Question

Explain the distinguishing features of Animalia.

Answer 1

All animals belong to Kingdom Animalia are multicellular. They don't have a reserve cell wall like plant cells and the body is made up of cells which are organized into tissue. They mainly reproduce sexually by means of differentiated eggs and sperms.

Complete answer:
All animals belong to Kingdom Animalia are eukaryotes and they are heterotrophic which means they get their nutrition from organic sources.
Some of the distinguishing features of kingdom Animalia are-

1. Kingdom Animalia has two levels of organization i.e cellular level and tissue/organ/organ system level.
   On the cellular level Animalia include the phylum Porifera.
   2)Tissue/organ/organ system level includes two types of symmetry radial symmetry and bilateral symmetry. phylum Coelenterata and Ctenophore have radial symmetry.
   3)Animals having bilateral symmetry are again divided on the basis of their body cavity or coelom.
   Without body cavity - phylum Platyhelminthes
   With false coelom - phylum Aschelminthes
   With true coelom - phylum Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata.
   -Animal Kingdom characterized on the basis of their symmetry. Sponges are asymmetrical, echinoderms, Coelenterates, Ctenophores have radial symmetry. Animals like Arthropoda, annelids have bilateral symmetry.
   -Animals are also characterized on the basis of the diploblastic and triploblastic organization. In diploblastic animals, cells are arranged in two embryonic layers i.e external endoderm and an internal endoderm. In triploblastic animals, the developing embryo has a third germinal layer (mesoderm).
   -Animals are also classified on the basis of their segmentation.
   -Animals are classified on the basis of the notochord present in them.chordates are the animals with a notochord and non-chordates are the animal without notochord.

Note: In spite of differences in their structures and form, all animals constitute features common to various individuals which are related to their symmetry, arrangement of cells, their digestive, circulatory or reproductive systems, and nature of coelom.