GENERAL KNOWLEDGE

Detailed explanation-1: -Five-part radial symmetry. All echinoderms are bilaterally sym-metrical as larvae. During their development into adults, the larvae’s body plan becomes radially symmetrical. Most adult echinoderms, such as the one shown on the left in Figure 4, have a five-part body plan with arms that radiate from a central point.

Detailed explanation-2: -Although they may appear very different, echinoderms all have two major defining characteristics that set them apart from all other animals: a water vascular system and five-sided radial symmetry.

Detailed explanation-3: -In a typical sea star, it is easy to see the classic five-fold symmetry that is characteristic of echinoderms. This includes arms projecting outwards around a centralized axis. Even sea cucumbers, which show a more worm-like appearance, usually exhibit this body plan, known as pentameral symmetry.

Detailed explanation-4: -Explain how all echinoderms show five-sided radial symmetry when they look so different. Echinoderms have a radial symmetry, which means that the body is divided into five equal parts, or rings. This symmetry is seen in the way they look different from other animals, since they have five-sided shapes.