Understanding the Phylum Chordata: Evolution and Characteristics of Vertebrates and Ectotherms
Chapter 3 explores the Phylum Chordata, emphasizing key features such as the notochord, hollow nerve cord, pharyngeal pouches, and tail present during various life stages. It classifies chordates into three groups: Lancelets, Tunicates, and Vertebrates—the latter being the largest group characterized by having a backbone. The chapter delves into different vertebrate classes, including Fish, Amphibians, and Reptiles, detailing their evolutionary history, physiological traits, and adaptations. It also examines ectothermic and endothermic classifications among chordates.
Understanding the Phylum Chordata: Evolution and Characteristics of Vertebrates and Ectotherms
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Presentation Transcript
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 toads Bumpy skin Dry skin Lay eggs in strings • Smooth skin • Moist skin • Lay eggs in bunches
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
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
