chapter 3. phylum chordata at some point of their lives, all have a: - notochord - hollow nerve cord...
TRANSCRIPT
Chapter 3
Phylum Chordata
At some point of their lives, all have a:- notochord
- hollow nerve cord- pharyngeal pouches- tail
Three groups of Chordates
• Lancelets• Tunicates • Vertebrates – largest group – has a backbone
No backbone
Vertebrates
• Backbone or vertebral column - Protects spine
- Support• Endoskeleton
-Support -Shape -grows with the organism
Groups of Chordates
• Eight Groups- Six are ectotherms
-Rely on environment for heat - “cold blooded”
- Two are endotherms - Maintain their body heat - “warm blooded”
FISH• Evolved 540 mya• Ectotherms• Water dwelling vertebrates• Scales (most)• Fins• Gills• Most do external fertilization
Jawless Fish• Most primitive• No scales, fins, bones or
jaw• Has skeleton made of
cartilage• Examples- hagfish and
lamprey
Cartilaginous Fish• Skeleton made of
cartilage• Tooth-like scales• No swim bladder• Sharks, skates, and
rays
Bony Fish
• Have a swim bladder -Gives the ability to float or sink• Color vision• Lateral line that senses movement
AMPHIBIANS• Evolved 350 mya• Ectotherms• Lungs• Breathe through skin• Term amphibian means “double life”• Live on land and water – soft eggs• Goes through metamorphosis• Ecological indicators
Caecilians• Legless amphibian• Lives in damp soil in
the tropics• Eats small
invertebrates• Thin moist skin• Small eyes under skin
but are blind
Salamander
• 390 known species• Eats small vertebrates• Long tail and four
small legs
How Frogs and Toads are Alike • 90% of all amphibians are frogs and toads• Found all over the world• Highly adapted for life on land• Sticky tongues that are attached to the front of
the mouth instead of the back• Strong legs for jumping• Ears• Vocal cords
How Frogs and Toads are Different
frogs• Smooth skin• Moist skin• Lay eggs in bunches
toads• Bumpy skin• Dry skin• Lay eggs in strings
Frog Life Cycle
REPTILES• Thick, dry, water tight skin• Ectotherms• Lungs to breathe• Evolved 300 mya • Strong vertical legs • Most lay thick rubbery eggs. This allows them
to reproduce on land• Internal fertilization
Reptile eggs
• Shell - protects the egg• Albumen – provides water and protein• Amniotic sac - protects embryo• Yolk - provides food• Allantois – stores waste and passes oxygen
ter
Lizards • About 4,000 species• Live in deserts, jungle, forests and grasslands• Most eat small invertebrates and plants but
some are strictly herbivores• The tail of some lizards separate from the
body when the lizard is grabbed. The tail that is left behind wriggles, confusing the other animal.
Turtles and Tortoises
• 250 species• Slow and inflexible• Protective shell• Tortoises live on land and have bumpy shell• Turtles live on land and have smooth shells
Snakes
• About 1600 species• No legs• Scales on belly pull snake
forward• Carnivores with a good
sense of smell
Alligators and Crocodiles
• Eyes and nose on top of head so they can hide under water
• Alligators have a rounded snout, crocodiles have a narrow snout
Alligators and Crocodiles