What are disadvantages of radial symmetry?

Answer 1

The main disadvantage to radial symmetry (eyes on the side of the head as opposed to the front) is that vision is mostly two dimensional. A creature with eyes on the sides of its head can only focus both its eyes on an object if the object is directly in front of it. This makes the range (distance) and comparative size of other creatures and objects harder to judge. It also makes discerning camoflaged creatures from their surroundings much more difficult. For raptors (Birds of Prey), radial symmetry presents a lot of problems when hunting. These are overcome by various other natural systems such as improved spatial awareness and superlative hearing.

Answer 2

Bilateral symmetry means that the sensory organs are grouped around the head of an organism. In this case, the organism may not be able to see behind it or smell. In bilateral symmetry, the sensory organs are not evenly distributed throughout the body.