Lesson 1: Introduction to Worms
Bilateral Symmetry
Like humans, these worms have bilateral symmetry. This means that there is only one way in which you could divide the organism and get mirror images. Bilateral organisms have an anterior, or front, and a posterior, or rear end. Sensory organs such as eye spots and the center of any nervous system will be located in the anterior end.
Additionally, bilaterally symmetrical organisms have a back or dorsal surface that is different from the belly or ventral surface. Bilateral symmetry allows animals to be more active in the pursuit of prey and to have more sophisticated behaviors.
Photo Attribution
Description: Bilateral Symmetry
Source: http://www.baileybio.com/plogger/?level=picture&id=1474 (Fair Use: August 15, 2012)