Transcript Vertebrates: Fishes to Reptiles

Non-vertebrate
Chordates, Fishes, and
Amphibians
Chapter 30
Phylum Chordata
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Contains three sub-phyla:
– Vertebrata
– Urochordata
– Cephalochordata
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All chordates at some point in their life
span must possess four characteristics:
1)
2)
3)
4)
A hollow, dorsal nerve cord
A notochord (supporting rod)
Pharyngeal gill slits
A tail that extends beyond the
anus
Also known as the tunicates or “sea
squirts”
 Basically a sack with two siphons.
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Examples: amphioxus and lancelets
Vertebrates
Most numerous chordates
 Anterior, large brain
 Jointed internal skeleton
 Usually two pairs of appendages and
some type of tail
 Closed circulatory system
 Gills or lungs and a chambered heart
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7 major classes of vertebrates
Jawless fishes, cartilaginous fishes,
bony fishes, amphibians, reptiles, birds,
mammals
 Ectotherms = “cold-blooded” body temp
changes with the environment.
 Endotherms = “warm blooded” body
tem remains fairly constant
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FISH or FISHES
Both words can be used for the plural of
a fish.
 “Fishes” is often used when talking
about taxonomy or classification.
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1. Class Agnatha
“jawless fishes”
 Most primitive vertebrates
 No scales nor fins
 Cartilage skeleton
 No jaws
 Both fresh and salt water varieties.
 examples: lampreys and hagfish
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LAMPREY
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Both fresh and salt
water. (parasitic)
Possess a tongue
with teeth that gnaw
a hole in its victim
then sucks out the
blood.
Can be harmful to
fish populations.
HAGFISH
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Only found in salt
water. scavengers
Also known as
“slime eels”
Produce great
amounts of slime for
defense. Can tie
themselves in a knot
2. Class Chondricthyes
Chondros (Gr. Cartilage)
 Ichthys (Gr. Fish)
 Mostly marine
 2 chambered heart
 Movable upper and lower jaws
 ex. Sharks, skates, and rays
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Skates and rays
Flattened body (countershading)
 Eat worms, mollusks, and other
invertebrates
 Can be specialized for defense
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– Stingers
– Electric rays
SHARKS
Internal fertilization.
Viviparous = live birth
Need to be constantly swimming to
keep water moving over the gills
Very highly developed sense of smell.
Covered with sandpaper-like scales
called placoid scales.
Medicinal uses
 Currently
shark
cartilage is
being tested
as a possible
cure for
cancer.
3. Class Osteicthyes
Osteo- Gr. Meaning “bone”
Known as the bony fishes
Largest class of vertebrates.
Vary in size, shape, and structure.
Complex nervous system (lateral lines)
Very specialized.
Electric eel, pufferfish, angler fish, butterfly
fish
Wide Variety
Structure of a bony fish
Usually four pairs of gills covered by a
bony flap (operculum)
 2 chambered heart
 Many have scales and fins
 Swim bladder = gas-filled sac which is
used for buoyancy (maintain depth)
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Reproduction
 External.
 A female
will lay upto
500,000 eggs.
 The male usually swims over
the eggs depositing milt
(sperm containing fluid)
The Coelacanth
A special fleshy-lobed finned fish
thought to be extinct.
 1938 one was caught off the southern
coast of Africa.
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4. Class Amphibia
“from water to land”
 Reproduction and development must
take place in or near water.
 Thin moist skin
 Two pairs of limbs, one pair of nostrils
 3 chambered heart
 Young show a distinct larval form.
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Examples:
Frog anatomy and function
Large powerful hind legs for jumping.
 2 large movable eyes
 Tympanic membrane
 3 eyelids
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– Upper
– Lower
– Nictitating membrane (transparent; used
for underwater sight.
digestion
Large mouth.
 Long sticky spade-shaped tongue
 Teeth along upper jaw.
 A pair of vomerine teeth used to hold
prey in mouth
 Esophagus...stomach...small
intestine(site of absorption)..large
intestine...cloaca…anal opening.
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Circulatory system
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Oxygenated blood enters left atrium from
lungs. Deoxygenated blood enters right
atrium from rest of body.
Both empty into ventricle where a mixture of
oxygen and non-oxygen blood is pumped out
Respiratory system
Tadpoles use gills to breathe.
 Adult frog uses three structures for
respiration.
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Nervous system
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Possess both a cranial and peripheral
nervous system
Multi-lobed brain
Olfactory(smell)
Optic(sight)
Cerebrum(voluntary muscles)
Cerebellum(coordination)
Medulla(involuntary muscle action)
Excretory system
 CO2
excreted through the skin,
other wastes filtered through
the kidneys.
 Urine is stored in urinary
bladder then passed into cloaca
and out of the body.
Reproduction
External
fertilization
 amplexus = male
grasps female,
eggs are released
then quickly
fertilized by the
male.
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Order Urodela
 Salamanders
and newts
 Long bodies
and tails
 Live in dark,
moist places.
Orders Anura & Apoda
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ANURA
Frogs and toads
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APODA
Caecilians
Legless amphibians
Assignment
Pages 793-794
– 1-10, 14, 17, 18, 20, 23, 24, 28
 Page 795 1-10
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