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

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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