Question

Almost all animals except _____ have either radial or bilateral symmetry

Answer 1

Ans.

Symmetry in animals can be defined as the balanced distribution of identical body shapes or parts within an organism's body. All animals, except sponges have either radical or asymmetry.

Sponges belong to phylum Porifera, which exhibit asymmetrical body plans. Their body shapes are adapted for maximum efficiency of water flow through their central cavity.

Thus, the correct word to be filled in the blank is 'sponges.'

Answer 2

Sponges are the only animals which have asymmetrical body. Asymmetrical animals are animals which do not have pattern of symmetry. Sponges is an aggregation of different sponge cells. They form a colony with different shapes.