Chordates (Chordata) Our phylum

Chordates have a backbone 1. Dorsal hallow nerve cord 2. _________________: strong rod that separates digestive and nerve cord 3. Pharyngeal slits: ______________________________________________ 4. Post anal tail (behind the anus) Invertebrate chordates: (no backbone but do have major hallmarks of chordates!) – _______________ (only have these structures in their larval stages) – ___________________: (another invertebrate chordate, have segmented muscle structure)

Fish to JAWS (literally) Fish started without jaws – Agnathans/Lampreys are a group of vertebrates that ________ ___________________________. Mud suckers and suspension feeders The Jaw allowed for a variety of prey – Chondrichthyes: _______________ _____________ (sharks, rays and skates) Use a ____________________ to detect changes in water pressure and nearby swimming creatures (predators or prey)

More on fish evolution Another kind of fish with a jaw is the ______________ (boney fish) – Have an operculum which allows for gas exchange even when they aren’t moving – Contain a ________________ which keeps them buoyant (lung like structures that fill with air but don’t exchange gases)

Amphibians lead a double life Dependent on water for their eggs to develop Larva swim in water _______________________________ _______________________________ _______________________________ ____________ After metamorphosis the adolescent crawls onto land Largest population during the Carboniferous period before reptiles or mammals ** Currently undergoing a rapid decline due to acid rain (high amount so carbon dioxide in the air)

Reptiles Amniotic egg: like the seed, ___________________________ ___________________________ ____________ Scales that protect their bodies from water loss _____________________: don’t use metabolism to regulate body temp. (cold blooded) Some dinosaurs may have been endothermic (using metabolism for body temp.) Include – Lizards – Snakes (lost legs secondarily) – Turtles – Crocodiles – Alligators

How a reptile became a bird Derived from a group of small 2 legged dinosaurs __________________________ __________________________ _____________(Archaeopteryx) Archaeopteryx is not an ancestor but it give us info about what they would be like – Scales on feet, vertebral tail, scales on claws, feathers on arms, webbed fingers – Many birds died with the dinosaurs, those that survived went on to be modern birds

More on Birds Every aspect of birds has been evolved for flight… they “trimmed the fat” – Hallow feathers – ___________________ – No teeth – ___________________ Different styles of wings are excellent at different things, some are for soaring, some for quick maneuverability, Some to be able to stay still. – Some rare birds of course don’t fly (like the ostrich!) Endothermic!!! 4 chambered heart (___________________________)

Mammals come from reptiles too! Mammals diverged from reptiles long before even dinosaurs evolved! Independent 4 chambered heart Lived a meager existence until the fall of the dinosaurs opened up the availability for them to survive. ________________________________ ________________________________ ________________ ______________________… have a placenta which bridges the gap between mother and child Marsupials are a kind of mammal that has a very short gestation then carries the young nursing them after they are born until they are able to live on their own.

Phylogeny of animals summary