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members of the chrodate phylum who have a notochord, a nerve chord, and slits in their throat area at some time in their lives


a flexible rod that supports the animal's back


a connective tissue that is softer than bone, but flexible and strong


many similar disc-shaped bones that form the backbone


an animal whose body does not produce much internal heat


an animal whose body controls and regulates its temperature by controlling the internal heat it produces


a vertebrate that lives in water and has fins

swim bladder

and internal gas-filled sac that helps the fish stabilize its body at different depths

buoyant force

the force that water exerts upward on any underwater object


an ectothermic vertebrate that spends its early life in water


two upper chambers of the heart


two lower chambers of the heart which pump blood out to the to the lungs and body


a specific environment in which an animal lives


an ectotherminc vertebrate that has lungs and scaly skin


a watery fluid that wastes are excreted in


the hardened remains or other evidence of a living thing that existed a long time in the past

sedimentary rock

the type of rock made of hardened layers of sediments--clay, sand, mud, or silt


the scientists who study extinct organisms

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