the daylight
    well developed eyes and color vision
  • fish active only at night, or in cloudy water,
    have large eyes with big pupils that gather as
    much light as possible

39
Section 31-1Fishes
  • Some have extraordinary senses of taste and smell
  • chemoreceptors located all over the head and much
    of the rest of the body, as well as nose and
    mouth possibly on their whiskers like catfish

40
Section 31-1Fishes
  • Salmon can distinguish between the odor of their
    own home stream while still far out to sea
  • sharks can detect the presence of a drop of blood
    in 115 liters of sea water
  • ears are inside their heads, but do not really
    hear well

41
Section 31-1Fishes
  • Instead of hearing, they detect gentle currents
    and vibrations in the water
  • have lateral line system that can detect others
    around them allows them to swim in orderly
    formations

42
Section 31-1Fishes
  • Some fishes- electric eels, catfish, and sharks-
    are able to detect electricity
  • a shark can detect one millionth of a volt, which
    is less than the charge produced by the nerves in
    an animals body
  • help locate prey in murky water

43
Section 31-1Fishes
  • In addition, electric fishes can produce jolts of
    electricity (up to 650 volts) that stun or kill
    prey and discourage predators
  • Reproduction- in most species, there are separate
    males and females some may be born male, but
    change into females as they age

44
Section 31-1Fishes
  • Many fishes are oviparous- which means the lay
    eggs
  • most oviparous fishes have external
    fertilization some may fertilize internally,
    then lay fertilized eggs
  • some,such as cod, do not take care of their young
    at all

45
Section 31-1Fishes
  • Others may care for their offspring
  • Siamese fighting fish build nests of bubbles
  • sticklebacks build nests of twigs
  • cichlids and catfish may hold eggs in their mouth
    until hatch

46
Section 31-1Fishes
  • In some of the fishes that have internal
    fertilization, such as guppies, the eggs will
    develop inside the females body
  • they are nourished by food stored in an attached
    yolk sac, not the mothers body directly
  • called ovoviviparous

47
Section 31-1Fishes
  • In other species, including several sharks, the
    young are actually nourished by the mothers body
    as they develop
  • called viviparous, or truly live-bearing
  • Fascinating mating behaviors dances, show color,
    building nests

48
Stop Day 1
49
Section 31-1Fishes
  • Jawless Fishes- those alive today are divided
    into 2 classes the lampreys and hagfishes
  • thought to have evolved from the heavily armored,
    bony ancestors, these actually have no bones at
    all only vertebrate with no backbone as adults
    have only the notochord

50
Section 31-1Fishes
  • Lampreys- typically filter feeders as larvae, and
    parasites as adult
  • head taken up almost completely by a circular
    sucking disk with a round jawless mouth in the
    center - page 687
  • attach to fishes make wound suck up tissues and
    body fluid

51
Section 31-1Fishes
  • Hagfishes- probably the most primitive
    vertebrates alive today
  • pinkish-gray wormlike bodies and 4 or 6 short
    tentacles around the mouth
  • lack eyes have light detecting regions around
    their bodies

52
Section 31-1Fishes
  • Feed on dead and decaying fish by using a toothed
    tongue to scrape a hole into the fishs side
  • peculiar traits secrete incredible amounts of
    slime have 6 hearts open circulation regularly
    tie themselves into half-knots

53
Section 31-1Fishes
  • Class Chondrichthyes- sharks, rays, skates,
    sawfish and chimaeras
  • ancient and successful group
  • chondros- means cartilage ichthys means fish
  • endoskeleton built entirely out of cartilage

54
Section 31-1Fishes
  • Most also have tooth-like scales covering the
    skin making the sharkskin so rough that it is
    possible to use as sandpaper
  • Shark characteristics large curved tail round
    snout, mouth underneath torpedo shape enormous
    number of teeth teeth continually replacing lost
    ones

55
Section 31-1Fishes
  • Not all sharks are man-eaters
  • some are filter feeders, others have flat teeth
    adapted for crushing the shells of mollusks and
    crustaceans
  • more people are killed by lightning each year
    than sharks

56
Section 31-1Fishes
  • Unlike sharks, which are adapted for swimming
    rapidly through the water, rays and skates are
    adapted for living on the ocean floor
  • flattened from top to bottom (like squashed
    sharks) flap their large pectoral fins to swim

