Radial symmetry is not found in: 

• Radial symmetry refers to the arrangement of parts of organisms around a single axis that can be divided into equal halves across any plane. 
• This type of symmetry is seen in some sessile aquatic animals. 
• Animals of the phyla Cnidaria (Hydra) and Echinodermata (starfish) show radial type of symmetry. 
• Spider belongs to phylum Arthropoda which shows bilateral symmetry. 
• Thus, the correct answer is option C.