Phylum Chordata

Phylum Chordata All members of Phylum Chordata: Have a dorsal nerve cord that becomes the basis for spinal cord/nervous system Have a notochord at some point in development (a skeletal rod that runs under dorsal nerve) Have a tail at some point in development Have a muscular tube called a pharynx (used in feeding or respiration). Gill slits some point in development

Vertebrata Many members of Phylum Chordata have bony structures to surround and protect the dorsal nerve (they are vertebrates) 95% of Phylum Chordata are vertebrates Can be ectotherms (body temperature regulated by outside environment – fish, reptiles, amphibians) or endotherms (regulate own body temperature – birds and mammals) Classes of Vertebrates with living members:

Class Agnatha Jawless fish Long, tube-like, slimy bodies Lack paired fins Skeleton made of cartilage Mouth is suction-like with sharp teeth. They clamp onto prey and suck out blood and bodily fluids. Ex. Lamprey, hagfish https://www.youtube.com/watch?v=NYRr_MrjebA

Class Chondrichthyes Skeleton made of cartilage Paired gills for breathing underwater (gills filter oxygen from water) Fins for swimming Can have whip-like tails and potentially stingers Moveable jaws with developed teeth Some lay eggs, some give birth to live young Ex. Sharks, skates, stingrays

Class Osteichthyes Bony fish Bone skeleton Gills for breathing Paired fins Thin, flexible scales Have a gas-filled structure called a swim bladder, which allows for swimming at different depths. Offspring produced via eggs laid by the female Ex. Fish.

Class Amphibia Have two life stages: Reproduction occurs in water. Eggs hatch here and tadpoles grow here. Breath through gills. As adults, they move onto land and breath through lungs. As adults, live near water, must keep skin moist. Can exchange gases through skin. Carnivores: eat insects Ex: Frogs, toads https://www.youtube.com/watch?v=SgROaJY6Xnk

Class Reptilia Terrestrial, although some spend time in water. Have lungs Thick scales that are water-proof and help prevent water loss Lay amniotic eggs – eggs that provide a moist, self-contained environment for the embryo. Have leathery or calcium shells Can ‘walk’ via limbs (unless you’re a snake), which have knee joints – allows for greater range of motion Ex. Snakes, crocodiles, turtles

Class Aves Evolved from reptiles Have feathers to provide insulation and protection (evolved from scales) Wings for flight Skeleton is very light weight – bones hollow Beak-like structures Very high metabolisms to allow for flight and to maintain temperature Ex. All birds, including flightless ones like penguins and ostrich https://www.youtube.com/watch?v=AVaITA7eBZE

Class Mammalia Young are carried within the body and born alive (i.e. not laid in eggs) Have fur/hair Terrestrial, with lungs to breathe air Females produce milk via mammary glands to feed young Teeth replaced only once in life (milk teeth  adult teeth) Four chambered heart Lower jaw is a single bone