57
Section 31-1Fishes
  • Class Osteichthyes- bony fish
  • more species in this class than in any of the
    other vertebrate classes
  • about 40 of all vertebrates are bony fishes

58
Section 31-1Fishes
  • Almost all bony fishes belong to the enormous
    group called the ray-finned fishes- anything from
    guppies to salmon to eels
  • ray-finned refers to the thin bony spines, or
    rays, that are connected by a thin layer of skin
    to form the fins

59
Section 31-1Fishes
  • The fins are adapted to a wide variety of
    functions
  • some have them modified into poison spines
  • some glide (fly) with wing-like pectoral fins
  • may use a suction cups to climb

60
Section 31-1Fishes
  • Only 7 living species of bony fishes are not
    classified as ray-finned fishes
  • these are the lungfishes and the coelacanth
  • The 6 species of lungfish alive today live in
    Australia, Africa, and South America

61
Section 31-1Fishes
  • Sometimes these areas are very wet, but other
    times very dry
  • when water is available, they use their gills-
    but often gulp air into a sac used as a lung
  • during the dry season, they may burrow in the mud
    and enter a dormant state

62
Section 31-1Fishes
  • The single species of coelacanth alive today,
    Latimeria, is the only surviving member of the
    lobe-finned fishes
  • unlike ray-finned fish with bones in the base of
    the rays, lobe-finned fish have few bones in
    their fin bases

63
Section 31-1Fishes
  • Ancient lobe-finned fishes seemed to have lived
    in swampy areas where shallow pools alternated
    with mud flats and sand bars
  • they probably used their pelvic and pectoral
    appendages to move from pool to pool

64
Section 31-1Fishes
  • Coelacanths were thought to have disappeared with
    dinosaurs about 70 million years ago
  • in 1938 however, some fishermen caught a strange
    blue fish thus, they were not extinct after all-
    important as they are the closest ancestors to
    all land vertebrates

65
Section 31-1Fishes
  • How Fishes Fit Into the World- vital parts of
    many biological systems as
  • food for many animals
  • predators to control others
  • keep waterways clear of plants
  • pets brightly colored to watch

66
Section 31-2Amphibians
  • OBJECTIVES
  • Describe how a typical amphibian carries out its
    essential life functions.

67
Section 31-2Amphibians
  • OBJECTIVES
  • Compare the two major living orders of amphibians.

68
Section 31-2Amphibians
  • Class Amphibia- with about 4,000 living species,
    they are the smallest major group of vertebrates
  • range in size from a tiny tropical tree frog 1 cm
    long, to enormous salamanders 170 cm long

69
Section 31-2Amphibians
  • Some amphibians, such as salamanders and newts,
    have long tails and scuttle about on 4 legs
  • others, such as frogs and toads, have no tails
    can leap from place to place with large hind legs

70
Section 31-2Amphibians
  • Still others , like caecilians (p.693) have no
    legs at all, and burrow in soil like giant worms
  • Although many of these animals spend a great deal
    of time on land, nearly all of them are
    restricted to moist areas, and most return to
    water to breed

71
Section 31-2Amphibians
  • The name amphibian refers to the double like most
    amphibians lead
  • amphi- means both bio- means life
  • larvae are fishlike aquatic animals that breathe
    through gills

72
Section 31-2Amphibians
  • The adults are terrestrial carnivores that
    breathe through lungs and skin
  • the majority of amphibians live in water for the
    first part of their life, and on land as adults
  • the aquatic larvae is one reason they live in
    moist areas

73
Section 31-2Amphibians
  • Most important reason they live in a moist area
    their eggs do not have a shell, thus tend to dry
    out unless found in moist areas
  • also, they do not have scales, fur, or any other
    protective covering that would help prevent
    drying out

74
Section 31-2Amphibians
  • Amphibians are vertebrates that
  • 1) Are aquatic as larvae and terrestrial as
    adults
  • 2) Have gills as larvae, and lungs as adults
  • 3) Have a moist skin that contains many glands
  • 4) Lack scales and claws

75
Section 31-2Amphibians
  • Evolution of Amphibians- appeared around the end
    of the Devonian period, about 360 million years
    ago
  • probably evolved from lobe-finned fishes, similar
    to modern coelacanth, that had bones in their fin
    bases and lungs

76
Section 31-2 Amphibians
  • The transition from water to land is no easy
    task
  • 1) gills were now useless
  • 2) appendages for water (fins) are too weak to
    support much weight on land
  • 3) loss of water is a constant danger
  • 4) vibrations in air are less than in water, thus
    it is more difficult to detect sound and movement
    in air

