This group involves all the living as well as extinct living speciesAs there are millions of species available, the classification of them is very importantBesides, it helps in assigning a systematic position to newly discovered speciesIn spite of differences in form and structure of various animals’ species, there are elemental features common to various individuals in relation to the arrangement of cells, nature of coelom, body symmetry, circulatory, patterns of digestive, or reproductive systems.
Animals can be categorised into two types on the basis of their symmetry.
Radial symmetry: In this category the body divides the organism into two identical halves when any plane passing through the central axis
Bilateral symmetry: In this category where the body can be divided into identical left and right halves in only one planeAnimals such as arthropods, annelids demonstrate bilateral symmetry.
Animalia can be broadly classified into two types
- Cellular level: Porifera
- Tissue/Organ/ Organ system
Tissue/Organ/ Organ system can be classified into two types
- Radial
- Bilateral
Bilateral can be classified into three types
- Without body cavity (acoelomates)
- With false coelom (pseudocoelomates)
- With true coelom (coelomates)
With true coelom (coelomates) can be further classified as
- Annelida
- Arthropoda
- Mollusca
- Echinodermata
- Hemichordata
- Chordata
Here are some important points of Phylum
Phylum- Porifera: The organisms of this phylum are generally known as spongesThey are usually marine and typically asymmetrical animalsThey show cellular level of organisation and are primitive multicellular animals.
Phylum – Coelenterata (Cnidaria): They are radially symmetrical animalsBasically, they are aquatic (mostly marine), sessile or free-swimming animalsThe name cnidaria is derived from the cnidocytes or cnidoblastsCnidoblasts are utilized for defense, anchorage, and for the capture of preyCnidarians are diploblastic and demonstrate tissue level of organisation.
Phylum – Ctenophora: Ctenophores are radially symmetrical which are commonly known as comb jellies or sea walnutsThey are exclusively marine, diploblastic organisms with tissue level of organisation.
Table of Contents
Phylum – Platyhelminthes
They are commonly called as flatworms as they have dorso-ventrally flattened bodyThese are mostly endoparasites found in animals including human beingsFlatworms are triploblastic, bilaterally symmetrical, and acoelomate animals with organ level of organisationSuckers and hooks are present in the parasitic formsSome of them extract nutrients from the host via their body surface.
Phylum – Aschelminthes
They are known as roundworms as the body of the aschelminthes is circular in cross-sectionThey may be freeliving, terrestrial and aquatic or animals and parasitic in plantsThe body organisation Roundworms is of organ-system levelThey are triploblastic bilaterally symmetrical, and pseudocoelomate animals.
Phylum – Annelida
They may be terrestrial or aquatic (fresh water and marine); free-living, and sometimes parasiticThe body organisation is of organ-system level and bilateral symmetryThey are metamerically segmented, triploblastic, and coelomate animals.
Phylum – Arthropoda
Arthropoda is the largest phylum of AnimaliaInsects are belonging to this phylumOver two-thirds of all named species on earth are arthropodsThey exhibit organ-system level of organisation and bilaterally symmetricalThey are segmented, triploblastic, and coelomate animalsChitinous exoskeleton cover the body of arthropodsThe body consists of head, abdomen, and thoraxThey have jointed appendages (poda-appendages, arthros-joint)They have respiratory organs are book gills, gills, tracheal system or book lungs.
Phylum – Mollusca
Mollusca is the second largest animal phylum after arthropodaMolluscs are aquatic (marine or fresh water) or terrestrial animalsThey exhibit an organ-system level of organisationThey are triploblastic, bilaterally symmetrical, and coelomate animalsCalcareous shell usually covers their bodyThey are unsegmented with muscular foot, a distinct head, and visceral humpA spongy and soft layer of skin forms a mantle over the visceral hump.
Phylum – Echinodermata
They are known as Echinodermata as these animals have an endoskeleton of calcareous ossiclesThe animal belonging to this group are marine with organ-system level of organisationThe larvae of this phylum are bilaterally symmetrical but adult echinoderms are radially symmetricalThey are coelomate and triploblastic animals.
Phylum – Hemichordata
This phylum includes a small group of worm-like marine animals which are usually organ-system level of organisationIn general, they are triploblastic, bilaterally symmetrical, and coelomate animals.
Phylum – Chordata
Animals of the phylum Chordata are basically characterisedthe presence of a a dorsal hollow nerve cord, notochord, and paired pharyngeal gill slits.
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