Biology Principles and Explorations Chapter 28

hollow ball of cells that gives rise to all the tissues and organs of an adult body

in animals, the outer layer of embryonic tissue from which the skin and nervous system develop

inner layer of embryonic tissue from which the digestive organs develop in animals

middle layer of embryonic tissue in animals from which the skeleton and muscles develop

An animal's shape, symmetry, and internal organization

irregular in shape

arrangement of body parts around a central axis

arrangement of body parts so there are distinct left and right halves that mirror each other

in bilaterally symmetric animals, the development of a head end with a concentration of nerves and sensory structures

fluid-filled body cavity that forms between the body wall and the digestive tract

an animal that lacks a coelom, or body cavity

animal with a body cavity located between the endoderm and the mesoderm

animal with a body cavity located entirely within the mesoderm

branching diagram that shows how animals are related through evolution

a digestive cavity with only one opening; found in simple animals

simultaneous uptake of oxygen and release of carbon dioxide, by the lungs, gills, or through the skin

extremely thin projection of tissue rich in blood vessels that in the site of gas exchange in aquatic and a few terrestrial animals

system in which blood leaves the blood vessels and bathes the body's tissues

system in which the blood does not leave the blood vessels and materials diffuse across the walls of the vessels

support structure that consists of water contained under pressure in a closed cavity

hard external covering of some invertebrates

an internal skeleton composed of a hard material, such as bone

an organism that contains both the male and female reproductive organs (testes and ovaries)

union of egg and sperm occuring outside the body of either parent

fertilization that occurs within the body of the female parent