77
Section 31-2Amphibians
  • Early amphibians evolved ways to correct these
    problems
  • bones of the limbs and limb girdles become
    stronger
  • ribs form a bony cage to protect internal organs
  • scales that protect skin on the underside

78
Section 31-2Amphibians
  • Ears that used a membrane to transmit sound waves
    in the air into pressure waves in body fluids
    were added to their lateral line systems
  • mucous glands, eyelids, and other structures that
    protect sense organs from drying out

79
Section 31-2Amphibians
  • Early amphibians soon underwent a major adaptive
    radiation
  • some ancient forms were huge
  • so numerous during the Carboniferous Period
    (345-285 million years ago) that it became known
    as the Age of Amphibians

80
Section 31-2Amphibians
  • Why were amphibians so successful?
  • They entered an environment nearly empty of
    animal life
  • because plants and arthropods were already on
    land, there was plenty of food- with no
    competitors full of empty niches

81
Section 31-2Amphibians
  • The successful heyday of amphibians was
    short-lived.
  • climate changes caused many of the low, swampy
    habitats to disappear
  • many amphibian groups were extinct by the end of
    the Permian Period, 245 million years ago

82
Section 31-2Amphibians
  • What was left after this period of extinction was
    four groups of land vertebrates
  • the reptiles, which evolved from amphibians early
    in the Carboniferous Period and three orders of
    small amphibians

83
Section 31-2Amphibians
  • Feeding- tadpoles (the larvae of frogs and toads)
    are typically filter feeders or herbivores
  • as herbivores, they have long, coiled intestines
    that break down hard-to-digest plant food
  • tadpoles grow quickly before the water disappears

84
Section 31-2Amphibians
  • Feeding- adult amphibians are almost entirely
    carnivorous
  • salamanders and legless amphibians can only snap
    their jaws open and shut to catch prey
  • frogs have a long sticky tongue specialized to
    capture insects

85
Section 31-2Amphibians
  • Feeding- Note Figure 31-20, page 696 that shows
    the digestive system of the frog
  • mouth esophagus stomach small intestine (has
    digestive enzymes as well as absorbs food) large
    intestine (colon) cloaca (stores wastes)

86
Section 31-2Amphibians
  • There are tubes that connect the intestine with
    organs that also produce digestive enzymes, such
    as the
  • liver pancreas and gall bladder

87
Section 31-2Amphibians
  • Respiration- adults typically breathe using
    lungs mouth cavities and skin
  • in frogs and toads, the lungs are reasonably
    well-developed and richly supplied with
    capillaries and folds that increase their surface
    area

88
Section 31-2Amphibians
  • Respiration- other amphibians may not have lungs
    that are well developed many terrestrial
    salamanders have no lungs at all
  • The lining of the mouth cavity and skin is thin
    and richly supplied with capillaries to serve as
    gas-exchange organs

89
Section 31-2Amphibians
  • Respiration- tadpoles, salamander larvae, and few
    types of adult salamanders breathe primarily
    through their gills however, they can get rid of
    excess carbon dioxide through their skin

90
Section 31-2Amphibians
  • Respiration- because they do not have the
    necessary chest and stomach muscles, frogs cannot
    inhale and exhale as we do
  • they fill their mouth with air close their
    mouth force air back through an opening called
    the glottis into the lungs

91
Section 31-2Amphibians
  • Respiration- frogs can also direct some of the
    air they take in to a pair of expandable vocal
    sacs in the rear of the mouth
  • Figure 31-21, page 697
  • frogs croak by forcing air from these sacs over
    vocal cords, both directions, even under water

92
Section 31-2Amphibians
  • Internal Transport- the circulatory system in the
    adult amphibians is closely linked to the
    development of lungs
  • Adults have a double-loop
  • First loop carries oxygen-poor blood from heart
    to lungs then oxygen-rich blood back to heart

93
Section 31-2Amphibians
  • Second loop transport the oxygen-rich blood from
    the heart to the rest of the body and
    oxygen-poor blood from the body back to the heart
  • Thus, blood travels through the heart twice in
    one circulation hence the name double-loop

94
Section 31-2Amphibians
  • Amphibian heart has 3 separate chambers
  • left atrium right atrium, and ventricle
  • blood returning from the body collects in a large
    vein called the vena cava

