Page 1 - 2.Lesson Notes-Animalia 1

SAI International School
Subject- Biology, Class-IX
Chapter- Diversity in living organisms
Sub Topic- Animalia: Porifera, Coelenterata, Platyhelminthes,
Nematoda
Module- 27
Lesson Notes

Kingdom Animalia--------

• Kingdom Animalia is made up of eukaryotic, multicellular, heterotrophic
organisms.
• Mode of nutrition is holozoic and they are either herbivores or carnivores.
• Most animals are motile, they can move independently in search of food,
shelter or mate.
• Animals are made up of many organ systems, that aids in performing specific
functions that are necessary for the survival of the organism.
Most of the animals are bilaterally symmetrical, while primitive animals are
asymmetrical and cnidarians and echinoderms are radially symmetrical.

Basis of classification--------

Important terms-----------

Radial symmetry: A symmetry where any plane passing through the central axis
divides the body into two equal halves is called the radial symmetry. Examples are
Coelenterates, ctenophores and echinoderms.

Bilateral symmetry: In bilateral symmetry, only a single plane divides the body into
two equal halves, e.g. annelids, arthropods, molluscs, etc.