Phylum Annelida | Definition, Characteristics, Classification, Examples

Definition Annelids are cylindrical, triploblastic, coelomate animals with metameric segmentation. They have a peculiar nephridial system and a well-developed organ grade of organization. They inhabit terrestrial as well as aquatic marine habitat. Some 7000 species are known at present. Brief History They were first classified along with other unsegmented worms in phylum Vermes by Linnaeus … Read more

Phylum Nematoda (Nemathelminthes)- Definition, Classification, Characteristics, Examples

Nematodes are unsegmented vermiform animals that are commonly known as “Roundworms” Introduction This phylum includes roundworms and threadworms (Gr. Nema = thread, cidos = form), which are cylindrical, triploblastic, bilaterally symmetrical animals with organ grade of organization, with all organ systems developed except circulatory, respiratory and locomotory organs. A false body cavity of pseudocoel is … Read more

Phylum Platyhelminthes- Definition, Characteristics, Classification, Examples

Definition Phylum Platyhelminthes includes Animals with organ grade of organisation and first to have triploblastic organisation. They do not have coelome, and are dorsoventrally flattened and life cares with flame cells. Some 10,000 species are known by now. A Brief History The tapeworms and other flat worms were known from ancient times. Linnaeus (1735) included … Read more

Phylum Coelenterata (Cnidaria) | Definition, Classification, Characteristics and Examples

Phylum Coelenterata is a group of aquatic or marine organism that comes under Animal Kingdom. These are also known as Cnidaria. (G.k. Kilos-hollow, enteron-intestine) General Characteristics of Coelenterata Fresh water and marine in habitat. Solitary or colonial in nature. Body is radially symmetrical. Body wall is diploblastic (i.e., Outer ectoderm and inner endoderm). Presence of … Read more

Phylum-Porifera | Definition, Characteristics, Classification, Examples

Porifera are multicellular organisms with a cellular grade of organization. They are devoid of tissues. Porifera means (Gr. Porus = pore, fere = to bear) pore bearing. The body wall of sponges is beset with many Ostia, i.e., pores. Water current enters through these pores and goes out via the osculum, an opening at the … Read more

Kingdom Animalia- Characteristics, Classification, Examples

Kingdom Animalia comprises all the animals present. Animals are also known as Metazoa are multicellular eukaryotic organisms that come under the biological kingdom Animalia. Animals are arranged under major groups, known as phyla. There are 10 major phyla (as shown in the figure below) that have been taken into consideration at the elementary level of … Read more