95
Section 31-2Amphibians
  • The vena cava and other veins that drain the head
    and skin empty into the sinus venosus, which
    empties into the right atrium
  • blood returning from the lungs in the pulmonary
    vein enters into the left atrium

96
Section 31-2Amphibians
  • When the atria contract, they empty the blood
    into a single ventricle
  • then it pumps blood into a single large vessel
    called the bulbus cordus, which divides into a
    series of aortic arches that lead to major body
    arteries

97
Section 31-2Amphibians
  • A three-chambered heart is much better than the
    fishes two-chambered heart it allows a return to
    the heart for an extra burst of power before
    going to the body
  • tadpoles have two-chamber heart much like bony
    fishes become adults- it changes to 3-chamber

98
Section 31-2Amphibians
  • Excretion- use kidneys to eliminate waste from
    bloodstream
  • these lie against the dorsal body wall
  • filter nitrogenous wastes
  • the urine travels through tubes (ureters) to the
    cloaca here it can be stored or eliminated

99
Section 31-2Amphibians
  • Response- have well developed nervous and sensory
    systems
  • eyes are large, and move in the sockets quite
    well surface of eye is protected from damage
    under water and kept moist on land by a
    transparent nictitating membrane located inside
    the eyelid- which can also close

100
Section 31-2Amphibians
  • Ears are quite sensitive, even though they have
    no external sound collectors
  • a variety of croaks, peeps, and other calls to
    find a mate thus hearing is vital to their
    survival and reproduction

101
Section 31-2Amphibians
  • Response to adverse environmental conditions is
    done in a variety of ways
  • no internal mechanism for regulating body
    temperature (they are called cold-blooded), but
    find a sheltered spot or enter a dormant state

102
Section 31-2Amphibians
  • Amphibians are clawless, soft-skinned- ways of
    protection?
  • Some hide others run quickly some are
    well-camouflaged may produce distasteful or
    toxic chemicals (Fig. 31-23, p.698)
  • the more toxic amphibians usually have warning
    coloration

103
Section 31-2Amphibians
  • Reproduction- male climbs on the females back
    and squeezes
  • in response, the female releases many eggs, which
    are then fertilized by the male- external
    fertilization
  • Figure 31-24, page 699

104
Section 31-2Amphibians
  • The frog embryos are surrounded by a sticky,
    transparent jelly that attaches the egg mass to
    underwater plants, as well as nourishes the
    embryo
  • typically hatch into tadpoles after one to three
    weeks

105
Section 31-2Amphibians
  • Not all amphibians have external fertilization
    and are oviparous like frogs
  • many do have internal fertilization, and are
    either oviparous, ovoviviparous, or viviparous

106
Section 31-2Amphibians
  • Parental care varies- this is a way of ensuring
    that more young will survive
  • carry and incubate the young in their mouth,
    vocal sac, or stomach
  • may carry them on legs or back until eggs are
    ready to hatch

107
Section 31-2Amphibians
  • Health Link the old wives' tale that toads cause
    warts probably came about because of the warty
    appearance of a toads skin
  • In fact, viruses cause warts, not toads

108
Section 31-2Amphibians
  • Salamanders- these amphibians keep their tails
    even as adults
  • both adult and larvae are carnivores
  • fossils forms may have been more then 3 meters
    modern forms about 15 centimeters

109
Section 31-2Amphibians
  • Salamanders- hatch as fully aquatic larvae with
    gills as adults, they live in most woods under
    rocks and rotting logs
  • some, such as the mud puppy and axolotl never
    lose their gills live in water all their life

110
Section 31-2Amphibians
  • The crimson-spotted newt switches back and forth
    between water and land
  • starts as aquatic larvae emerge and live on land
    as a form called the red eft then changes color
    to green with red spots returns to water to breed

111
Section 31-2Amphibians
  • Frogs and Toads
  • frogs are more closely tied to water, and spend
    much of their time in or near ponds and streams
  • toads are better adapted to land because their
    warty skin helps conserve water- often live in
    most woods under rocks and rotting logs

112
Section 31-2Amphibians
  • How Amphibians Fit Into the World
  • adults prey on insects
  • tadpoles devour large amounts of algae
  • eat frog legs?
  • toxins on arrow tips

113
Section 31-2Amphibians
  • How Amphibians Fit Into the World
  • toxins give us clues to nervous systems
  • salamanders regenerate frogs cannot- Why?
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