BIOL 1002 Study Guide - Midterm Guide: Nematode, Annelid, Mollusca
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In addition to these characteristics, as animals evolved, they developed more complex and organized bodies. Some of these increases in complexity and organization are: Cephalization is the concentration of nervous tissue (including a brain and sensory organs) into a defined region (head) of the body. Segmentation is a body design in which similar repeating units are present. (ex. These and other characteristics are used to define the phyla of animals. Table 23. 1 (phyla: porifera, cnidaria, playyhelminthes, annelida, mollusca, anthropoda, Cellular specialization leads to the development of tissues, which then can lead to the combination of tissues into an organ. Organs may then become arranged into organ systems. Tissues are specialized cells with a common structure and function that are grouped together. Organs are centers of bodily function, which are usually made up of different tissues. Organ systems are groups of two or more organs that function together to perform a common task (e. g. , digestion, gas exchange, reproduction.
