EVERYDAY SCIENCE

Detailed explanation-1: -The body plan of cnidarians is unique because these organisms show radial symmetry, making these animals very different from those that evolved before them. Radial symmetry means that they have a circular body plan, and any cut through the center of the animal leaves two equal halves.

Detailed explanation-2: -The body plans cnidarians generally have radial symmetry (Fig. 3.25 A). Because the tentacles of corals, jellyfish, and sea anemones have this radial structure, they can sting and capture food coming from any direction.

Detailed explanation-3: -Cnidarians have radial symmetry. Echinoderms are bilateral animals that have a 5-part radial symmetry as adults.

Detailed explanation-4: -Cnidarians are radially or biradially symmetric, a general type of symmetry believed primitive for eumetazoans. They have achieved the tissue level of organization, in which some similar cells are associated into groups or aggregations called tissues, but true organs do not occur.