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body parts arranged in a similar way on both sides of the body, with each half being nearly a mirror image of the other half
thick, hard, outer covering that protects and supports arthropod bodies and provides places for muscles to attached
animal that has a notochord, a nerve cord, pharyngeal pouches and a postanal tail present at some stage of development
tubelike structure above the notochord that in most chordates develops into the brain and spinal cord
supportive framework of bone and/or cartilage that provides an internal place for muscle attachment and protects a vertebrate's internal organs
tough, flexible tissue that joins vertebrae and makes up all or part of the vertebrate endoskeleton
backbones that are joined by flexible cartilage and protect a vertebrate's spinal nerve cord
vertebrate animal whose internal temperature changes when the temperature of its environment changes
inactivity in cold weather; cyclic response of inactivity and slowed metabolism that occurs during periods of cold temperatures and limited food supplies
egg covered with a shell that provides a complete environment for the embryo's development; for reptiles, a major adaptation for living on land
strong, lightweight feather that give birds their coloring and shape and that are used for flight
soft, fluffy feathers that provide an insulating layer next to the skin of adult birds and that cover the bodies of young birds
endothermic vertebrates that have hair, teeth specialized for eating certain foods, and mammary gland, in females, mammary glands produce milk for feeding their young
a mammal that lays eggs with tough, leathery shell and whose mammary glands do not have nipples
period during which an embryo develops in the uterus, the length of times varies among species
an organ that develops from tissues of the embryo and tissues that line the inside of the uterus and that absorbs oxygen and food from the mother's blood
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