Transcript Fish, Amphibians & Reptiles

Chordates and
Vertebrates
At one time in their development ALL chordates
have:
1.
2.
3.
4.
Notochord – flexible, rod-like structure along the back
of the organism
Postanal Tail
Nerve cord-tubular bundle of nerves that lies above the
notochord.
Gill Slits – paired openings located in throat behind
mouth. Develop into gills in fish. Traces can be seen in
embryos of many vertebrates INCLUDING humans!
Vertebrates
Have a backbone that encloses the nerve
cord.
 Most are ECTOtherms – internal body temp.
changes with its surroundings (fish,
amphibians, & reptiles)
 ENDOtherms – animals with constant internal
body temp. (Birds & Mammals)
 Endoskeleton: internal framework of bone
and cartilage
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7 Vertebrate groups
1.
2.
3.
4.
5.
6.
7.
Jawless Fish
Cartilaginous Fish
Bony Fish
Amphibians
Reptiles
Birds
Mammals
Fish
Ectotherms
 Adaptations for water:

Gills- organs for exchanging gas
 Fins – fan like structures, used for moving,
balance, and steering
 Scales – hard thin plates that cover skin,
provides protection
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3 classes: Jawless, Cartilaginous & Bony
Jawless Fish
Round mouths w/ long, tube-like bodies
covered in slimy skin w/ NO scales.
 Flexible bodies made of cartilage.
 EX: Lamprey & Hagfish
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Lamprey
HAGFISH
Skate
difference btw skate & ray
Cartilaginous Fish
Skeletons made of cartilage
 Movable jaws & Scales
 Ex: Sharks, Skates & Rays

Ray
Bony Fish
95% of all species of fish
 Gills protected by gill cover
 Swim Bladder
 Most have separate sexes
 Reproduce by females releasing large #
of eggs, & then males swim over eggs
and release sperm. Call this spawning.
 Form of External fertilization
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3 Classes
1. Lobe-finned Fish
2. Rayfinned fish
3. Lung fish
Swim Bladder
Buoyancy – ability of a
liquid or gas to exert an
upward force on an
object in it.
 Swim bladder allows it
to adjust its density so it
can rise or sink.
 Fills with gas-rises.
Deflates-sink.

Amphibians
Ectothermic vertebrates that spend part
of their life in water & part on land.
 Ex: Frog, toad & salamander
 Greek word “amphibios” means double
life

Amphibian Adaptations
Respiration:
-Moist, smooth, scaleless skin that allows gas
to be exchanged (breathe through skin)
-Also have small lungs to aid in breathing.
Hibernation – inactivity in winter
Estivation – inactivity in hot, dry summer
months.
 Eggs have no shell, so they must return to
water to lay eggs.
Difference Between Frogs &
Toads
FROGS
 smooth or slimy
skin
strong, long legs
webbed hind feet
two bulging eyes
lay eggs in clusters
TOADS
 warty and dry skin
stubby bodies with
short hind legs
Most have glands on
their back that secrete
poison
lay eggs in long
chains
Salamanders & Newts
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Long, slender bodies
Short legs that appear
to come straight out of
their side
Often found under dead
leaves and rocks during
the day
Often nocturnal, feeding
on worms, crustaceans
and insects
Difference btw salamander & Newt
Amphibian Metamorphosis
-Egg
-Tadpole (aka polliwog) spends its time
swimming in the water, eating and growing. Uses
gills to breathe, presence of a tail
-Tadpole w/ legs: tadpole sprouts legs and arms,
head becomes more distinct
-Froglet: stage before the adult frog. Tail is less
prominent.
Amphibian Metamorphosis
Metamorphosis: the development of an
animal from a larvae into an adult
 Amphibians usually complete their life cycles
in two environments
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Larvae: water
Adult: land
**Rate of metamorphosis depends on species and
nutrients available
Reptiles
Ectothermic vertebrate
 Dry, Scaly skin
 Often show maternal care (take care of
eggs or young)
Ex. Snakes, lizards, alligators, turtles

Adaptations for Life on Land
Thick, dry skin covered with scales
 4 legs with claws that hold body off
ground (except snakes)
 Amniotic egg
~provides environment for embryo to
develop
~leathery shell
Reptiles breathe with LUNGS!
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3 Orders of Reptiles
1.
2.
3.
Turtles
Crocodiles & Alligators
Lizards & Snakes
Turtles
Body covered by hard shell on both top
& bottom
 Most can withdraw partially into shell
for protection
 Have a BEAK (no teeth)
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Crocodiles & Alligators
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Crocs:
Long, slender snouts
Both bottom (4th
lower tooth)& Top
teeth stick out when
jaw closed
Found all over world
Aggressive
Alligators:
 Broad snouts
 Only top teeth stick
out, bottom teeth
have spots to fit in
so you do not see
them.
 Found only in South
East USA and China
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Lizards & Snakes
Largest group of Reptiles!
Lizards:
Snakes:
 Moveable eyelids  No moveable
eyelids, external
 External ears
ears, or legs with
 Legs with clawed
clawed toes
toes
 Hear by vibrations
picked up by lower
jaw bone
Venomous vs. Poisonous
There are NO poisonous snakes!!!
 Only Venomous
 Venom must be injected into the target
 Poison…found in skin or meat…can
cause problems if eaten or you come in
contact with it (ex Dart frogs)
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