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Chapter4 Lessons1-4


homeostasis The condition in which an organism's internal environment is kept stable in spite of changes in the external environment .
adaptation An inherited behavior or physical characteristic that helps an organism survive and reproduce in its environment.
vertebrate An animal WITH a backbone.
invertebrate An animal WITHOUT a backbone.
tissue A group of similar cells that perform a specific function.
organ A body structure that is composed of different kinds of tissues that work together .
radial symmetry A body plan in which any number of imaginary lines that all pass through a central point divide the animal into two mirror images.
bilateral symmetry A body plan in which a single imaginary line divides the body into left and right sides that are mirror images of each other.
cnidarian A radially symmetrical invertebrate that uses stinging cells to capture food and defend itself.
mollusk An invertebrate with a soft, unsegmented body; most are protected by a hard outer shell.
arthropod An invertebrate that has an external skeleton, a segmented body, and jointed appendages.
exoskeleton External skeleton; a tough, waterproof outer covering that protects, supports, and helps prevent evaporation of water from the body of many invertebrates.
echinoderm A radially symmetrical marine invertebrate that has an internal skeleton and a system of fluid-filled tubes.
endoskeleton An internal skeleton; structural support system within the body of an animal.
chordate An animal that has a notochord, a nerve cord and throat pouches at some point in its life.
notochord A flexible rod that supports a chordate's back just below the nerve chord.
vertebra A stack of many small bones called vertebrae. A single one of these bones is a vertebra.
ectotherm An animal whose body temperature is determined by the temperature of its environment.
endotherm An animal whose body temperature is regulated by the internal heat the animal produces.
Created by: IsabellaDay