Mouth, pharynx, esophagus
<span>The reaction required an input of energy.</span>
Directional selection acts against b<span>oth extremes simultaneously in the variation of the trait. This is the most "aggressive" form of selection and only happens in extreme areas.
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Segmented digestive system, appendages are animal characteristics.
Animals are a major group of organisms, classified as the kingdom Animalia or metozoa. Animals have several characteristics that set them apart from other living things. They are all eukaryotic and usually multicellular, which separates them from bacteria and most protists. Different animals differ in their own characteristics such as appendages, segmentation among other animal characteristics.
